Nouvelle Série, Tome XI, Fasc. 3-4

1976

REVUE

ALGOLOGIQUE

Fondée en 1922 par P. ALLORGE et G. HAMEL

Directeurs : P. BOURRELLY et R. LAMI

Secrétariat de Rédaction : M. RICARD

SOMMAIRE

P. BOURRELLY. - Einar TEILING (1888-1974). 205

Y. LE CALVEZ. - Georges DEFLANDRE (1897-1973). 209

U. GERSON. - The associations of Algae with Arthropods (2nd part,

Addendum).213

J. P. CULLINANE. - Vaucheria on «Coral» ( Lithothamnion ) Sand.249

E. FJERDINGSTAD, Bo HOLMA and E. J. FJERDINGSTAD. - The

structure of Oscillatoria limosa Ag. (Cyanophycea) and the formation

of hormogonia and necridia.261

A. COÛTÉ. — Étude comparative du cycle de Liagora tetrasporifera Bôrg.

et du Liagora distenta (Mert.) C. Ag. en culture.273

H. M. PARKES. — The presence of tetrasporangia and carposporophytes

on the same thallus in Pterosiphonia thuyoides .299

D. M. JOHN. — The marine algae of Ivory Coast and Cape Palmas in Libe¬

ria (Gulf of Guinea).303

R. T. TSUDA. — Some marine benthic algae from Pitcairn island.325

M. KHAN and A. MATHUR. — Algal flora of the rice-fields around Dehra-

dun, India.333

P. COMPERE. — Bourrellyodesmus, nouveau genre de Desmidiacées.339

M. RICARD. - Premier inventaire des diatomées marines du lagon de

Tiahura (île de Moorea, Polynésie Française).343

P. BOURRELLY. - ANALYSES BIBLIOGRAPHIQUES.357

205

EINAR TEILING (1888-1974) *

P. BOURRELLY

Le 21 août 1974, Einar TEILING, le doyen des algologues d’eau douce, s’est

éteint doucement à Lund, à l’âge de 86 ans.

Il était né le 21 mars 1888 à Stockholm où il prépara à l’Université, de 1907

1917, la licence de Sciences Naturelles. A cette époque, tout en continuant

es études, il enseignait à l’école Beskow de 1908 à 1919; il acheta alors son

Je remercie très vivement mon ami, le Dr. K. THOMASSON, de l’Université d’Uppsala, de

l’avoir fourni les documents nécessaires à la rédaction de cette notice (voir THOMASSON,

975, Sv. Bot. Tidskr. 69 : 191-197.

Rev. Algol, N. S., 1976, XI, 3-4 : 205-208.

Source : MNHN, Paris

206

P. BOURRELLY

premier microscope et s’intéressa vivement à la géologie et à l’algologie des

eaux douces. Il fut, à l’Université, l’élève du Prof. G. LAGERHEIM.

Son intérêt passionné pour les algues le mit en relation avec le grand desmidio-

logue O. BORGE. Celui-ci lui ouvrit largement sa riche bibliothèque et sa col¬

lection de dessins algologiques. Le jeune TEILING, qui était excellent dessina¬

teur, comprit l’importance capitale de la documentation et commença alors à

se constituer une iconothèque et une bibliothèque spécialisée.

Ces collections ont été léguées à la section algologique de l’Université d’Up-

psala. Le Dr. TEILING était avant tout un homme de «terrain» et ses vacances

se passaient à récolter des algues planctoniques des innombrables lacs suédois.

Dès 1912 il put ainsi publier sa première note sur le Phytoplancton d’un lac

proche de Stockholm. En 1916, une nouvelle note suivra où il décrira le nou¬

veau genre de Chlorococcale : Tetrallantos.

Au début de la première guerre mondiale il travaille pendant un mois dans le

laboratoire du Prof. KOLKWITZ à Berlin et se familiarise ainsi avec la notion

des algues indicatrices de pollution.

En 1916 il publia, sur les conseils de WESENBERG qu’il a visité en 1913,

une étude sur la formation phytoplanctonique qu’il appelle «calédonienne»

(comparable à celle trouvée par W. et G. S. WEST en Ecosse) et l’oppose à

une formation «baltique». Ces formations, floristiquement très différentes, se

retrouvent dans des lacs voisins mais se distinguent par leur âge géologique, leur

sous-sol, et leur environnement. Ce travail, écrit en suédois, resta malheureuse¬

ment inconnu hors de Suède. Cela est fort regrettable, car il contenait en germe

la distinction fondamentale entre plancton d’eau pauvre en éléments nutritifs

(calédonien) et plancton d’eau riche en substances dissoutes (baltique). C’est ce

que NAUMANN en 1919, appellera milieu oligotrophe et milieu eutrophe.

TEILING, cependant, insistait davantage non sur la productivité mais sur

l’aspect qualitatif du phytoplancton.

Sa licence terminée TEILING est nommé professeur à l’École Normale de

Stràngnâs (1919-1931) puis à Vâxsjô (1931-1937) et enfin à Linkôping (1937-

1953). Il va ainsi pendant 25 années se consacrer uniquement à l’enseignement.

Mais en 1940, le Prof. G. E. DU RIETZ, ayant retrouvé Tetrallantos dans un lac

voisin d Uppsala, entre en relation avec le Dr. TEILING, lui demande confirma¬

tion de ses déterminations d’algues et l’encourage à reprendre ses travaux de re¬

cherches. TEILING étudie alors avec soin le phytoplancton de plus de 600 lacs

suédois et publiera jusqu’en 1967 une série de notes et de mémoires qui font

autorité. Il se penche particulièrement sur la morphologie des chloroplastes des

Desmidiées, et montre son importance tant pour la taxinomie que pour la phylo¬

génie. Il arrive ainsi par des voies différentes à des conclusions voisines de celles

de CHADEFAUD sur l’évolution des plastes.

Ses études sur le polymorphisme de ces algues lui permettent de ressusciter

le genre Actinotaenium et de créer le nouveau genre Staurodesmus. Ce dernier

taxon groupe, en une synthèse intelligente, des formes bipolaires et multipo-

EINAR TEILING

207

laires que la systématique classique séparait sous des noms de genres différents

tels que Staurastrum et Arthrodesmus. Ce genre Staurodesmus créé par TEI¬

LING en 1948 a fait l’objet en 1967 d’une monographie qui restera comme un

modèle de clarté et de logique.

La grande activité scientifique de E. TEILING est enfin reconnue officielle¬

ment et de 1945 à 1958 il est chargé de cours d’écologie et de taxinomie du

phytoplancton à l’Institut Limnologique de l’Université de Lund et au Labora¬

toire d’Aneboda. Enfin en 1950, il reçoit la distinction suprême de Docteur

honoris causa de l’Université de Lund.

En 1960, il s’installe à Lund mais garde des liens étroits avec l’Université

d’Uppsala. Malgré son âge avancé, il demeure le conseiller des jeunes algologues

(et même des «moins jeunes») et sa bibliothèque et sa vaste érudition sont à la

disposition de tous les chercheurs.

Il ne faudrait pas croire que l’enseignement et l’algologie suffisaient à remplir

la vie de E. TEILING. Il adhérait à de nombreuses sociétés savantes et fut le

doyen des membres de la société botanique suédoise. De plus, grand amateur de

musique, il avait participé à la fondation de la Société de Musique de Stockholm;

il était aussi membre d’un club automobile et d’une société de photographie

dont il était le fondateur.

Ce grand algologue dont nous venons de retracer brièvement la vie nous laisse

• e souvenir d’un esprit curieux, amateur et observateur passionné de la nature et

de ses secrets, et en même temps ouvert aux côtés humains de l’existence.

Ainsi tous ceux qui l’ont approché ont apprécié sa grande culture, sa bonté

ouriante, sa simplicité, son esprit plein d’humour et d’indulgence.

Je le connaissais personnellement depuis 25 ans et ses conseils et son amitié

îe m’ont jamais fait défaut. Je me souviens toujours avec émotion du jour de ma

outenance de thèse où je reçus de Suède, avec une lettre de félicitation, une

gerbe de fleurs de sa part. Ce geste montre toute la délicatesse de son amitié.

L’algologie a perdu avec le Dr. TEILING, un de ses maîtres, et moi un ami

rès cher.

PUBLICATIONS PHYCOLOGIQUES D’EINAR TEILING

■ 909 — En fossilfôrande postglacial ôstersjôlera. Geol Fôren. Fôrh. 31 : 52-64.

1912 — Phytoplankton aus dem Rastasjôn bei Stockholm. Svensk bot. Tidskr. 6 : 266-281.

L916 — Schwedische Planktonalgen. 2. Tetrallantos, ein neue Gattung der Protococcalen.

Svensk. bot. Tidskr. 10 : 59-66.

208

P. BOURRELLY

1916 — En kaledonisk fytoplanktonformation. Svensk. bot. Tidskr. 10 : 506-519.

1941 — Aeruginosa oder flos-aquae. Eine kleine Microcystis Studie. Svensk bot. Tidskr.

35 :337-349.

1942 — Schwedische Planktonalgen. 3. Neue oder wenig bekannte Formen. Bot. Notiser :

63-68.

1942 — Schwedische Planktonalgen. 4. Phytoplankton aus Roslagen. Bot. Notiser : 207-217.

1944 — Vara viktigare fytoplankter. Biol, larar. Fôren. Medlemsbl. : 15-24, 39-43, 46-58.

1946 — Zur Phytoplanktonflora Schwedens. Bot. Notiser : 61-88.

1947 — Staurastrum planctonicum and St. pingue. A study of planktic évolution. Svensk

bot. Tidskr. 41 : 218-234.

1948 — Staurodesmus, genus novum. Bot. Notiser : 49-83.

1950 — Radiation of desmids, its origin and its conséquences as regards taxonomy and

nomenclature. Bot. Notiser : 299-327.

1952 — Evolutionary studies on the shape of the cell and of the chloroplast in desmids.

Bot. Notiser : 264-306.

1952 - Phytoplankton associations of Swedish lakes. Proc. 7th int. bot. Congr. Stockholm

1950 :828-829.

1954 — Açtinotaenium genus Desmidiacearum resuscitatum. Bot. Notiser : 376-426.

1955 -Some mesotrophic phytoplankton indicators. Verh. int. Ver. Limnol. 12 : 212-215.

1955 - L’authentique Staurodesmus dejectus (Bréb.). Compte-rendu Ville Congr. Int. Bot.

17 :128-129.

1955 -Peridinium gatunense Nyg. i Sverige. Svensk bot. Tidskr. 49 : 240-246.

1956 — On the variation of Micrasterias mahabuleshwarensis f. Wallichiu Bot. Notiser 109 :

260-274.

1957 - Some little known Swedish phytoplankters. Svensk. bot. Tidskr. 51 : 207-222.

1957 — Morphological investigations of asymmetry in desmids. Bot. Notiser 110 : 49-82.

1958 -Eulimnion, an original place of new forms. Verh. int. Ver. Limnol. 13 : 879-882.

1967 - The desmid genus Staurodesmus. A taxonomie study. Ark. bot., Ser. 2, 6 : 467-

629.

209

Georges DEFLANDRE (1897-1973)

Y. LE CALVEZ

Georges, Victor DEFLANDRE naquit à Dizy-Magenta (Marne) le 18 mars

1897. Il reçut de son père artiste-peintre et cheminot, de son grand-père paternel

organiste et compositeur ses dons artistiques : il dessinait fort bien et, excellent

musicien, jouait indifféremment de l’orgue et de l’harmonium, du piano et du

clavecin, du violon et du violoncelle. De son grand-père maternel, inventeur

d’une horloge électrique et artisan du premier wagon-dynamometre construit en

France, il hérita ses qualités d’observation, son amour de la recherche, son goût

de la découverte.

Obligé en 1913 d’interrompre ses études secondaires brillamment commen¬

cées, il devint employé du Chemin de fer, puis en 1915 instituteur. Mobilisé en

Rev. Algol, N. S., 1976, XI, 3-4 : 209-211.

Source : MNHN, Paris

210

Y. LE CALVEZ

1916, Georges DEFLANDRE, d’abord Aspirant, puis Sous-Lieutenant d’infan¬

terie, fut blessé et fait prisonnier en 1918. A son retour de captivité, il retrouve

son poste d’instituteur mais, désireux d’accroître ses connaissances scientifiques,

il reprend seul ses études et commence dès 1922 à fréquenter assidûment le La¬

boratoire de Cryptogamie du Muséum, dirigé par L. MANGIN. Tout le temps

que lui laisse ses obligations professionnelles, il le consacre à la recherche et, en

1926, il soutient sa thèse de Doctorat d’Université. Nommé en 1930 préparateur

à l’École Pratique des Hautes Études dans le Laboratoire de L. MANGIN, il est

en 1932 boursier à la Caisse Nationale des Sciences et accueilli au Laboratoire

d’Évolution des Etres Organisés. En 1943, l’École Pratique des Hautes Études

créait pour lui le Laboratoire de Micropaléontologie qu’il devait diriger jusqu’en

1967, et le C.N.R.S. lui conférait en 1953 le titre de Directeur de Recherche.

Plusieurs fois Lauréat de l’Académie des Sciences, Président de la Société Fran¬

çaise de Microscopie (1933), Fondateur et Directeur des Annales de Protisto-

logie (1928-1936), G. DEFLANDRE était membre d’Honneur de nombreuses

sociétés tant françaises qu’étrangères, Correspondant de l’Académie des Sciences

et Chevalier de la Légion d’Honneur.

L’œuvre scientifique de G. DEFLANDRE est immense et couvre l’ensemble

de la Micropaléontologie et de la Protistologie. Il n’est pas possible ici d’analyser

tous ses travaux, aussi me bornerai-je à donner un très bref aperçu de l’essentiel

de ses recherches consacrées aux Algues.

Lorsqu’en 1920 il commença à s’intéresser aux Algues microscopiques uni-

cellulaires des eaux douces, ce groupe était très délaissé et de nombreuses régions

de France restaient encore à explorer. G. DEFLANDRE en quelques années

apporta une contribution notable a la floristique de la France en publiant une

série de notes relatives d’abord aux environs de Paris, puis à la Basse Normandie,

enfin à la Bretagne, aux Vosges, aux Pyrénées et aux Ardennes. Au point de vue

morphologique et systématique, les Desmidiées tiennent une large place dans ses

recherches mais il ne néglige pas pour autant les autres Chlorophycées.

Puis, pendant de nombreuses années, G. DEFLANDRE va consacrer une gran¬

de partie de son activité à l’étude des Flagellés. Ses premiers travaux se rappor¬

tent aux Phytoflagellés et principalement aux Eugléniens dont il étudie la mor¬

phologie et la cytologie : sa monographie du genre Trachelomonas sera le sujet

de sa these et en 1959, il signalera l’existence des premiers Trachelomonas fossi¬

les dans un schiste bitumineux du Pliocène de Madagascar. Il se penche ensuite

sur les Silicoflagellés ou Flagellés siliceux et établit une nouvelle classification

des Chrysomonadines, créant pour 65 d’entre elles la famille des Archaeomona-

dacées. Il s intéresse aussi aux Ebriidés et publie de nombreux articles concer¬

nant leur morphologie et leurs tendances évolutives.

C’est en 1939 qu’il commence ses observations sur les Flagellés calcaires, avec

celles des Coccolithophoridés, aujourd’hui très étudiés, mais qui ne comptaient

alors qu un petit nombre de spécialistes. Là encore, il crée de nombreux genres,

espèces et la famille des Braarudosphéridés.

Dans le même temps, son intérêt se porte sur les microfossiles des silex cré-

Source : MNHN, Paris

Georges DEFLANDRE

211

tacés (Dino flagellé s, Hystrichosphéridés, etc.) et sur les Diatomées.

Tous ces travaux ont abouti à plus de trois cents publications, écrites dans un

style précis, clair, élégant et illustrées de dessins qu’il exécuta lui-même ou de

photographies dont il était l’auteur.

A côté de ces recherches originales qui ont fait de lui le grand précurseur de la

Micropaléontologie moderne, G. DEFLANDRE est l’auteur d’ouvrages de vulga¬

risation qui ont largement contribué à faire connaître l’existence des micro-orga¬

nismes : «La microscopie pratique» parue en 1930 et la «La vie créatrice des Ro¬

ches» publiée en 1941, traduite dans toutes les langues et dont la dernière édi¬

tion date de 1967.

Dans le traité de Zoologie (Directeur P. P. GRASSÉ), G. DEFLANDRE rédi¬

gea les chapitres relatifs aux Phytomonadines, aux Xanthomonadines, aux Ebrié-

diens, aux Silicoflagellés, aux Chrysomonadines fossiles, aux Coccolithophoridés,

aux Flagellés fossiles incertae sedis. Enfin, en collaboration avec Mme Marthe

DEFLANDRE-RIGAUD, sa femme, il publia au C.N.R.S. le Fichier Micropalé-

ontologique Général concernant tous les groupes de Protistes, et qui contient

plus de 4000 fiches se rapportant aux seules Algues.

Cet autodidacte, qui était à la fois Algologue, Protistologue, et Micropaléon¬

tologiste, et qui embrassa au cours de sa carrière scientifique le vaste domaine du

nannoplancton, était aussi un naturaliste complet. Sa grande érudition, ses dons

d’observation, sa connaissance des langues étrangères (il parlait couramment

l’anglais et l’allemand, traduisait l’italien et l’espagnol, et possédait des notions

de russe) le poussaient à s’intéresser à tout ce qui l’entourait et c’était un plaisir

de l’entendre commenter, toujours avec beaucoup d’esprit, telle ou telle idée

nouvelle, telle ou telle découverte récente.

En la personne de G. DEFLANDRE, la Micropaléontologie perd l’un de ses

plus éminents représentants. Son nom restera toujours attaché à cette discipline

et son œuvre est le témoin d’une vie toute entière consacrée à la Recherche et à

la Science.

Source : MNHN, Paris

213

THE ASSOCIATIONS OF ALGAE

ARTHROPODS - II *

WITH

U.GERSON **

6. DELETERIOUS EFFECTS OF ALGAE ON ARTHROPODS

6. 1 PHYSICAL INTERFERENCE

Several cases of algal growth on arthropods were noted above. Some appear

to be fortuitous, others serve to camouflage the hosts, and in additional ones, to

be discussed below, the algae parasitize the arthropods. The overgrowing plants

may also adversely affect the host through physical interférence. A pertinent re¬

port (GLYNN 1970) concerns algae growing on the marine isopod Dynamenella

perforata, causing it indirect harm by interfering with crawling, swimming, fee-

ding and other functions. BARNES and TOPINKA (1969) wrote that Fucus ini-

tially receives some protection from the barnacles on which it grows, but later

the plants kill the animais by interfering with their feeding activity.

Indirect physical interférence through decreasing transparency brought about

by increasing phytoplankton production in lakes and rivers was postulated by

FREY (1969) to affect populations of chydorid cladocerans. These animais

utilize rooted aquatic plants as their main substrate, and the greater and deeper

the area inhabited by the plants, the more varied the cladoceran populations. In

low-productivity water bodies the plants extend to deeper zones, due to the

greater transparency of the water. But with increased phytoplankton production

transparency decreases, the extent of rooted aquatic plants becomes restricted,

and consequently the number of cladoceran species déclinés.

6. 2 OXYGEN DEPLETION AND OVERPRODUCTION

The déplétion of oxygen in ponds by algae, or its overabundant production

there, are spécifie mechanisms whereby arthropod populations may be affected

* Part I : Rev. Algol, N.S., 1973 (1974), XI, 1-2 :18-41.

** The Hebrew University, Faculty of Agriculture, Rehovot, Israël.

Rev. Algol., N. S., 1976, XI, 3-4 : 213-247.

Source : MNHN, Paris

214

U. GERSON

(EHRLICH 1966). Chara fragilis was léthal to some mosquitoes apparently due

to excessive oxygen production (DARBY 1962). MARSHALL (1966) stated

that Daphnia suffered prénatal mortality when held in a Chlamydomonas culture

kept in the dark, possibly due to déplétion of dissolved oxygen by the algae. Wa-

ter trapped by large brown seaweeds (such as Fucus and Ascophyllum) at low

tide becomes déficient in oxygen during the night or on cloudy days (WIESER

and KANWISHER 1959). The lack of oxygen may paralyze or kill the arthro-

pods which usually inhabit these brown algae. Efforts to reduce the amplitude

of the diurnal oxygen curve in stabilization ponds so as to maintain Daphnia

populations which help in water clarification, were detailed by EHRLICH

(1966).

6. 3 INHIBITORY SUBSTANCES

SAUNDERS (1957) stated that there is some evidence for antagonistic

activity of algal populations towards microcrustaceans, often enhanced by re-

lease of a substance from ingested cells within the animais. A tannin which im-

mobilized the Sargassum epifauna was discovered by SIEBURTH and CONO-

VER (1965), the branch tips of the seaweed being observed to be virtually

free of the usual epibiota. Appropriate chemical tests suggested the causal factor

to be a tannin, which adversely affected copepods at dilutions up to 1 : 125,

but not at higher ones (SIEBURTH and CONOVER 1965). Some other ins¬

tances of this phenomenon were presented in reviews by LUCAS (1961) and

SIEBURTH (1968). The term «ectocrines» was coined by LUCAS (1947) to

dénoté biologically active excretory products of aquatic organisms that may

hâve effects in marine ecology. A pertinent example was presented by SIE¬

BURTH (1968). The brown alga Ralfsia verrucosa sécrétés some polyphenols

which kill barnacle nauplii, thereby preventing their settlement in pools where

the alga abounds.

6. 4 WATER BLOOMS AND TOXINS

The best known cases of toxin production by algae are those associated with

«water blooms». The causes and development of these phenomena were discus-

sed by LUND (1965), ROUND (1965), STRICKLAND (1965) and many others.

These great outbursts of algal growth are often associated with widespread poi-

soning of fishes, birds, crustaceans and even terrestrial animais, which may

suffer after drinking the waters (ROUND 1965). The pertinent literature was

recently summarized by SCHWIMMER and SCHWIMMER (1968) (but see also

VALKANOV 1964). Copepods, cladocerans, amphipods and decapods were

among the affected crustaceans.

RYTHER (1954) believed that in rapidly multiplying algal populations

some inhibitory substance («chlorellin») accumulâtes, which seems to exclude

the grazers (the basis for this postulate, HARDY’s exclusion theory, was discus-

sed in a former paragraph). Later writers (RIGLER 1961;TAUB and DOLLAR

Source : MNHN, Paris

ASSOCIATIONS OF ALGAE W1TH ARTHROPODS

215

1968, and others) criticized RYTHER and did not accept his chlorellin theory.

TAUB and DOLLAR (1968), for instance, explained Daphnia inhibition at high

algal concentrations by nutrient defïciencies rather than by toxic substances. A

case where an alga is poisonous to arthropods only in spécial circumstances was

described by STANGENBERG (1968). The plant was Microcystis aeruginosa,

which contains a toxic substance. When Daphnia and Eucypris were kept on

normal cultures, no mortality occured. But the toxin may be discharged from

the algal cells by refrigerating and defrosting them. Considérable copepod mor¬

tality took place when such refrigerated-and-defrosted cells were placed in the

cultures.

6. 5 THE BIOLOGICAL CONTROL OF MOSQUITOES BY ALGAE

Se ver al authors hâve remarked on the effect of Characeae and other algae on

mosquito larvae. FRITSCH (1956, p. 447) noted the frequent avoidance of

waters harboring these algae by the larvae, though there was no clear evidence

for the production of any larvicidal substances by the Characeae. REMUSAT

(1962) claimed to hâve experimental proof that the larvae disappear from Cha-

raceae-containing waters because of the algae. It is only one step from such

observations to utilizing them, i. e., manipulating the algae in order to control

insect pests biologically. A review of such projects was presented by FRANZ

(1961), who noted that most of these efforts were against mosquito larvae. The

best results were reported by GERHARDT (1953, 1955). This author noticed

that rice fields free from mosquito larvae supported rich blue-green algae, whe-

reas the pests abounded in fields with lesser algal growths. GERHARDT ( l . c.)

wrote on the algae employed, on their culture and on successful introduction

experiments. The green alga Oedogonium princeps is another promising agent for

the control of anopheline larvae (GHOSH and HAT1 1964). Other species may

also prove useful in this respect, and on the whole it seems that the utilization of

algae against insect (and other) pests which live in aquatic environements has

been rather neglected.

6.6 PARAS1TISM

Several algae are parasitic on arthropods, although it may sometimes be diffi-

cult to distinguish this association from the mere utilization of the animais as

substrates (discussed in section 5. 2). FRITSCH (1956) cites CHATTON’s work

on endoparasitic algae, including the généra Paradinium and Blastodinium. Mem-

bers of the latter genus castrate their copepod hosts (SEWELL 1951) and sex re¬

versai in an attacked animal was reported by CATTLEY (1948). Many Euglenoi-

dina were recently described as parasites of fresh-water copepods (MICHAJLOW

1966, 1968, etc. ). The parasites attack the eggs and intestines of the hosts,

often causing their death. In some cases the parasites begin their development in

the nauplial eye and then spread to other parts of the body (MICHAJLOW

1966).

216

U. GERSON

6.7 ENTANGLEMENT

This mechanism was reported in regard to fïshes, not arthropods, but it is per¬

tinent to note it here. The water net, Hydrodictyon reticulatum, is a colonial

alga whose cells become 4-5 mm long, forming a network with a mesh size of

6-8 mm in older plants. The colony forms a sac measuringup to 50 mm in diameter

and 200 mm in length (LEWIS 1961).Manysmall£ishesbecomeentangledin thenet,

and, if unable to free themselves, they eventually die there.LEWIS (/.c.) thoughtthat

the alga may indirectly dérivé nutrients from the decaying fish, exerting a signifi-

cant effect on small fish and fïngerling populations. It is quite likely that some

of the larger aquatic arthropods may similarly become entangled.

6. 8 INDIRECT EFFECT OF HYDROLYZED SEAWEED

Some reports hâve been published in recent years concerning the indirect, ad¬

verse effects of algae, as hydrolyzed seaweed, on arthropods pests of agricultural

crops. Some of the daims in these reports may hâve commercial undertones, but

it seems worthwhile to note them in the présent context. STEPHENSON (1966)

stated that liquified seaweed, marketed as «Maxicrop» in the United Kingdom,

may confer on broad beans, sugar beets and potatoes some résistance to infesta¬

tion by aphids. The résistance was considered to be behavioral rather than nutri-

tional, as the aphids (some of which are important plant virus vectors) were wan-

dering restlessly on the plants. Maxicrop was also reported to protect orchard

trees against infestation of red spider mites (Tetranychidae), almost like com¬

mercial pesticide treatments. The seaweed product appeared to hâve the additio-

nal advantage of continuously building up its effect, so that after 2-3 years the

degree of control achieved was as good or better than that obtained by conven-

tional acaricides. These effects were thought to be due to the enhanced effect

of predators, which were unaffected by Maxicrop (STEPHENSON, l. c.).

The mecanisms protecting the Maxicrop-treated plants against these pests are

not clear, but it is beleaved that the effect is mediated through the plants, and

that it is not insecticidal (STEPHENSON 1966). Growth-regulating properties

were also claimed for Maxicrop, and these may be involved in protecting the

plants (BOOTH 1969).

A case of historical interest, concerning an attempt to protect potato plants

from «potato bugs» with the help of algae, was related by SCHWIMMER and

SCHWIMMER (1968). «Green lake scum» was applied to the potatoes, apparen-

tly to control the bugs. As a resuit both potato plants and bugs died.

7. ALGA-ARTHROPOD COMMUNITIES

7.1 COMMUNITIES ON SEAWEED AND ON FRESHWATER ALGAE

Certain arthropods hâve been associated with algae for prolonged periods, du-

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

217

ring which they formed some spécifie communities. One such community is

attached to Sargassum seaweed in the Sargasso Sea. This plant, originally coming

from the coasts of the Caribbean and covering large areas in the Sargasso Sea,

affords the base for a nomadic fauna of littoral origin, presumably stemming

from the home of the seaweed (ALLEE and SCHMIDT 1951). There are only 16

animal species directly attached to this Sargassum. The animais had to undergo

several adaptations in order to survive on this pseudobenthos, adaptations which

include specialized attachment behavior, nest building and protective coloration.

There are some arthropods among them, such as the crab Planes minutus and the

shrimps Leander tenuicornis and Latreutes ensiferus (ALLEE and SCHMIDT

1951). A note of historié interest may be inserted here again. As Columbus was

Crossing the Atlantic in 1492, his crew observed seaweed floating by, with a

crab attached to it. This sight suggested the proximity of land to the sailors, but ac-

tually they were only about midway across the océan, sailing through the Sar¬

gasso Sea (BERRILL 1966).

ANDREWS (1945) recognized several faciations of algae and animais inhabi-

ting kelp beds in the sea near the coast of California. Arthropods are involved

in two of these faciations, one of which consists of Macrocystis and the decapod

Pugettia, and appears to be seasonal. Nereocystis and the amphipod Amphithoe

make up the other faciation which is permanent throughout the year. Assembla¬

ges of algae and ostracods were distinguished by WHATLEY and WALL (1969)

in the Southern Irish Sea. The laminarian assemblage was exclusively found on

the holdfasts of Laminaria digitata and L. hyperborea, and its dominant ostracod

was Loxoconcha rhomboidea. The littoral assemblage was dominated by Cy there

lutea and Heterocythereis albomaculata, and occured on Cladophora, Entero-

morpha and Corallina, but never on Laminaria. A Fucus serratus community,

which includes many alga-feeding arthropods, were postulated to exist near the

Swedish coast by HAGERMAN (1966). This author also noted that the alga’s

surface has a pronounced effect on the associated fauna, filamentous, scrub-like

dgae having richer faunae than leaf-like ones. Similar observations were recorded

by JANSSON (1967), WHATLEY and WALL (1969) and others.

7. 2 COMMUNITIES LIVING IN SEASHORE WRACK

BACKLUND (1945) conducted an extensive study of the faunae occuring

in seashore wrack on Scandinavian shores, listing many arthropods. Later litera-

ture on this subject was reviewed by STRENZKE (1963), in the introduction to

his experimental study of arthropod succession in seaweeds. This investigator

placed fresh Fucus and Enteromorpha in open wire baskets near the seashore,

and studied the arthropods occuring therein for a period of one year. Four dis¬

tinct faunistic phases, correlated with sodium chloride content, were observed.

In the initial, colonizing phase, during the first fortnight of sampling, the antho-

myiid fly Fucellia intermedia and the mesostigmatic mite Halolaelaps marinus

predominated. Little decay occured during this phase, nor were there any signi-

ficant changes in the NaCl or water content. The second, «decayed matter» pha¬

se lasted from the third week to the beginning of the fourth month, and the do-

218

U. GERSON

minant arthropods were the spheroceriid Aies Limosina spp. and the mite Halo-

laelaps celticus. NaCl content was still above 10%. During the third, «transitio-

nal» phase, the sait concentration fell to below 2%. This phase lasted up to 7-8

months from the experiment’s beginning, and the more abundant animais were

certain Aies, such as the syrphid Syritta and the scatopsid Scatopse. The final

phase was characterized by large numbers of the mosquito Trichocera and the

collembolan Hypogastrura. Water content was believed to hâve an important

modifying effect on this succession (which could be replicated during several

years), but the dominant factor was considered to be sodium chloride content.

Additional work along the same Unes has more recently been reported by

MOELLER (1967), who found that Collembola, which tend to avoid high salini-

ty conditions, hâve no effect on algal décomposition. YONGE (1949) considered

the seaweeds to represent a «factor of the first importance» in the lives of many

shore animais (arthropods included). Other observations on intertidal, kelp-uti-

lizing insects were recorded by EVANS (1968), who also summed up many of

the previous reports. One group which deserves spécial mention is the dipterous

famüy Coelopidae, the seaweed or kept Aies. These insects, occuring the year

round in seashore wrack, spend their entire lives therein, as it provides them

with a warm, humid environment and with the nourishing slime upon which the

larvae feed (OLDROYD 1964).

The possible significance of seaweed banks as sites where the transition of

animais from aquatic to terrestrial habitats could take place was discussed by

LAWRENCE (1953). This author studies the cryptic soil arthropods of South

African forests and noted that many of these animais had relatives able to live

in the littoral. He believes that many archaic arthropods, in their attempts to live

on land, initially colonized the intertidal zone where heaps of seawrack could

afford them temporary shelter. Thus LAWRENCE (/. c.) thinks that seaweed

beds, with their perpetually-moist interiors, might serve as terrestrial outposts

for the colonizing arthropods eventually destined to live in forest soil. This theo-

ry was also discussed by KUEHNELT (1961), who did not however accept it.

7.3 COMPETITION FOR SETTLING SITES

Intertidal zones are sometimes the scene of compétition for settling sites

between arthropods (such as barnacles) and algae. A universal System of zona¬

tion for the area between tide-marks on rocky coasts was introduced by STE-

PHENSON and STEPHENSON (1949), who designated the middle part of the

shore as the Balanoid zone. Various algae, among them fucoids, are known to

interfère with the barnacles there. One such scene was described by RIGG and

MILLER (1949) from the vicinity of Neah Bay, Washington, U.S.A. The ani¬

mais were usually more successful in occupying the available sites, often comple-

tely crowding out the algae to the very borders of the barnacle colonies. In other

areas algae gained additional anchorage by pushing their holdfasts among the

animais. On the other hand, the latter were sometimes restricted to narrow belts

above the algal beds, as the plants were apparently better adapted to the imme-

Source : MNHN, Paris

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

219

diatly-adjacent vertical ranges (RIGG and MILLER 1949).

Germlings of Fucus vesiculosus attach onto barnacles and clams better than

onto rocks, but their holdfasts are also easier to detach from the former surface.

Fucus subsequently kills the barnacle on which it grows, and the empty shell

with its algal growth is devoured by grazing limpets. These interactions were

shown by BARNES and TOPINKA (1969) to affect the compétition for space

between barnacles and algae.

In exposed areas Fucus is less abundant than barnacles, as the alga often deta-

ched by wave action before attaining a size sufficient to kill the animais. With

decreasing exposure the algae succeed in developing bigger plants, subsequently

killing the barnacles (which are then removed by limpets). As a resuit the shel-

tered areas become available for further colonization by the algae, which grow

on other substrates and deny access to invading barnacles. Additional observa¬

tions on this subject were reported by MACFARLANE (1952) and GLYNE

(1965) published an extensive study on algal-barnacle relationships and com-

inunities. Compétition between algae and other arthropods - simuliid larvae - for

space on rocks was reported by FEE (1967).

7. 4 COMMUNISTES AFFECTED BY TECHNOLOGICAL CHANGES

Modem technology is bringing about many changes in algal distribution and

.bundance (and presumably in their associated arthropod fauna), and some re¬

présentative cases will be noted. The hulls of present-day fuel tankers are generally

free of animal fouling forms, apparently because of the ships’ fast movement

from tropical, warm seas to temperate waters. While this wide range of environe-

mental conditions largely excludes animal foulers, it is highly favorable to cer-

ain algae, especially Enteromorpha (EVANS and CHRISTIE 1970). It may be

redicted that this fouling alga, currently invading a new habitat, will eventu-

lly be found to hâve its own characteristic associated arthropod fauna on the

rnkers’ hulls.

Lake Kariba in Central Africa is an artificial lake created in 1958 by damming

ie Zambezi River. Submerged trees serve as a newly-created substrate for ani-

:als (including arthropods) in this lake. The richest faunal standing crop was

>und where benthic algal populations were well developped (McLACHLAN

970). In this case alga-arthropod communities are also evolving on a new and

rtificial substrate, but probably in the pattern they follow elsewhere.

Another example pertains to terrestrial epiphytic algae. ELTON (1966) noted

liât Pleurococcus viridis appears to be relatively résistant to industrial soot pol-

ution in England, thus sometimes remaining the dominant epiphyte on tree

runks. Many arthropods dépend on various epiphytic algae and lichens for food

BROADHEAD 1958; ELTON 1966). The relatively recent dominance of Pleu-

ococcus will eiuher exclude the animais which cannot utilize this alga, or make

them change their diet.

Source :MNHN. Paris

220

U. GERSON

The effects of pollution and its often resulting eutrophication of waterways

and lakes on algae and their grazers hâve been discussed by various authors; a

useful summary was presented by BROOKS (1969).

7. 5 SOME GEOLOGICAL ASPECTS OF ALGA-ARTHROPOD ASSOCIA¬

TIONS

The frequent concomitant occurence of algae and arthropods in fossil beds

attests to their manifold associations in the geological past. Algae hâve an affi-

nity for silica, transforming it to the colloidal State, in which animais may be

trapped. The resulting fossils are silicifïed arthropods which occur in calcareous

lakebed nodules (PIERCE 1961).

The évolution of animais which feed on and burrow in algae was believed by

GARRETT (1970) to hâve caused the décliné of stromatolites. These are lami-

nated structures built by dense mats of blue-green algae which selectively trap

and bind sédiment particles among their mucilaginous filaments. Stromatolites

abounded in the Precambrian and declined from the Ordovician to become

scarce in the Cenozoic. GARRETT (/. c.) suggests that this décliné can probably

be correlated with the évolution of new grazing and burrowing animais which

began to appear during the Ordovician expansion. Further, the available geolo¬

gical data indicate that stromatolites and animais are usually mutually exclusive.

To support his arguments, GARETT (/. c.) présents evidence that grazing and

burrowing animais (gastropods, polychaetes, fishes and some arthropods such as

shrimps and crabs) may prevent the formation of mats of blue-greens and des-

troy algal laminations.

Past periods of increasing phytoplankton production and lake eutrophication

were deduced by FREY (1964) from changes in cladocerans occuring in Quater-

nary sédiments. Bosmina longirostris is considered to be characteristic of more

productive situations, and its replacing B. coregoni is thus considered evidence

for increasing productivity in the water bodies whose sédiments were studied.

Although FREY later (1969) expressed some réservations about his interpréta¬

tions, the method still appears to be rather suitable for similar reconstructions.

Such an effort was made by SEBESTYEN (1969), who postulated past changes

in the water level of Lake Balaton (Hungary) from the relative abundance of the

alga Pediastrum and of cladoceran remains in lake sédiments. As the alga is belie¬

ved to be planktonic, its greater abundance (relative to Cladocera) indicates past

periods during which a high water level persisted, with a corresponding domi¬

nance of planktonic life. The relative dominance of the Cladocera in the sédi¬

ments, on the other hand, would suggest decreased water level periods during

which benthic life was more abundant.

Past associations between arthropods and algae may hâve some bearing on the

origins of oil, as discussed in section 2. 4. A different link was suggested by 10-

VINO and BRADLEY (1969). These authors found that the ooze in Mud Lake,

Florida, consists exclusively of minute faecal pellets produced by larvae of the

Source : MNHN, Paris

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

221

fly Chironomus whilst feeding on blue-green algae. The résultant pelletai ooze

appears to be similar to lacustrine organic ooze believed to be the precursor of

rich oil shale beds in North America. The analogy between the lacustrine copro-

pel of Mud Lake and Eocene oil shale precursors is enhanced by the discovery of

minute faecal pellets in thin sections of oil shale, and of immature chironomid

remains in rich oil shale beds.

8. EFFECT OF PESTICIDES

8. 1 EFFECT OF ALGICIDES ON ARTHROPODS

Many herbicides are currently being used to control algae in various habitats

(MULLIGAN 1969). Copper sulfate, among the better known and more widely

used compounds, is toxic to Daphnia and other aquatic arthropods (FISHER

1956; ROSE 1954). The toxicity of various aquatic herbicides to Daphnia was

avaluated by CROSBY and TUCKER (1966), who concluded that several of

these compounds may présent a hazard to various major organisms in the food

chain.

8. 2 EFFECT OF INSECTICIDES ON ALGAE

Insecticides may reach the algae in their aquatic or terrestrial habitats both

ntentionally an unintentionally. In the former case, the Chemicals are applied

iirectly, to control arthropods grazing on algae (RAGHU and MACRAE 1967),

rustacean parasites of commercial fish (LAHAV and SARIG 1967) or flies bree-

ling in washed-up seaweeds (MARX 1967). Unintentionally, insecticides reach

lgae through runoff or drift from treated areas. The various responses of diffe-

ent algae to insecticides were discussed by several authors. MENZEL, ANDER-

ON and RANDTKE (1970) showed that three chlorinated-hydrocarbon pesti-

ides vary greatly in their effects on four species of marine algae. The most sensi-

ive of these, Cyclotella nana, was inhibited in its photosynthetic activity and in

ts growth by concentrations as low as 0.1 -1.0 parts per billion. Dunaliella

ertiolecta, on the other hand, was completely insensitive, and the other two

pecies were intermediate in this respect. The possibility that the differential

ffect of pesticides may affect the succession and dominance of certain algae was

Iso discussed by MENZEL et al. (1970). Additional insecticides were similarly

ested by MOORE and DORWARD (1968), who also found that various algae

vere differently affected by these Chemicals. Malathion, an important organo-

’hosphorous insecticide, was quickly metabolized by some algae, a finding

vhich led to the conclusion that these plants may be important factors contri-

mting to the disappearance of pesticides from natural communities. The use of

dgae as pesticide indicators was advocated by MOORE (1967), though CHOL-

NOKY-PFANNKUCHE (1969) warned against generalizations obtained from

ûoessay tests with these plants.

222

U. GERS ON

Some algae which may be quite résistant to insecticides appear capable of

biologically concentrating these compounds in their bodies (VANCE and

DRUMMONS 1969). The crustacean suspension feeders, in their turn, also con-

centrate such substances from their algal food, and may thus ingest and accumu-

late high insecticide doses. Generally, the aquatic arthropods are far less insecti-

cide-resistant than are the algae. The danger of such poisoning and its effect on

the food chains in the océans was noted by MARX (1967).

9. DISCUSSION

9. 1 THE SCARCITY OF SYMBIOSIS

Apparently the only arthropods so far reported to hâve symbiotic or mutua-

listic associations with algae are damsel fly naiads (SELVARAJ and JOB 1965;

WILLEY et al. 1970) and chironomid larvae (BROCK 1960). One thus becomes

aware of what is perhaps the outstanding feature of the associations between

algae and arthropods, namely, the extreme scarcity of symbiosis between these

two groups of organisms. Both groups hâve many times evolved symbiotic rela-

tionships with représentatives of other phyla. The insects (to mention the domi¬

nant arthropod class) hâve bacteria, yeasts and fungi as their plant symbionts

(BUCHNER 1965). Various symbiotic alage hâve Protozoa, Porifera, Coelente-

rata, Ctenophora, Rotatoria, Platyhelminthes, Annelida, Mollusca, Echinoderma-

ta and Tunicata as their animal hosts (DROOP 1963; McLAUGHLIN and ZAHL

1966). No arthropod host for algae was listed by any of these authors, nor has a

symbiotic alga been recorded as présent within an arthropod host by BUCHNER

(1965).

Though one is at a loss to explain the rareness of symbiotic relationships

between algae and arthropods, several ideas corne to mind. The foremost is that

so few of these associations hâve been recorded simply because they hâve not

yet been discovered. McLAUGHLIN and ZAHL (1966) noted that additional

alga-bearing animais are constantly being reported. Further, as DROOP (1963)

remarked, tropical animais, which hâve higher rates of metabolism than their

temperate-zone counterparts, may hâve a greater need for the complementary

services of symbiotic algae. It is just these tropical arthropods which are the less

known, and it is among them that additional symbiotic relationships with algae

may be found. The recent reported instances of arthropod-algal symbiosis

(SELVARAJ and JOB 1965; WILLEY et al 1970) lend support to the

argument that many symbiotic associations remain undiscovered.

Another possibility is that algal symbiosis has, in fact, evolved in some ar¬

thropods, but as these became extinct, the relationship died out.

DROOP (1963) noted that, despite the occurence of algal symbiosis in ani¬

mais representing many phyla, few algal types participate in these associations,

the commonest being zoochlorellae of the genus Chlorella. This suggested to

DROOP (/. c.) that few algae are sufficiently tolérant to their hosts to be able to

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

223

Uve within them. The lack of enough algal candidates for symbiosis may thus

contribute to their scarcity in arthropods. And even algae capable of such asso¬

ciations may require a change in host résistance through some weakness in order

to become establish^d. A recent case ofhuman algal infection is pertinent in this

respect. KLINTWORTH, FETTER and NIELSEN (1968) reported on a case of

human cutaneous infection caused by Prototheca wickerhamii, an achloric alga

which sometimes occurs saprophytically on animais and men. The patient, suffe-

ring from diabètes mellitus and breast cancer, was under heavy drug treatment.

To explain the pathogenic occurence of Prototheca, KLINTWORTH et al. (/. c.)

postulated that both the disease and the drugs altered and lowered body résis¬

tance, thus enabling the alga to become cutaneously established. It is of interest

to note that Prototheca «appears to be no more than a colorless Chlorella »

(FRITSCH 1956), the commonest symbiotic zoochlorella.

A different factor contributing to the scarcity of algal-arthropod symbiosis

may be the production of inhibitory substances by the algae : see reviews by

LUCAS (1961) and SIEBURTH (1968). It is noteworthy that some coral zoo-

xanthellae produce terpenes which inhibit and exclude other animais (Mc-

LAUGHLIN and ZAHL 1966).

Whatever the validity of these spéculations (and admitting that they do no-

ching to explain symbiosis between algae and other animais), the scarcity of

algal-arthropod symbiosis remains an unexplained biological phenomenon.

9.2 A PROPOS AL FOR ALGAL MANAGEMENT

This survey of algal-arthropod associations has shown that algae may be both

bénéficiai and harmful . They are involved in sewage treatment and enrich the

soil with nitrogen, they form the base of the great food chains in the océans (and

some fish ponds) and are utilized for many commercial purposes. On the other

hand, algae cause «water blooms» that are sometimes toxic, and the «decay» of

water bodies (FERGUSON 1968); they are weeds in kelp beds (CHENG 1969)

and even pests of woody plant cuttings (COORTS and SORENSON 1968) and

cea and coffee crops (FRITSCH 1956). For a detailed «algal ledger», presenting

the crédits and débits of algae, see PRESCOTT (1969).

The above présentation is intended to convey the idea that a greater effort

;hould perhaps be made to manipulate algal populations. The harm algae do may

>e reduced or, conversely, their bénéficiai effects can be enhanced. The poten-

ial of algae as biological control factors has hardly been tapped, and the possibi-

ity of biologically suppressing algal pests is still only a suggestion (MULLIGAN

1969). Such manipulation obviously calls for an interdisciplinary attack on algal

ecology (SIEBURTH 1968), for better management of algal resources or, to use

a term currently in vogue, for algal management. (The term was recently intro-

duced in a more restricted sense by MULLIGAN 1969). Evidently the préserva¬

tion and manipulation of algal resources is to be but part of the préservation of

ail marine and freshwater resources, as advocated by various authors (i. e., MARX

1967). However, because of the dual potential of algae, their ability to be both

224

U. GERSON

bénéficiai and harmful, some spécial measures are needed, and hence this pro¬

posai for algal management.

AC KNO WLEDGMENTS

Dr. D. K. McE. KEVAN Chairman, Department of Entomology, MacDonald College of

McGill University, critically reviewed the manuscript, added some references and permitted

me to use unpublished personal observations. Dr. F.E.A. CUTTEN, also of MacDonald Col¬

lege, likewise made useful suggestions. Dr Ralph A. LE WIN, of Scripps Institution of Ocea-

nography, read the first draft of the manuscript and offered some useful critical comments.

Drs D. KAHAN and M. RAHAT, both of the Hebrew University of Jérusalem, made several

helpful suggestions. I wish to express my gratitude to ail of them.

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USINGER, R. L., and KELLEN, W. R., 1955 - The rôle of insects in sewage disposai beds.

Hilgardia 23 :263-321.

VALKANOV, A., 1964 — Untersuchungen über Prymnesium parvum Carter und seine

toxische Einwirkung auf die Wasserorganismen. Kieler Meeresfor. 20 : 65-81.

VAN LANDINGHAM, S. L., 1964 - Some physical and generic aspects of fluctuations

in non-marine plankton diatom populations. Bot. Rev. 30 : 437-478.

VANCE, B. D., and DRUMMOND, W., 1969 - Biological concentration of pesticides by

algae. Amer. Water Works Ass. J. 61 : 360-362.

WALL WORK, J. A., 1967 - Acari. In A. Burges and F. Raw (eds.), «Soil Biology». Aca¬

demie Press, London.

WEBB, K. L., and JOHANNES, R. E., 1969 - Do marine crustaceans release dissolved

amino acids t.Comp. Biochem. PhysioL 29 : 875-878.

WEBBER, H. H., 1968 - Mariculture. BioSci. 18 : 940-945.

WHATLEY, R.C., and WALL, D. R., 1969 - A preliminary account of the ecology and

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«The Taxonomy, Morphology and Ecology of Recent Ostracoda». Oliver & Boyd,

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WHITNEY, J. O., 1970 - Absence of sterol biosynthesis in the blue crab Callinectes sapidus

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237.

WIESER, W., and KANWISHER, J., 1959 - Respiration and anaérobie survival in some

seaweed-inhabiting invertebrates. Biol. BulL 117 : 594-600.

WILLEY, R. L., BOWEN, W. R., and DURBAN, E., 1970 -Symbiosis between Euglena

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WILLIAMS, L. G., 1947 - A comparative size study of the mole crab, Emerita talpoida

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204-207.

WIMPENNY.R. S., 1966 - The Plankton of the Sea. Faber and Faber, London.

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Source : MNHN. Paris

234

U. GERSON

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THE ASSOCIATIONS OF ALGAE WITH ARTHROPODS

ADDENDUM

U. GERSON

Many additional papers and books which discuss various aspects of the asso¬

ciations between algae and arthropods hâve become available since the prépara¬

tion of this article. Only the more relevant ones will be noted, arranged under

he same section headings and in the same order.

1. INTRODUCTION

A review on the associations between lichens and arthropods was prepared

md published (GERSON 1973) whilst awaiting publication of the présent paper.

. 2 SEASONAL, DIURNAL AND STAGE-DEPENDENT FEEDING

DEONIER (1972) reviewed the algophagus habits of adult shore Aies (family

Ephydridae). These Aies use their prestomal teeth to scrape algae off the sub-

trates, leaving dépréssions in the algal mats.

JOSEPH (1974) reported on the effect of tidal rhythm on the feeding acti-

ity of Hyale hawaiensis. This intertidal amphipod feeds on the green alga

nteromorpha compressa, feeding being most intense at high tide, as the algal

>elt becomes covered by rising water. Ebb entails decreased feeding. This rhyth-

nic phenomenon is believed (JOSEPH, l. c.) to be caused by the inhibitive effect

of depleted oxygen caused by algal respiration.

2. 3 AL G A-A RTH ROP OD FOOD CHAINS

The book «Marine Food Chains», edited by STEELS (1970), contains some

relevant papers on marine arthropods. CUMMINS (1973), in his review on

trophic relations of aquatic insects, notes various alga-feeding species.

236

U. GERSON

2. 5 PHYTOPLANKTON-ZOOPLANKTON INTERACTIONS

ESAIAS and CURL (1972) conducted grazing experiments with 3 species

of bioluminescent dinoflagellates and 3 calanoids. Ingestion rates were lowest

for the highly bioluminescent dinoflagellates. The authors attach considérable

survival value to the dinoflagellates’ flashes of light, postulating that these flashes

serve to defend their emitters by startling and confusing copepod grazers.

ESAIAS and CURL (Z. c.) further believe that this bioluminescence, by causing

sélective feeding, could be a factor in the formation of red tides and permanent

blooms of biolumenescent dinoflagellates.

2. 8 REARING ARTHROPODS ON ALGAE UNDER CONTROLLED CON¬

DITIONS

Various laboratory studies hâve recently been published on the effects of di¬

verse algal diets on aquatic arthropods (ARNOLD 1971; BATTAGLIA 1970;

BETOUHIM-EL and KAHAN 1972; NASSOGNE 1970; SCHINDLER 1971,

and others). The results of these studies support the opinion that increasing the

number of algal species in culture media enhances the survival rate of more ar¬

thropods species. This is due to the considérable selectivity exercised by the ar¬

thropods (mainly copepods) in regard to the species of algae available, their size

and concentration. SCHINDLER (1971) expressed the opinion that phyto-

plankton-zooplankton corrélations, often used to show relationships, are défi¬

cient whithout a better understanding of feeding relationships between algae

and their grazers.

2. 9 THE UNSUITABILITY OF SOME ALGAL DIETS FOR ARTHROPODS

The algae Anacystis nidulans, Merismopedia sp. and Synechocytis sp. showed

some toxicity or inhibition toward Daphnia pulex when offered as food (AR¬

NOLD 1971). Calanus helgolandicus releases most of its daily captured ration of

the diatom Biddulphia as undigested foodstuff (CORNER, HEAD and KIL-

VINGTON 1972). The reason is not known; explanations offered include dif-

ficulties in diatom cell assimilation or possible inhibitory substances présent

therein. Best growth rates of the harpacticoid copepod Euterpina acutifrons

were obtained with algal cells of medium size (7-16 pm) (NASSOGNE 1970).

Smaller (6-7 pm) or wider (> 16 pm ) algae gave lower rates or did not support

adult survival; algal food size may therefore be a limiting factor for these arthro¬

pods. Somewhat similar observations were reported by WINTERBOURNE

(1971) in regard to larvae of the caddisfly Banksiola crotchi. They feed on

stripes which they scrape from filamentous algae. As these larvae cannot digest

unbrocken algal cells, algae with broad and long cells constitute the food best

utilized; stripes from such algae hâve the highest ratio of brocken to unbrocken

cells. On the other hand, algae with small cuboidal cells, such as Hyalotheca,

constitute inefficient diets (WINTERBOURNE 1971).

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

237

PORTER (1973) conducted experiments on differential grazing by crustacean

zooplankton on a natural phytoplankton community in Fuller Pond, Connecti¬

cut, U.S.A.. From her results PORTER (1973) concluded that, by their response

to grazing, algae can be divided into three major groupings that eut across taxo¬

nomie Unes. One group contains large, rare or filamentous species which are

either unavailable to the grazers or actively rejected. Algae in the second group

are small and edible, while those in the third are encased in thick gelatinous

sheaths. Such algae pass intact through the ahmentary System of their grazers,

coming out in viable condition. Consequently, algae in the first group remain un-

affected by such grazers, those in the second decrease in numbers, and species

in the third group increase (through fragmentation and competitor suppression).

Data on the protection afforded bioluminescent dinoflagellates against

copepod grazers (ES AI AS and CURL 1972) were noted in the addendum to

section 2. 5.

2. 12 ARTHROPODS AS PESTS OF ECONOMICALLY-IMPORTANT AL¬

GAE

The periodical Nova Hedwigia has devoted its Heft 32 to «The biology of

riant Kelp Beds (Macrocystis) in California», edited by W. J. NORTH (1971).

t contains several papers on kelp grazers, including arthropods.

The manipulation of arthropods for the biological control of some seawed

ests was suggested by MANN (1973). Sea urchins ( Strongylocentrotus spp.)

aze heavily on seaweed and kelp in many parts of the world. MANN (/. c.)

ostulated that recent sea urchin outbreaks were triggered by réductions in the

opulations of their predators. The lobster Homarus americanus is considered to

e the key sea urchin predator in eastern Canada. Its numbers were seriously

:duced through human activity, and MANN (1973) advocates the protection

nd augmentation of lobster populations for the purpose of sea urchin control.

. 1 FEEDING ON ALGAE IN THE INTERTIDAL ZONE

The thysanuran Petrobius brevistylis lives in rock crevices along the beach,

here it feeds on Pleurococcus (LARINK 1968). Grapsid crabs were reported

y GRIFFIN (1971) to feed on red and green algae, which they scrape off the

irface of rocks in Tasmania.

.2 FEEDING ON SOIL ALGAE

The collembolan Hypogastrura viatica feeds exclusively on uniceUular algae,

vhich are very abundant in the upper soil layers where it Uves. Subsoil algae be-

ome available to Hypogastrura through the burrowing activities of other insects,

uch as beetles and fly maggots (KRAAN and VREUGDENHIL 1973). RAPO-

’ORT and TAGLIABUE (1964) applied dried and ground littoral algae as soil

238

U. GERS ON

fertilizer, and noted first a decrease and subsequently an increase in soil arthro-

pod populations. The authors believe this increase to be due to the enhanced

fecundity of algae-feeding arthropods as well as to attraction of outside animais

to the new and abundant food source.

WHEELER, HAPP, ARAUJO and PASTEELS (1972) isolated a pygidial

sécrétion from the staphylinid beetle Bledius. One or more components of

this sécrétion may regulate the growth of algae which flourish within the bur-

rows of Bledius and upon which the beetles feed.

4. 1 CASE AND TUBE CONSTRUCTION

The importance of algae in the behavioral ecology of the shrimp Alpheus cly-

peatus was pointed out by BOWERS (1971). He found that the algal tubes

which the animais construct play a significant rôle in their pair formation and

species spacing within the habitat. Presence of algae curtailed the shrimps’ ag-

gressive behaviour whilst enhancing the survival rate of their heterosexual pairs.

BOWERS (/. c.) concluded that algal tubes provide the basis for a territorial

social system which 1) allows the shrimps a higher population density, 2) increa-

ses the exploitable surface of their habitat.

4.3 SUBSTRATE AND SHELTER

WALLNER (1935) published an hitherto unnoticed paper on interactions

between lime-depositing algae and chironomid Aies. He concluded that the pre

sence of such algae enables the flies to initiate their colonization of fast-flowing

streams. BROCK (1970), in his review on High Température Systems, included

several instances of arthropods which live in algal mats in relatively hot (ca.

40 C) waters. A new method for mass- rearing the dipteran Chironomus riparius

was described by CREDLAND (1973), a method based on the availability of

more larval settling sites on filamentous algae maintained in plastic tanks. BAR

NARD (1972), who collected amphipods in New Zealand, noted that Caulerpa

beds were especially rich in these animais, whereas Hormosira was generally a

poor refuge for amphipods.

Tropical floating marine algae were observed by TEETER (1973) to accom-

modate some ostracods. These findings suggest an explanation for the trans

oceanic dispersai of ostracods within tropical latitudes (TEETER, Z. c.). Another

mode of ostracod dispersai may be while attached to sections of algae floating

in water taken into bilge tanks of oil tankers and bulk-carrying ships during

ballasting while sailing across the Panama Canal (TEETER 1973).

5. 1 NUTRIENT REGENERATION

CORNER and DAVIES (1971) reviewed the rôle of plankton in the nitrogen

and phosphorus cycles taking place in the sea, and included diverse algal-arthro-

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

239

pod grazing relationships. BROCK (1970) noted that colonization of algal mats

by ephydrid Aies promotes mat mineralization, usually a rather slow process.

The shells of diitoms ingested by some copepods are voided while encased

within a membrane which protects the enclosed diatoms from dissolution during

their descent to océan floor (SCHRADER 1971). These pellets sink many times

faster than a single shell, thus rapidly transporting silica from surface water to

deeper layers. The process may deplete the upper waters of silica (and other

nutrients), while delivering an abundance of this minerai to the océan floor.

Such excess extraction drives surface water toward undersaturation, until solu¬

tion rates on the océan floor provide the necessary balance for equilibrium of

silica réservoirs in the océan (SCHRADER, l. c.).

5. 3 MUTUALISM AND SYMBIOSIS

WILLEY (1972) described the cycle of the euglenoid Colacium which inha¬

bits damsel-fly hindguts in an interdunal pond in Indiana, U.S .A. During fall

Colacium flagellâtes enter the insects’ rectum by swimming directly through the

anus. The alga later sécrétés a gelatinous material by which it is held to the rec¬

al walls. Large Colacium colonies are then formed, which occur in the rectum of

he damsel-fly naiads as green plugs, easily seen through the hosts’ abdominal

valls. In spring some Colacium cells leave the host organ with fecal pellets, but

nost are ejected with the rectal cuticle as it is cast off during molt. Damsel-fly

iaiads are not reinfected prior to emerging as adults.

Other observations on Colacium were published by ROSOWSKI and KU-

RENS (1973). These authors were mainly concerned with the formation and

orphology of attachment material, an important character in the taxonomy of

olacium. They suggested that structure and formation of attachment material

roduced by copepod-colonizing Colacium may be affected by concentrations

f trace éléments in the arthropods’ exoskeleton.

Some additional observations on the Nostoc-Cricotopus mutualism were pu-

lished by TODD (1971), while recording new algae from Colorado, U.S.A..

.4 DISPERSAL

The mud dauber wasp, Sceliphron caementarium, and the cabbage butterfly,

Heris protodice, were shown by S1DES (1970, 1971) to transport viable algae

and protozoa). The algal cultures obtained were similar to those found by

ormer investigators. It was concluded (SIDES, l. c.) that Sceliphron may be a

elatively important carrier of algae and protozoa, but that the cabbage butterfly

is only a minor vector. SOLON and STEWART (1972) reported that carnivorous

nsects such as dragonflies (Odonata), preying on other insects which live near

water, may also transport viable algal cells, this dispersai being merely acciden¬

tai or incidental.

Source : MNHN. Paris

240

U. GERSON

ANDERSON, LEIDHAL and BRASHIER (1971) reported on the presence of

viable algae in the anterior and posterior gut parts of the chironomid fly Tendi-

pes plumosa. Presence of algae in the latter part suggests that they may also

be dispersed by this midge.

Dissémination of viable algal propagules into the tissues of another plant by

chironomid larvae was postulated by BERG (1950). That author found small

larvae of Cricotopus flavipes excavating longitudinal mines in stems of the ma-

crophyte Potamogeton. Viable algae, identified as Nostoc, Anabaena and others,

were also found in the excavations. BERG (/. c.) thought it possible that the lar¬

vae had introduced the original algal propagules into the mines, where the algae

were growing as rapidly as they were being eaten by the larvae.

6. 4 WATER BLOOMS AND TOXINS

O’ BRIEN and DE NOYELLES (1972) reported on a pH-related mortality

factor which affected cladocerans in nutrient-enriched ponds maintaining very

high levels of primary production. Ryther’s 1954 results were reinterpreted by

O’ BRIEN and DE NOYELLES (1972) as having been caused, in part, by a simi-

lar elevated pH mortality factor.

6. 5 THE BIOLOGICAL CONTROL OF MOSQUITOES BY ALGAE

A signifie an t contribution in this area was made by AMONKAR (1969) in his

Ph. D. thesis (later summarized by REEVES 1970). Amonkar isolated several

algal cultures from Southern California freshwater bodies in which natural con-

trol of mosquito larvae was apparently taking place. Cultures of Cladophora glo-

merata (denoted as culture AL-001), Schizothrix friesii (AL-003), Chara fragilis

(AL-004), Chlorella ellipsoidea (AL-005) and Chara elegans (AL-010, AL-011,

AL-012) exhibited marked larvicidal properties. The effects of these algae were

assayed by their stérile, spent growth media whose usually alkaline reaction did

not, by itself, affect the larvae. This indicates that the larvicidal activity is due to

toxic substances which the algae release into the surrounding water (or culture

medium).

The spent algal media (and purified concentrations prepared thereof) delayed

mosquito egg hatching, reduced larval weights and, most significantly, proved to

be highly larvicidal. AL-001 and AL-003 were the more toxic. Histopathological

studies on mosquito larvae treated with the chromatographically-purified AL

001 toxic fraction revealed destructive effects on the épithélial lining of the

alimentary canal. This damage disrupted normal food passage through the ali-

mentary canal, causing leakage of gut contents into the haemocoel.

The toxin secreted by AL-001 is a heat-stable, non-dialyzable compound,

whose ultraviolet and infra-red spectroscopic patterns suggest that it is an unsa-

turated organic substance with a nitrile group as well as terminal methylenes.

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

241

The active fraction from AL-003 appears to be a similar although different com-

pound. The toxic sécrétions of AL-004, 010, 011 and 012 are identical, having

sulfoxide and terminal methylene groups.

These natural toxins appear to be quite spécifie mosquito larvicides, as no

adverse effects on other organisms - including water insects - could be detected

in the original freshwater bodies. The findings of AMONKAR (1969) are there-

fore of wide practical importance, a point which he emphasized. He also revie-

wed most of the literature on algae which inhibit or kill mosquito larvae. Delete-

rious aspects of the use of algae to control mosquitoes were discussed by YEO

(1972), who suggested that such algae - especially Chara and Cladophora may

cause some aquatic nuisance problems.

The findings about a toxic substance secreted by Cladophora glomerata bring

to mind results reported by 1SHAC and BISHAI (1968) regarding the effect of

this alga on Biomphalaria boissyi, the snail host of Schistosoma mansoni, the

causal agent of bilharziasis. Growth of C. glomerata on the shells of the snails

reduced the latters’ fecundity as well as egg fertility and hatchability. ISHAC

and BISHAI (/. c.) attributed these effects to presence of acrylic acid

CH^=CH— COOH) in Cladophora. The toxic compound isolated by AMON-

KAR (1969) from C. glomerata could thus hâve been a polymerization product

of acrylic acid, whose carboxyl group was replaced by a cyanide to form a

nitrile.

6. 8 INDIRECT EFFECTS OF HYDROLYZED SEAWEED

HAMSTEAD (1970) conducted two experiments with the hydrolyzed sea-

weed product Sea-Born intended to control the two-spotted spider mite,

Tetranychus urticae. In the first experiment a substancial decrease took place in

che pest populations following applications of the seaweed hydrolysate and

^eleases of a predaceous mite, as compared to predator releases combined with

water sprays. In the second, more detailed experiment, no discernible décliné

in pest populations followed applications of Sea-BornW by itself.

7. 1 COMMUN1TIES ON SEAWEED AND ON FRESHWATER ALGAE

Compétition within an animal community living on algal belts in the Baltic

Sea off the Swedish coast was studied by JANSSON (1969). She found that

early in july the belts are colonized by juvéniles of the isopods Idotea baltica and

I. chelipes which feed on the algae and on sessile diatoms living thereon. Their

feeding causes various compétition patterns to occur among the isopods as well

as among the rotifers and ciliates which live in the same community.

WIEGERT and MITCHELL (1973) studied the effect of algal mat stability on

adult brine fly ( Paracoenia turbida) parasitization by the water mite Partnuniella

thermalis. The fly lives in and on mucilaginous mats formed by blue-green

algae and bacteria in hot springs at Yellowstone National Park. Paracoenia has a

Source :MNHN. Paris

242

U. GERS ON

short life cycle (14 days at 35 C), and its voracious larvae can rapidly destroy

suitable mats. The mite, on the other hand, has a slower life cycle, consequently

parasitizing its host-flies only in relatively stable mats. The mite-fly intersect

(i. e., percent of flies parasitized and size of mite load on these flies) may there-

fore be used as a sensitive measure of mat stability.

7. 3 COMPETITION FOR SETTLING SITES

LIPKIN and SAFRIEL (1971), in their studies on the zonation of Mediterra-

nean rocky shores at Mikhmoret, Israël, found that populations of the barnacle

Chthamalusstellatus may be suppressed by algae in the mid-midlittoral intertidal

zone. Individual barnacles may, however, survive under the algal cover.

7. 4 COMMUNITIES AFFECTED BY TECHNOLOGICAL CHANGES

Algal growth on flooded trees in the man-made Volta Lake (Ghana) supports

a great abundance of the borrowing mayfly Povilla adusta (PETR 1971). The

insects are heavily exploited by commercial fish. A man-made alga-insect-fish

food chain, of considérable importance in the convertion of algae into animal

protein, has thus evolved as a resuit of technological changes.

The pollution-associated disruption of invertebrate communities which live

in kelp forest holdfasts in the North Sea was described by JONES (1973). He

noted that many species (including numerous arthropods) hâve disappeared from

these communities. Mechanical harvesting (raking) of Irish moss (Chondrus

crispus ) near Prince Edward Island damages many «moss»-associated lobsters,

reducing their landed value by about 7% (SCARRATT 1973).

The réduction of herbivorous crustaceans by insecticide treatments of fresh-

water ponds was observed by HURLBERT, MULLA and WILLSON (1972) to be

foliowed by phytoplankton increases to bloom dimensions.

7. 5 SOME GEOLOGICAL ASPECTS OF ALGA-ARTHROPOD ASSOCIA¬

TIONS.

Some copepods produce diatom-containing fecal pellets which are enclosed

within a membrane (SCHRADER 1971). These pellets form deep-sea diatom

sédiments occuring down to 4000 m off the coast of Portugal. The diatoms

would not hâve sunk by themselves, without being enclosed by the membrane,

as they would hâve been completely dissolved before reaching such depths. This

illustrâtes the rôle of copepod-produced fecal pellets in the sédimentation of

pelagic diatoms.

Source : MNHN. Pari.

ASSOCIATIONS OF ALGAE WITH ARTHROPODS

243

8. 2 EFFECT OF INSECTICIDES ON ALGAE

Insecticide concentration in algae, the differential reaction of diverse algal

species to insecticides, and effect of the résultant variable mortality (or inhibi¬

tion) on aquatic ecosystems and food chains were discussed in some recent

papers.

COX (1970) found that the level of DDT and some of its métabolites was tri-

pied in phytoplankton samples collected off the Californian coast from 1955 to

1969. Several freshwater algae, such as Anacystis nidulans, Scenedesmus obli¬

quas and Euglena gracilis, concentrated DDT 850, 630 and 100 fold, respecti-

vely, from their media (GREGORY, REED and PRIESTER 1969). The organo-

phosphorus insecticide parathion was concentrated by these algae about 50-70

times. The ability of algae to retain and concentrate insecticides may hâve im¬

plications for control of pests which live in and feed on these plants. BURTON

(1973) discussed such possibilities upon finding huge numbers of black fly (Si-

mulium) larvae feeding exclusively on Oedegonium filaments in Ghana.

EGLOFF and PARTRIDGE (1972) showed thatChlamydomonas reinhardtii

was not affected by concentrations of 100-1000 ppb of DDT. These authors

speculated that such relatively-resistant species might displace less tolérant ones

in polluted situations and thereby reduce or alter species composition in fresh¬

water bodies exposed to insecticides.

This idea was experimentally explored by MOSSER, FISHER and WURSTER

(1972). DDT or polychlorinated biphenyls were added to mixed cultures of the

insecticide-susceptible diatom Thalassiosira pseudonana and the résistant greén

alga Dunaliella tertiolecta. In mixed control cultures the diatom grew faster and

became dominant. But the dominance of Thalassiosira diminished on introdu-

cing the Chemicals, even at concentrations that had no apparent effect when

added to pure algal cultures. MOSSER et al. (/. c.) concluded that such stable

pollulants «could profoundly affect the health, distribution and abundance of

many animal populations higher in the food web». A more moderate opinion as

to the effect of DDT on oceanic life was expressed by JUKES (1974).

The interactions of pesticides and algae were discussed within the context of

pesticide-microorganism reviews by PFISTER (1972) and by WARE and ROAN

(1970).

Several more technical papers on this subject were recently published in the

Bulletin of Environmental Contamination and Toxicology but they are outside

the scope of the présent review.

9. 1 THE SCARCITY OF SYMBIOSIS

Doubts about the validity of the reported wide systematic range of inverte-

brate hosts for algae were expressed by TAYLOR (1973). He argued that most

animais which participate in symbiotic associations with algae are characterized

by a relatively low level of intercellular co-ordination. The introduction of alien

244

U. GERS ON

cells into tissues of such invertebrates would do little to disrupt the animais’

underlying organization. Further, these animais hâve low or non-existent immu-

nological barriers. Cohabitation with algal cells thus causes little cellular difficul-

ties for the host. TAYLOR (l. c.) also pointed out that the majority of symbiotic

hosts are carnivores, hence less likely to be capable of digesting their associated

algae. The establishment of symbiosis with herbivores probably dépends upon

algal résistance to digestion as well as increased host susceptibility.

These remarks go a long way towards explaining the scarcity of symbiosis

between arthropods and algae. They cannot however apply to associations invol-

ving bacteria, yeasts and fungi, as these organisms often occur as symbiotes of

insects, animais with highly developed cellular co-ordination. One thus feels

that algae are rather different from other microorganisms in their relative suitabi-

lity for symbiosis, as already suggested by DROOP (in main reference list).

TAYLOR (1973), as noted, pointed out that most invertebrates which host

algae are carnivorous. It is therefore of interest that the only arthropods hitherto

reported to hâve algal symbiotes are damsel Aies, which are predaceous insects. It

is of further interest that the symbiotic algae studied by WILLEY (1972) enter

their host via its rectum, and those reported by SELVARAJ and JOB (in main

reference list) live in the caudal lamellae of their host, near the main trachéal

branches. The symbiotic algae are not very likely to be much affected by their

hosts’ digestive System in either case.

BIBLIOGRAPHY

AMONKAR, S. V., 1969 — Fresh water algae and their métabolites as a means of biological

control of mosquitoes. Ph. D. thesis, University of California, Riverside.

ANDERSON, R. G., LEIDAHL, G., and BRASHIER, C. K., 1971 — Viable algae in chiro-

nomid larvae.J. Phycol. 7 (Supl.) : 10.

ARNOLD, D. E., 1971 — Ingestion, assimilation, survival and reproduction by Daphnia

pulex fed seven species of blue-green algae. Limnol. Oceanogr. 16 : 906-920.

BARNARD, J. L., 1972 — The marine fauna of New Zealand : algae-living littoral Gammari-

dea (Crustacea : Amphipoda ). New Zealand Dept. Sc. Indust. Res. Bull 210.

BATTAGLIA, B., 1970 — Cultivation of marine copepods for genetic and evolutionary re-

search. Helgolander Wissen. Meeresunt. 20 : 385-392.

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249

VAUCHERIA ON «CORAL» (LITHOTHAMNION) SAND

J J>. CULLINANE*

SUMMARY. — Species of the genus Vaucheria usually grow in or on very damp soil or mud

or even submerged in either fresh or sait water. In the Connemara district of County Galway

in the west of Ireland, Vaucheria was found growing on coral sand ( Lithothamnion calca-

reum). This very coarse and brittle substrate contrasts completely with the more usual type

of habitat. Four species hâve been found, namely : Vaucheria geminata (Vauch.) de Candol-

le, V. sessilis (Vauch.) de Candolle, V. de Baryana Woronin and V. pachyderma Walz. The

latter two species hâve not been previously recorded from Ireland.

RÉSUMÉ. - Les espèces du genre Vaucheria poussent habituellement sur ou dans des sols

humides, boueux ou même recouverts par des eaux douces ou salées. Dans le district de

Connemara dans le comté de Galway, à l’ouest de l’Irlande, des Vaucheria ont été récoltées

sur des sables à Lithothamnion calcareum. Ce type de substrat différé totalement de 1 habi¬

tat type usuel de cette algue. Quatre espèces ont été récoltées : Vaucheria geminata (Vauch.)

de Candolle, V. sessilis (Vauch.) de Candolle, V. de Baryana Woronin et V. pachyderma

Walz. Les deux dernières espèces sont signalées pour la première fois en Irlande.

I. INTRODUCTION

The Vaucheria was first noticed on the coral sand on march 3, 1969 at Ard-

more on the Carna side of Killkieran bay and later on june 23 at Carraroe. In

march 1970, it was found on a third coral strand at Streamstown bay, north of

Clifden. In april 1970 it was found on another coral strand on the western side

of Gorumna island. The habitat was unique. At Ardmore, Carraroe and Mannin

bay drainage from the fields above créâtes a channel in the coral sand and the

Vaucheria grows in this. Heavy rains fill the channel so that the Vaucheria is

then submerged in fresh water. Either the fresh water drainage or the high tide

can cause the sand in the channel to collapse and cover the Vaucheria but within

a few days it grows up through the sand and forms a new mat on the surface. At

both Streamstown bay and Gorumna island, the habitat was essentially the

same but the Vaucheria grew in very small amounts on large clean coral directly

underneath a trickle of water which seeped from a rock.

The four species recorded from this type of habitat are not included in the

Check-lists of British Marine Algae (PARKE and DIXON 1968). However, where

they were growing on the coral sand they were subjected to submersion by the

high tide. Examination of specimens following or during a high tide showed that

* Botany Department, University College, Cork, Ireland.

Rev. Algol., N. S., 1976, XI, 3-4 : 249-259.

Source : MNHN, Paris

250

J. P. CULLINANE

the Vaucheria was plasmolysed and it then usually became extremely fertile

within a few days. Material of V. geminata collected from coral strands at both

Ardmore and Carraroe was compared with material of the same species from the

Cambridge Culture Collection. The latter was plasmolysed by 40% saltwater

whereas the coral strand material was only slightly plasmolysed 50% saltwater.

Aplanospores and akinetes from the coral strand material germinated in fresh

water, half seawater and in full seawater but survived for far longer period in half

seawater. Although growing in very saline conditions the Vaucheria on the coral

does dépend on the fresh water drainage as it does not grow during the dry

summer months when even the channels are not présent. The Vaucheria reappears

early in october and remains throughout the winter months. However, its

occurence dépends more on rainfall than on the actual seasons since, following

about four days of very heavy rain during june 1969 and july 1970, the Vauche¬

ria was found but it soon disappeared when the channel again dried out.

None of the specimens growing on the coral were impregnated with calcium

as were samples collected by CHRISTENSEN (1969) from the rapids of a brook

and described by him as «small cushion-like masses so heavily encrusted with

lime that they felt hard and stone-like when collected».

II. DESCRIPTION OF THE SPECIES

a. VAUCHERIA DE BARYANA WORONIN. (fig. 1-15).

WORONIN (1880) in naming this species after DE BARY States that he

found it in small fast running rivers and in the well of a spring. VAUCHER

(1803) States that it grows in dull green masses in ditches with stagnant water.

CHRISTENSEN (1969) collected this species on soil near running water and

actually in water and in places flooded by water now and then. These and other

records of this species, GOETZ (1897), DANGEARD (1939), RIETH (1965)

contrasts with the maritime conditions on the hard brittle coral sand.

The fïrst specimen collected at Ardmore coral strand formed a thick mat

about six inches in diameter and dark green in colour with pale edges. The mat

was divided into four parts and these were kept in separate crude cultures and

each became fertile within four days. The reproductive organs and filament

widths matched those of V. de Baryana as described and illustrated by WORO¬

NIN (1880), VENKATARAMAN (1961), RIETH (1965) and CHRISTENSEN

(1969).The oogonia were on stalks 80-100 jUm long and were slightly oval in

shape and measured approximately 40 by 60 nm. The mature oogonium had an

inconspicuous terminal beak (fig. 1-3). The oospores frequently germinate while

still attached (fig. 4). The antheridium was situated between the two oogonia and

was on a long stalk. It had the characteristic flattened anvil shape, which along

with the small filament width readily distinguishes this species from ail others.

The antheridium had two latéral openings, with three on rare occasions. On an

VAUCHERIA ON «CORAL» SAND

251

average it measured 20 nm high by 35 nm wide.

Twenty-seven days after collection the plant died off but filaments reappea-

red after twelve days and were fertile within another twelve days. The reproduc¬

tive organs were similar but the oogonia were on shorter stalks and in some cases

were almost sessile so that they were at a lower level than the antheridium (fig.

5-7). This variation is also illustrated by VENKATARAMAN (1961, fig. 68 ) and

by CHR1STENSEN (1969, fig. 6848a). By the time the culture was eight weeks

old, the oogonia were almost ail completely sessile with only one to each anthe¬

ridium, a feature which was consistent in one sample described by CHRISTEN-

SEN. In the final stages of the culture, twelve weeks after collection, ail the oo¬

gonia were completely sessile with only one to each antheridium. The culture

was then feebly producing its third crop of reproductive organs. V. de Baryana

was collected at Ardmore on eight different occasions and once from Mannin

bay. Each collection from Ardmore was kept in culture. Nearly ail cultures survi-

ved through three stages of reproduction which regularly alternated with stérile

periods. The pattern in each case was similar, as the culture aged the oogonia be-

came sessile and reduced to one per antheridium. In three to four months old

cultures, the antheridia were no longer terminal but were on very short latéral

branches which originated from the same part of the filament as did the short

oogonial branches (cf. fig. 8). This variation is similar to that illustrated by

RIETH (1965, p. 504, fig. c). This «unhealthy» State was also common in a sam¬

ple at the time of its collection from Mannin bay. This sample was not in good

condition as it looked brown in colour and was almost completely devoid of

chlorophyll at the time of collection. In some samples collected at Ardmore

which formed only loose threads, the oogonia présent at the time of the collec¬

tion were frequently almost sessile. Prolifération was only observed three times

(fig. 9). Branches with deformed antheridia and oogonia occured in the latter

stages of culturing but were never frequent. Inthese cases the shape of the an¬

theridia and oogonia were recognisable but they were not eut off (fig. 10-14).

Although the reproductive organs changed with the âge of the culture they were

always recognisable as those of V. de Baryana. This was especially true of the an¬

theridium which only altered slightly in shape (fig. 15). The antheridial stalk was

never hooked as illustrated by RIETH and CHRISTENSEN and mentioned by

VENKATARAMAN. No other form of reproduction was ever observed in this

species. The width of the filaments always remained within the original limits of

20-50 iim.As stated by VAUCHER (1803), these dimensions are «very much

finer than those of V. geminata and ail the dimensions of its fruiting organs are

about half of those found in V. geminata».

b. VAUCHERIA GEMINATA (VAUCH.) DE CANDOLLE. (fig. 16-23).

In may 1969 Vaucheria was collected from a second location at Ardmore

coral strand. The species was identified as V. de Baryana by the reproductive

organs présent and the filament width (18-48 /im). However, a large portion of

the filaments varied in width from 40-110 fim. After three weeks in culture these

252

J. P. CULLINANE

filaments became fertile and were identified as V. geminata. The V. de Baryana,

which was extremely fertile at the time of collection and even had numerous

oospores germinating in situ, died off after two weeks and did not recover. These

two species were found intermingled in at least seven different samples from

Ardmore and in one sample from Mannin Bay. CHRISTENSEN (1969) also re¬

cords V. de Baryana growing mixed with several other species but does not in-

clude V. geminata among them. At Carraroe V. geminata was frequently found

growing on the coral sand but it was never accompanied by any other species.

The V. geminata was identified from the descriptions and illustrations of

VENKATARAMAN (1961), and CHRISTENSEN (1969). The cylindrical circi-

nate antheridium was terminal, on a short stalk and opened by a single large ter¬

minal pore. It was situated between two oogonia which were on short latéral

branches. The oogonia were fiat or concave on one side and had a small beak

facing the antheridium. In one collection the darker green centre of the material

was more fertile than the paler edges. The oogonia were on longer branches but

were smaller in size and measured from 65-80 nm in width in the darker central

parts, whereas those on the shorter branches in the paler portions measured from

90-120 /im in width. V. geminata frequently survived in culture for over three

months. A second and third stage of sexual reproduction was observed but the

reproductive organs did not alter much, except for a tendency to reduce the

number of oogonia to one per antheridium in a few cases and a tendency to-

wards more sessile oogonia. The fruiting organs did not alter with âge as much as

in V. de Baryana and neither was the alternation of fertile and non fertile phases

as pronounced. Prolifération of branches showing as many as five pairs of sessile

oogonia was observed in cultures after three months but was never abundant. It

was, however, very common in one collection from Carraroe in which Vauche-

ria was extremely fertile as a resuit of having been covered by the sand, follo-

wing submersion by a high tide (fig. 16, 17). In rare cases in old cultures the

antheridial branches were extremely short and swollen into broad triangular

shapes as much as 210 flm wide but oogonia were never observed in such cases

(% 18).

After nearly four months in culture the filaments had not altered their width

beyond the original 40-110 /im but they eventually broke up into short thick

walled irregular pièces or akinates. These were very common in old cultures of

this species. Aplanospores were observed at various stages of culturing. They

were oval in shape and measured 68-119 by 119-153 fim.

c. VAUCHERIA SESSILIS (VAUCH.) DE CANDOLLE. (fig. 24-29).

On june 26 1969 it was noticed that at the entrance to Ardmore strand low

down on the shore, within fourteen feet of the then high tide, the coral sand was

coloured red by the iron seepage. Although no Vaucheria was visible a sample of

the sand was kept in the laboratory and after a few days it revealed two species :

V. geminata and V. sessilis. These two species could only be distinguished by

VAUCHERIA ON «CORAL» SAND

253

their fruiting bodies as the filaments of the former varied from 35-95 /im in

width and those of the latter varied from 30-92 pm.

The V. sessilis agreed with the description given by CHRISTENSEN in that

«the species varied a good deal with regard to the direction of the beak of the

oogonium and the width of the filaments, and the tendency to form only one

oogonium near each antheridium». The cyündrical antheridium is either circina-

te or rarely straight, erect or coiled downwards and it opens by a single large ter¬

minal opening. The antheridium is either near a single oogonium or situated

between two oogonia. The oogonia are either sessile or on very short pedicels

and hâve a short beak which varies in position but usually faces the antheridium.

V. sessilis was collected from the red tinged coral sand at this location on

four other occasions. In culture the fruiting bodies remained continuously for up

to two months without variation, other than already described and without al-

cernating fruiting periods.

As was the case with the previous species the occurence on the hard brittle

coral sand close to the high tide level contrasts with its more usual habitat.

CHRISTENSEN for example records it from swiftly running water, on soil at a

vatercourse, and from stagnant water. As was the case with the samples collec-

ed by CHRISTENSEN, the coral sand samples, with the exception of the first,

vere always fertile at the time of collection.

. VAUCHERIA PACHYDERMA WALZ. (fig. 30-34).

A sample of sand from Ardmore taken in december 1969 was placed in cultu-

e and shown to contain V. de Baryana. Some wider filaments ranging from 40

o 95 pm in width, became fertile after three weeks and matched the descrip-

ion and drawings of V. pachyderma as given by VENKATARAMAN (1961)

md CHRISTENSEN (1969). DANGEARD (1939) gives the filament width

or this species as being 35-45 pm whereas VENKATARAMAN gives it as 40-

123 pm. The latter measurements are more in keeping with those of the coral

.and samples. This species is characterised by the extremely thick wall of the

oogonium which measured as much as 7 pm in thickness and consists of 5-7

ayers. The oogonia varied very much in shape and were sometimes almost sphe-

ical and in other cases very flattened and paralleled to the filament. They varied

n width from 95-180 pm and in height from 90-140 pm. They were usually ses-

ile or rarely slightly pedicillate. The antheridia matured much earlier than the

jogonia and they resembled those of V. sessilis in that they were cylindrical,

talked and frequently circinate and were situated next to the oogonium but

here was always only one oogonium to each antheridium. The antheridium

îsually grew downwards. The prominent beak on the oogonium was situated

nore on the side and often pointed downwards. Collections made in april 1970

rom this location contained only V. pachyderma.

One collection was made at Streamstown bay. Only a minute amount of

254

J. P. CULLINANE

Vaucheria was présent and it never became fertile. Similarly a collection from a

coral strand on the western side of Gorumna island never became fertile. How-

ever, in both of these cases the filaments were too wide to belong to the species

V. de Baryana.

e. INTERMINGLING OF SPECIES.

As appears to be typical of Vaucheria in general the various species found

growing on the coral sand were frequently intermingled with each other as is

summarised in the table. At Carraroe however, V. geminata was the only species

ever recorded. Material collected at Ardmore strand, in october 1969, was kept

in crude culture and became fertile after two weeks and was V. geminata, two

weeks later however the fertile filaments were V. sessilis. Some very fine fila¬

ments présent in the material from the time of collection only became fertile

after three months and this species was then identified as V. de Baryana. This

was the only collection to contain three species and it is of interest that the

V. de Baryana did not become fertile untü after the death of the other twc

species. By the time it did become fertile the V. de Baryana was old and unheal

thy in appearance and the reproductive organs présent were those typical of old

cultures as described earlier and illustrated in fig. 8.

Table 1 : locations of species (+intermingling species)

Ardmore

Ardmore Carraroe

Mannin bay

Gorumna isl.

Entrance

offshore

north-eastern

side

V. de Baryana

V. geminata V. geminata

V. geminata

V. pachyderma

V. de Baryana

V. geminata

V. de Baryana

V. geminata

V. sessilis

V. de Baryana

V. pachyderma

V. de Baryana

V. geminata

V. sessilis

Grid Référencés, according to Irish Ordonance Survey Maps, sheet 10 (scale 1/2

inch to a mile) :

Carraroe : L. 91 22; Ardmore : L. 82 29; Mannin bay : L. 63 48; Streamstown

bay : L. 58 54; Gorumna Island : L. 85 23.

VAUCHERIA ON «CORAL» SAND

255

acknowledgments

I wish to thank Professor M. de Valera, University College, Galway, for directing this

work and for her kindness and assistance at ail times during the préparation of this pa-

per.

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VAUCHERIA ON «CORAL» S AND

257

Source : MNHN, Paris

258

J. P. CULLINANE

Source : MNHN, Paris

VAUCHERIA ON «CORAL» SAND

259

Source : MNHN, Paris

261

THE STRUCTURE

OF OSCILLATORIA LIMOSA AG. (CYANOPHYCEA)

AND THE FORMATION

OF HORMOGONIA AND NECRIDIA

A STUDY USING THE LIGHT MICROSCOPE, THE SCANNING AND

TRANSMISSION ELECTRON MICROSCOPES

E. FJERDINGSTAD, Bo HOLMA, and Ejnar J. FJERDINGSTAD *

SUMMARY. - The structure and reproduction of the biue-green alga Oscillatoria limosa Ag.

as seen with the light microscope, the scanning and transmission électron microscopes. The

results emphasize the necessity of a higher resolving power than it is possible to obtain with

conventional techniques using light microscopy for classifying the blue-green algae according

to morphological characteristics, e. g. the formation of hormonia by means of necridia has

given rise to erroneous establishment of Oscillatoria refringens and O. lauterbomii fa. calyp-

tra.

RÉSUMÉ. - L’observation de la structure et de la reproduction de Oscillatoria limosa Ag.

au microscope photonique ainsi qu’aux microscopes électroniques à transmission et à

balayage soulignent la nécessité d’utiliser de fortes résolutions supérieures à celles du micro¬

scope photonique pour réussir à distinguer les Cyanophycees d’apres leurs caractères mor¬

phologiques, comme le prouve la création erronée d'Oscillatoria refringens et O. lauterbor-

nii fa. calyptra.

I. INTRODUCTION

The appearance of the scanning électron microscope (SEM), which has a

higher resolving power (depth of focus about 300 times better than that of the

light microscope, cf. GRAY), and in which the image, unlike that of the light

microscope, is three-dimensional, has made it possible to study more closely the

taxonomically highly significant external structure of the microorganisms. Thus

the scanning microscope has been used successfully for the study of Diatoms and

Foraminifera, (cf. BARLETT 1967; BE 1968; BENS & DREWS 1967; HAY &

* Institute of Hygiene and Institute of Zoology, University of Copenhagen.

Rev. Algol., N. S., 1976, XI, 3-4 : 261-272.

Source : MNHN, Paris

262

E. FJERDINGSTAD

SUNDBURG 1967; HONJO & BERGGREEN 1967), of soil microorganisms by

GRAY (1967), of fossil diatoms by MILLER (1969), and of desmids by LYON

(1969). Cyanophyceae as Merismopediaglauca, Anacystis montana, and Oscilla-

toria formosa hâve been studied with the scanning électron microscope by

ECHLIN (1968), but the figures given by this author provide no useful informa¬

tion on the surface structure since the organisms hâve been covered by the élec¬

tron dense layer - a phenomenon frequently observed by the authors of the

présent article, for instance in the case of Spirulina major, Oscillatoria chalybea,

and Phormidium foveolarum etc. (cf. fig. 1 a-b). Incidentally, BRINGMANN

(1950: 557) and METZNER (1955 : 53) State that trichomes of Cyanophyceae

in the transmission électron microscope (TEM) are frequently seen to be sur-

rounded by an outer électron dense layer, even at high électron potentials. It is

understandable, therefore, that the scanning électron microscope has not as yet

been as useful in the study of the morphology and taxonomy of Cyanophyceae

as might hâve been expected. That it is nevertheless possible by means of this

technique to disclose structures which cannot be seen with the light microscope

will appear from the micrographs of Oscillatoria limosa Ag. in the présent article.

The scanning électron microscope will thus be a valuable supplément to the

transmission électron microscope and the light microscope in the study of blue-

green algae.

II. MATERIAL AND METHODS

The material studied in the présent work was collected two to three years ago

from various localities in Denmark. Duplicate samples were collected, one

sample was at once fixed in 4% formaldéhyde solution, while living cells of the

other sample were viewed with the light microscope.

For use with the scanning électron microscope material stored in formaldé¬

hyde was used. It was washed in distilled water for 30 minutes, transfered to

60% alcohol for 30 minutes, and to absolute alcohol for 30 minutes. After this,

a drop of the concentrated sample was spread as a thin uniform layer on a cir-

cular cover glass, 9 mm in diameter, and dried gently. The cover glass with the

layer of algae upwards was then secured to a stub with little dab of synthetic

glue. Before being viewed with the scanning électron microscope the organisms

were coated with a conductive substance (gold) in a vacuum evaporator.

The scanning électron microscope studies were made in collaboration with

Analytical A. B., Sollentuna, Sweden.

It is the présent authors’ expérience that Cyanophycea material which has

been kept for considérable time in formaldéhyde gives better results (no shrin-

kage) than material which has been fixed for a short time only.

For use with the transmission électron microscope material which had been

kept in formaldéhyde was washed in distilled water for twelve hours, fixed in

buffered 2% osmium tetroxide solution for one hour and embedded in Epon.

Sections were eut on a LKB Ultrotome, and the sections were picked up on

STRUCTURE OF OSCILLATORIA LIMOSA

263

carbon stabilized Parlodion films, poststained on the grid with zinc uranyl acéta¬

te + lead citrate and viewed with a Siemens Elmiskop I b. and Cari Zeiss E M 9.

The microscope was operated at 40 kV.

This part of the study was made in the Institute of General Zoology.

III. OBSERVATIONS

a. LIGHT MICROSCOPY

GEITLER (1932) describes Osciïlatoria limosa Ag. as having more or less

straight trichomes, usually forminga dark blue-green, brownish or olive-green mass.

Trichomes are not, or only slightly, constricted at cross walls, mostly 13-16 pm

in diameter, cells are 2-5 /Jm long, end cells are fiat, rounded with thickened

membrane - occasionally with sheath formation.

In a recent paper FJERDINGSTAD (1971) has accounted for the résulte of

examinations of a very great number of trichomes of Osciïlatoria limosa deriving

in part from material collected by the author in Denmark, in part from different

exsiccate materials, and in part from herbarium materials stored in the Botanical

Muséum of the Copenhagen University. With regard to the morphological featu-

res it appears from FJERDINGSTAD’s examinations that in most of the tricho¬

mes the outer membrane of the end cell is not thickened. A slight atténuation at

the tips was observed in about 50% of the samples, a slight constriction at the

cross walls in about 36%, and granules at the cross walls in about 47%. The pré¬

sence of a firm sheath was observed, however, only infrequently. Most frequen-

tly there is a thin, hyaline layer along the outer walls of the trichome correspon-

ding to the thin, mucous sheath occuring in some species of the genus Phormi-

dium.

As regards the dimensions of the organisms in the materials dealt with here

the diameters of trichomes of O. limosa from Ketting brook (fig. 2) were :

minimum 12 /im, maximum 19 pm mean, and dispersion 14.5 ± 0.9(8) pm,

from a spring in Askemose forest (fig. 5-7) the figures were 10 pm, 16 pm and

12.4(5) ± 0.8(4) pm respectively, and from Lille Holmehave brook 12 pm,

19 pm and 14.5 ± 0.9(8) pm.

Hormogonia are developed through the formation of necridia (fig. 2b, 2d).

The septa of the neighbouring cells on both sides of a necridium assume convex

shape whereby the protoplasm of the necridium is compressed, and it becomes

biconcave. Now the only connection between the neighbouring cells is the cir¬

culât border of each intervening septum, cp. also KOHL (1903). Laterally a

necridium often bulges slightly so as to produce a curve in the otherwise linear

outline of the trichome. When the séparation between the cells is completed,

the necridium dies. Necridia are frequent in the material of O. limosa studied in

the présent work.

A specimen of O. limosa with necridia has been described by GARDNER

264

E. FJERDINGSTAD

(1927), erroneously, as an independent species : O. refringens - although GARD-

NER herself mentions that some trichomes, especially young ones, lack such

«réfringent» cells, cp. also FJERDINGSTAD (1971).

When the séparation at the necridium is completed, remnants of the necridial

cell wall may sometimes be found on the outside of the end cell (fîg. 2d). Due to

erroneous interprétation of this phenomenon a variety ofO. lauterbornii Schmi-

dle, viz. var. calyptra, has been established. According to the figure given by

CLAUS (1955) it is not a case of actual calyptra formation, but obviously

remnants of a (necridial) cell membrane which has been interpreted as a caly¬

ptra. Thus var. calyptra Claus should not be considered an indépendant taxon.

b. SCANNING ELECTRON MICROSCOPY

With lower as well as higher magnification blue-green algae often appear in

the scanning électron microscope to be covered with an outer, électron dense

layer which appears as a uniform coating (fig. 1 a-b).

As mentioned in the above, when viewed with the light microscope O. limosa

showed a slight constriction at the cross walls in about 36% of the material.

Viewed with the scanning électron microscope this constriction appears very

clearly in specimens in which there is no électron dense layer (fig. 3-4). It

appears from fig. 5 that constrictions at the cross walls do not always occur.

There are thus two types of O. limosa, but no taxonomie significance should be

asenbed to this morphological différence, since FRITSCH (1953) in Phormi-

dtum strata found trichomes with constrictions and trichomes without constric-

tions, while FJERDINGSTAD (1969) mentions that trichomes of Anabaena

vanabihs may be found with constrictions in one half of the trichomes and none

in the other half. The same may be observed in O. limosa, cp. FJERDINGSTAD

In culture experiments with a Lyngbya species PEARSON & KINGSBURY

(1966 : 198) hâve shown that the presence or absence of constrictions at the

septa is a characteristic that often varies, even within the same culture vessel.

A S early as 1933 WEBER (1933 : 403) stated that in connection with a species

as Calotnnx Braunu Born. et Flah. no weight can be attached to the presence of

constrictions at the septa, since filaments with and without constrictions occur

Gom la SEM P v'MM "rT J Üt n S £“ l5 °° 0i ^ lb '~ OsciUatorm chalybea (Mertens)

c.om., isEM x 2000, Fig. 2. -OscOataria limosa A. from different localities in Denmark

S erTrwXiÊM x 20 X 0„ b : d ; 87 a 5

walls SEM x 6500- Fit» ^ _ n ■ ® sclllatori ‘* l, mosa mfh constnedons at the cross

n Fig-5. OsciUatoria limosa without constrictions, SEM x 5000- Fia 6

and 0 Ær SEM r 2 “00 D - & fr ° m —", ïïh'dïtase

266

E. FJERDINGSTAD

together. This feature is not mentioned by DARLEY (1968 : 177) in connection

with the species Calothrix parietina Thuret, but following studies of Danish ma-

terials the présent authors are able to confirm that WEBER’s observation applies

also to this species.

Formation of hormogonia occurs as a resuit of the development of necridia,

see in the above. The latéral bulge of the necridium influences either the prece-

ding or the subséquent cell or both so as to cause a protrusion of the middle

part of the new end cell, while at the same time there is a constriction of the

sides which is greater than in the other cells in the trichome. This phenomenon,

which with the light microscope is frequently only just visible, appears very

clearly viewed with the scanning électron microscope (fig. 5).

The outer structure of the trichome surface is another detail which is disclo-

sed by the scanning électron microscope. In O. limosa this surface consists of re

gular, vertical, parallel ribs connecting the septa of the cells and a horizontal

band in the middle of the cell connecting the side walls of the trichome. This

band is probably located at the point where a future cell division might tak<

place (fig. 4).

Preliminary studies hâve shown a corresponding structure in O. animalis Ag.

O. tenuis Ag., and Oscillatoria species from Greenland, and in Phormidiun

autumnale (Ag.) Gom, while the structure of O. rubescens de Candolle differ

from that of the above mentioned in that it is netshaped with irregular, angula

meshes of varying size and appearance (fig. 6). In Symploca muscorum (Ag.

Gom. and in Hydrocoleus the structure corresponds closely to that of O. limosa

In Petalonema, which belongs to the family Scytonemataceae, there are, on th<

other hand, wavy cross ribs which connect the side walls of the trichome and art

more or less parallel to the septa. Whether décisive taxonomie significanct

should be ascribed to the différence in structure will only appear after furthe

studies, but it is a reasonable assumption that it will be of significance, particu

larly to the arrangement of blue-green algae in families, since species of thi

généra Oscillatoria, Phormidium, Symploca, and Hydrocoleus which ail belong

to the family Oscillatoriaceae hâve the same structure. If this holds good, t

species as O. rubescens cannot rightly be referred to the genus Oscillatoria

Plate 2

7. — Oscillatoria limosa showing the photosynthetic apparatus, small osmiophilic gra

nules (ribosomes, lipid granules, polyphosphate granules and incipient cell division, TEM x

6000; Fig. 8. — Oscillatoria limosa, oblique section, TEM x 9000; Fig. 9. — Oscillatorù

limosa, detail of fig. 8, aging cells with many vacuoles and lipid granules, TEM x 19500

Fig. 10. — Oscillatoria limosa showing the clubshaped thickenings at the trichome membra

ne > TEM x 60000; Fig. 11. — Oscillatoria limosa, formation of necridia, TEM x 5800; Fig

12. — Oscillatoria limosa, a later stage of necridium formation with incipient vacuolation

TEM x 16250; Fig. 13. - A young hormogonium of O. limosa (oblique section), TEM x

16250.

STRUCTURE OF OSCILLATORIA LIMOSA

267

Source : MNHN. Paris

268

E. FJERDINGSTAD

c. TRANSMISSION ELECTRON MICROSCOPY

The internai structure was studied by transmission électron microscopy. As it

appears from fig. 7 the morphological form of the photosynthetic apparatus is

lamellar, each lamella consisting of two membranes confïning a space of variable

width. This closed sac, mostly 16.6 to 20 nm broad, has been termed a thyla-

koid. The lamellae are situated next to the membranes at the side walls. Accor-

ding to ECHLIN (1965 : 149) the number and arrangement of the lamellae show

considérable species variation, ranging from tightly packed stacks to a réticulum.

However, variation occurs also according to the âge of the organism (ECHLIN

1964).

Among the thylakoids there are some small osmiophilic bodies which are

globules of lipid, much larger lipid globules, up to 350 x 416.6 nm, are to be

found scattered in the cells (fig. 7).

Ribosomes are small, dense granules occuring in very great numbers in any

cytoplasmic space which is not occupied by other components (LANG 1968 :

Vacuoles appear in some micrographs in great numbers, in others there are

only very few. According to LANG vacuolation becomes more pronounced in

aging cells (fig. 8-9).

NIKLOWITZ & DREWS (1957) mention the presence of a clubshaped

thickened border line at the place where side walls and septa join. HAGEDORN

(1961 . 826), who studied material fixed in potassium permanganate, confirmed

the presence of this clubshaped thickening, but says that it does not represent

any expansion of the membrane. As appears from fig. 10, our micrographs do

not show any clubshaped thickening of this type where longitudinal wall and

cross wall join, but in each cell there are thickenings which do not touch the

cross walls. Their dimensions are 66.6 nm wide by 250 nm long. In the space

between them cell division takes place.

Formation of hormogonia through necridia is seen clearly in fig. 11-13.

IV. DISCUSSION

As mentioned in the above, it was stated as early as 1903 by KOHL that

species of Oscillatoriaceae and Scytonemataceae form hormogonia through

necridia rather than through the septa between living cells. CROW (1925 : 41)

mentions the formation of hormogonia in Lyngbya nigra Ag. through the deve¬

lopment of necridia and writes that «their formation is not preceded by a fissure

of the protoplasm, division is merely a resuit of their formation». In his compré¬

hensive studies of Oscillatoria amoena FUHS (1958 : 523) observed only trans¬

cellular breakage of trichomes, while HALL & CLAUS (1962 : 360) with regard

to the hormogonium formation in Oscillatoria chalybea writes that «there is a

strong indication that the filaments break up by cleavage between the two mem-

STRUCTURE OF OSCILLATORIA LIMOSA

269

branes of the interval». These membranes should thus become the outer mem¬

branes of the wall of the newly formed end cells at the site of the previously

existing cross wall. When HALL & CLAUS further write that «this explanation

would eliminate the theory of FUHS requiring the death of a cell intermediary

between two nascent hormogonia» we do not agréé with these authors as far

as O. limosa is concerned since our micrographs, both in scanning and transmis¬

sion électron microscopy, clearly show the coopération of necridia in the for¬

mation of hormogonia. Nor could LAMONT (1969 : 241) after électron micro¬

scopie examination of a Lyngbya species (identified according to DROUET as

Microcoleus vaginatus (Vauch.) Gom.) find evidence for the hypothesis advanced

by HALL & CLAUS, and he refers quite rightly to the fact that even HALL &

CLAUS’s fig. 1 does not support their claim that a septum of O. chalybea may

split symmetrically to yield an intact cell on either side. HAGEDORN’s (1961 :

827) examinations of O. limosa also show that hormogonium formation takes

place by means of necridia and, unlike HALL & CLAUS, this author writes that

in spite of the fact that cell cross walls consist of three layers, they cannot split,

but form a morphological unit. Even after treatment with enzymes as trypsin,

pepsin, diastase, papain or with acids, bases, or salts it was impossible for HA-

GEDORN to effect a séparation of the layers. As regards Porphyrosiphon Nota-

risii RIS & SINGH (1961 : 65) postulate «that during the hormogonia formation

che cross walls split down the middle and show a peculiar grid-like pattern at the

point of séparation», but the figure (fig. 8) given by the authors does not appear

to confirm this assertion.

In 1962 GIESY (1962) published his observation of the ultra structure in O.

imosa Ag. However, he describes this alga as a filamentous alga with trichomes

ranging from 2 to 6 /im in diameter - «each cell is approximately 2 /im thick». If

the dimensions mentioned do not represent an erratum, this cannot be a spéci¬

men of O. limosa the diameter of which is 10-22 /im, rarely more than 22 /im,

see in the above. It may be mentioned in this connection that the value of élec¬

tron microscopie examinations of organisms using DROUET’s (1968) highly

simplified nomenclature is small if the conventional nomenclature is not given at

the same time.

As mentioned in the above, ECHLIN (1965) has pointed out that the structu¬

re of the lamellar photosynthetic apparatus is species spécifie, and the examina¬

tions made hitherto and being made at présent by the présent authors seem to

confirm this assertion. ECHLIN (1968 : 138) further says «that it may be possi¬

ble, solely on structural grounds, to consider as blue-green algae those organisms

which possess peripheral photosynthetic lamellae while, conversely, the absence

of these structures would indicate that the organisms were bacteria». If bioche-

mical démonstration of the presence of c. phycobilins is added as an indicator of

blue-green algae, «this will begin to delineate the group from other organisms».

CRESPI et al. (1962) write that the action of lysozyme on the different species

differ, some species, for instance O. tenuis and Phormidium luridum , are highly

sensitive to treatment with this enzyme while other species, for instance O. for-

mosa, are not influenced by it. They suggest, therefore, that sensitivity to lyso¬

zyme may be of taxonomie value.

270

E. FJERDINGSTAD

It may be mentioned that in experiments on the influence of diastase and

protease in progress at présent we hâve likewise found the sensitivity of the

individual species to these enzymes to differ greatly.

It would not be realistic to base a révision of the taxonomy of blue-green

algae solely on light microscopie features, even though déterminations of the

range of variability of the width and length of trichome cells with statistical

détermination of mean and dispersion would be highly valuable. The informa¬

tion which may be obtained by means of scanning électron microscopy of the

highly signifïcant outer structure as well as the visualization of the internai

structure provided by transmission électron microscopy, possibly supplemented

by biochemical analyses, should also be utilized.

V. CONCLUSIONS

Structural features of O. limosa Ag. were studied with the light microscope

as well as with the scanning and the transmission électron microscopes.

Hormogonia formation takes place through the development of necridia,

and this has given rise to erroneous establishment of the species O. refringens

Gardner and O. lauterbomii Schmidle/a. calyptra Claus.

The scanning électron microscope shows that the trichome surface in O. limo¬

sa has a peculiar structure which is also observed in other Oscillatoria species,

with the exception of O. rubescens , and in other species belonging to the family

Oscillatoriaceae. This structure differs from the structure in Petalonema of the

family Scytonemataceae. It is reasonable to assume that the outer structure of

the trichome may be utilized for systematical purposes in distinguishing between

the families of blue-green algae. If so, it cannot be correct to refer O. rubescens

to the family Oscillatoriaceae.

As regards the observation by NIKLOWITZ & DREWS (1957) of a clubsha-

ped thickening at the point where the side wall adjoin the cross wall, an observa¬

tion confirmed by HAGEDORN (1961 : 826), we hâve been unable to trace this

phenomenon in our TEM micrographs.

It is finally mentioned that a révision of the taxonomy of Cyanophyceae

should also take into considération the information which scanning électron

microscopy and transmission électron microscopy may provide with regard to

the outer and inner structure of blue-green algae, possibly supplemented with

biochemical tests.

STRUCTURE OF OSCILLATORIA LIMOSA

271

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273

ETUDE COMPARATIVE DES CYCLES DU

LIAGORA TETRASPORIFERA B0RG. ET DU

LIAGORA DISTENTA (MERT.) C. AG. EN CULTURE.

A. COÛTÉ *

RÉSUMÉ. - Alors que le Liagora distenta a un cycle trigénétique hétéromorphe avec un té-

trasporophyte nain bien individualisé, le Liagora tetrasporifera a un cycle digénétique hété¬

romorphe sans tétrasporophyte, les carpotétraspores produisant un nouveau gamétophyte.

Les cycles morphologiques de Liagora distenta et Liagora tetrasporifera ont été étudiés sur

des cultures réalisées en lumière du jour naturelle à la température de 12 C.

SUMMARY. — The morphological cycles of Liagora distenta and L. tetrasporifera, grown in

cultures at 12° C in daylight, are compared. L. distenta shows true alternation of généra¬

tions as do most of the Nemalionales studied with a trigenetic heteromorphous cycle with a

tétrasporophyte. L. tetrasporifera has a digenetic heteromorphous cycle without tetraspo-

'ophyte.

INTRODUCTION

Après les travaux de SVEDELIUS et de KYL1N on a longtemps considéré les

''lémalionales comme haplobiontes, c’est-à-dire comme des individus portant des

arposporocystes, en admettant que les carpospores produisaient directement les

gamétophytes, le zygote subissant la méiose. Dans ces conditions, leur cycle était

digénétique et haplophasique.

Mais les recherches cytologiques de MAGNE ont montré que les carpospores

sont diploïdes et ont laissé supposer l’existence d’un tétrasporophyte, inconnu

jusque-là, libérant des tétraspores haploïdes. De nombreux auteurs ont confirmé

les recherches de MAGNE en mettant en évidence l’existence d’un tétrasporo¬

phyte nain, réduit à un thalle hétérotriche (= «Nématothalle» de CHADE-

Ce travail a constitué la partie principale d’une thèse de doctorat de 3e cycle soutenue

le 19 juin 1972 à l’Université de Paris VI. La bibliographie ne comporte donc pas de réfé¬

rences ultérieures à cette date.

* Laboratoire de Cryptogamie, Muséum National d’Histoire Naturelle, 12 rue de Buffon,

75005 Paris - L. A. n° 257 (C.N.R.S.).

Rev. Algol., N. S., 1976, XI, 3-4 : 273-297.

Source : MNHN, Paris

274

A. COÛTÉ

FAUD) engendré par la germination de la carpospore. Ce fut ainsi le cas de VON

STOSCH avec le Liagora farinosa Lamour. (1965), UMEZAKI avec le Nemalion

vermiculare Suringar (1967) et plus récemment avec le Scinaia japonica Setchell

(1971), FRIES avec le Nemalion multifidum (Weber & Mohr) J. Ag. (1967),

BOILLOT avec le Scinaia furcellata (Turner) Bivona (1968, 1969) et avec 1’ Hel-

minthora divaricata (C. Ag.) J. Ag. (1971), et enfin RAMUS avec le Pseudo-

gloiophloea confusa (Setchell) Levring (1969). VON STOSCH, de plus, avec le

Liagora farinosa, a démontré que la méiose a lieu dans le tétrasporocyste, lors de

la formation des tétraspores, comme chez les autres Floridées.

Toutefois restait posée la question de certaines algues chez lesquelles le con¬

tenu des carposporocystes subit une division en quatre, engendrant ainsi quatre

carpotétraspores. Pour l’ensemble du globe, on en compte actuellement huit qui

se répartissent en trois genres : Liagora tetrasporifera Bôrg. (B0RGESEN,

1927), L. pinnata Harvey (YAMADA, 1938), L. brachyclada (Decaisne) Monta¬

gne (LEVRING, 1941), L. papenfussii Abbott (ABBOTT, 1945), L. harveyana

Zeh (WOMERSLEY, 1965), Helminthocladia hudsoni (C. Ag.) J. Ag. (FELD-

MANN, 1939), H. senegalensis Bodard (BODARD, 1971) et enfin Yamadaella

cenomyce Abbott (ABBOTT,1970).

Le remarquable travail de B0RGESEN sur le Liagora tetrasporifera (1927)

avait conduit à admettre, malgré les points de vue contraires de SVEDELIUS et

de KYLIN, sans preuve, que les divisions nucléaires aboutissant à la formation

des noyaux des carpotétraspores constituaient une méiose et que les carpotétra¬

spores haploïdes redonnaient directement un gamétophyte.

Très récemment, BODARD (1971) a démontré avec VHelminthocladia

senegalensis, que la division du carposporocyste engendrant les quatre tétra¬

spores, est une méiose. Cependant il restait encore à préciser, chez ces algues à

carpotétraspores, l’alternance de générations. Ce fut le but de ce travail.

Ayant eu la chance de récolter, au cours de plongées effectuées entre Banyuls-

sur-mer et Cerbère, au mois de septembre 1969, 1970 et 1971, le Liagora tetra¬

sporifera pourvu de carpotétraspores, nous en avons entrepris des cultures dans

1 espoir de résoudre le problème du rôle de la carpotétraspore et de son devenir.

A la même époque, ayant récolté une autre espèce du même genre, le Liagora

distenta, qui elle possède des carpospores indivises, nous avons tenté aussi d’en

réaliser des cultures pour établir une étude comparative entre ces deux espèces.

La culture de cette deuxième espèce présentait aussi un autre intérêt, à savoir

qu’elle permettait de faire une comparaison avec les résultats obtenus par VON

STOSCH avec le Liagora farinosa (1965) qui possède également des carpospores.

II. MATERIEL ET MÉTHODES

Le matériel qui a servi à la mise en route des cultures a été exclusivement ré¬

colté dans la région de Banyuls-sur-mer. Des échantillons ont été trouvés aussi

bien près du cap Béar, de l’anse des Elmes, qu’au voisinage du cap du Troc, du

cap l’Abeille et de l’anse de Terrambou, toujours dans les localités assez abritées

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

275

et à une profondeur n’excédant pas, ou rarement - 5 m. La fertilité des échantil¬

lons n’a été constatée qu’entre les mois d’août et septembre pour les années

1969, 1970 et 1971. D’autre part, aucun thalle n’a jamais été observé avant le

mois de mai, ce qui revient à dire que ces algues sont annuelles. La durée de vie

de leur forme macroscopique est très réduite, les thalles disparaissent à la mi-

octobre. Cette caractéristique a constitué une difficulté supplémentaire majeure

pour leur étude.

Ces observations, toutefois, sont propres à la région de Banyuls-sur-mer, car,

en ce qui concerne le Liagora tetrasporifera, BQRGESEN signale avoir trouvé des

échantillons fertiles aux Iles Canaries au mois de mars.

Après la récolte, les échantillons sont rapidement rapportés au laboratoire

pour préparer immédiatement les cultures. Les apex fertiles des thalles sont sé¬

lectionnés sous la loupe binoculaire. On les reconnaît aisément à la présence de

renflements rouge foncé sur la croûte blanche du Liagora tetrasporifera, rose

chez le Liagora distenta. Ces formations traversant la croûte calcifiée du thalle

et affleurant à sa surface, sont constituées par les gonimoblastes portant à l’ex¬

trémité de leurs filaments les carpotétraspores chez la première espèce et les

carpospores chez l’autre.

Ces apex, une fois isolés, sont déposés sur des lames de verre préalablement

dégraissées et stérilisées, de préférence à la surface non lisse (afin de faciliter

l’implantation des jeunes germinations), immergées dans un bac rempli d’eau de

mer fraîche, filtrée sur papier. On abrite contre les poussières, la lumière trop

vive et une température trop élevée, les échantillons générateurs de spores et on

laisse ainsi durant quarante huit heures pendant lesquelles les spores sont libé¬

rées et s’implantent sur les lames. Ces dernières avec les spores fixées sont ensuite

débarrassées des fragments macroscopiques et disposées dans des boîtes de Pétri

stérilisées remplies à demi de milieu de VON STOSCH modifié (1964) dont la

composition est la suivante :

NaNÛ 3

Na2HP04 + 12H20

FeS04 + 7 H 20 + 0,01 ml H 2 SO 4 conc.

MnCb + 4 H 2 O

E. D. T. A.

Cobalamine (B 12)

Aneurine HCl

Biotine

AS2O3

42,5 mg/litre eau de mer

10,75 mg/litre eau de mer

0,278 mg/litre eau de mer

0,0198 mg/litre eau de mer

3,72 mg/litre eau de mer

0,0007 mg/litre eau de mer

0,0086 mg/litre eau de mer

0,0061 mg/litre eau de mer

0,664 mg/litre eau de mer

0,197 mg/litre eau de mer

A ce milieu de culture a été ajouté, à raison de 5 ml par litre, une solution

d’oxyde de germanium (WEST, 1969) dont le rôle est d’empêcher la prolifé¬

ration des diatomées.

Les jeunes germinations sont éclairées en lumière du jour naturelle; des essais

nombreux, réalisés avec des éclairements variés, mais sans tenir compte de la lon¬

gueur d’onde, ont mis en évidence que les meilleurs résultats étaient toujours

Source: MNHN. Paris

276

A. COÛTÉ

obtenus en fournissant aux cultures la lumière du jour ou des éclairements très

voisins.

En ce qui concerne les températures auxquelles les algues sont soumises, ce

sont les valeurs situées entre 12 et 15 C qui sont les plus favorables à leur bon

développement, avec un rendement maximal pour la valeur de 12 .

Après deux à trois semaines de séjour dans ce milieu, nécessaires pour faire

disparaître totalement les diatomées, les jeunes individus sont transplantés à

l’aide d’une micropipette dans de nouvelles boîtes de Pétri contenant du milieu

de VON STOSCH normal, sans germanium. Cette transplantation est indispensa¬

ble pour isoler les germinations des nombreuses algues épiphytes implantées en

même temps que les spores, qui, si l’on se contentait seulement de changer de

milieu, risqueraient, en se développant, d’entraver les cultures. On est ainsi par¬

venu à obtenir des cultures unialgales.

Après la transplantation les milieux ont été régulièrement changés tous les

mois.

III. RÉSULTATS

A. COMPARAISON MORPHOLOGIQUE ET ANATOMIQUE DES DEUX

ESPECES.

On peut très facilement distinguer le Liagora distenta du Liagora tetraspori-

fera grâce à deux caractères, l’un morphologique, l’autre anatomique. Les deux

espèces présentent, en effet, toutes deux une dichotomie générale de leur thalle

mais, chez le Liagora distenta des petits rameaux supplémentaires apparaissent

de façon constante sur l’axe du thalle, ce qui n’est pas le cas chez le Liagora te-

trasporifera.

Anatomiquement on peut aussi séparer une espèce de l’autre, en particulier en

observant des coupes transversales des thalles. Chez le Liagora distenta les cellu¬

les de l’axe se distinguent nettement des rhizoïdes : leur diamètre est, en effet,

cinq fois plus grand et leur paroi beaucoup plus mince que celles des cellules rhi-

zoïdiennes, très réfringeantes. Par contre chez le Liagora tetrasporifera les cellu¬

les axiales se distinguent difficilement des cellules rhizoïdiennes : leur diamètre

est à peine deux fois plus grand et leur paroi très épaisse de sorte que l’on a du

mal à séparer les rhizoïdes des cellules de l’axe.

B. COMPARAISON DES APPAREILS SEXUELS DES DEUX ESPECES.

Les deux espèces étudiées ici diffèrent par leur mode de reproduction; en

effet, le Liagora tetrasporifera, très clairement décrit par BQRGESEN (1927),

est monoïque, c’est-à-dire que l’on trouve, réunis sur le même thalle, les ra¬

meaux carpogoniaux et les spermatocystes (Pl. Il, fig. 4), alors que le Liagora

distenta est dioïque, certains thalles ne portant que des rameaux carpogoniaux

PI. I. — 1 : Liagora distenta, portion de thalle femelle avec rameau carpogonial (flèche).

2 : L. distenta, portion de thalle mâle avec spermatocystes (flèches). 3 : L. distenta, go-

nimoblaste avec carposporocystes, soit vides (flèche simple), soit contenant la carpospore

(flèche double).

Toutes les échelles sont exprimées en jUm.

Source :MNHN. Paris

278

A. COÛTÉ

(Pl. I, fig. 1) d’autres seulement des spermatocystes (Pl. I, fig. 2). Cette particula¬

rité du Liagora distenta n’a été nettement mentionnée, jusqu’alors, que par un

seul auteur, HAMEL (1930), pour des échantillons provenant aussi de Méditerra¬

née. Des échantillons récoltés à Madère en 1966 par CABIOCH (com. pers.) sont

également dioïques. La dioïcité de cette espèce semble donc être un caractère

constant.

Si l’on considère maintenant les rameaux carpogoniaux des espèces concer¬

nées, peu de différences sont à noter. Ils sont respectivement portés par une

cellule d’un rameau de filament assimilateur, non distincte cytologiquement.

Les uns comme les autres sont composés de quatre à cinq cellules (B0RGESEN,

1927, dans les Algues marines des Canaries, mentionne, pour le Liagora tetraspo-

rifera, uniquement trois cellules pour le rameau carpogonial), dont l’aspect, bien

que très hyalin par absence de toute pigmentation, laisse supposer une grande

richesse en réserves, étant données les très nombreuses petites inclusions sphéri¬

ques contenues. La largeur des cellules composant l’appareil femelle est d’envi¬

ron 10 pm pour les deux espèces, mais on peut toutefois constater que les ra¬

meaux carpogoniaux du Liagora distenta ont un aspect plus trapu que ceux du

Liagora tetrasporifera dont le carpogone est d’ailleurs plus allongé en général.

Pour les deux espèces, le trichogyne s’allonge et apparaît à la surface de la

croûte.

Les spermatocystes des deux espèces ne présentent pas non plus de différence

nette. Leur diamètre n’excède pas 3 pm ce qui les rend difficilement observables.

Ils sont portés par les filaments assimilateurs, à l’apex de rameaux constitués de

petites cellules (3 pm de large sur 5 pn î de long), de sorte qu’ils sont générale¬

ment localisés dans la partie superficielle du thalle.

Après la fécondation, le carpogone subit une première division transversale

donnant ainsi une nouvelle cellule à partir de laquelle naissent les filaments spo-

rophytiques du gonimoblaste, composés de cellules grossièrement en forme de

tonnelet, de 5 pm environ de côté. Ces filaments constituent un bouquet dense

qui apparaît à la surface du thalle comme un petit coussin rouge foncé chez le

Liagora tetrasporifera (Pl. II, fig. 5) et rose chez le Liagora distenta (Pl. I, fig. 3).

La plupart du temps, d’ailleurs, l’importance des coussins est due à la fusion des

filaments sporophytiques de plusieurs rameaux carpogoniaux fécondés contigus.

Chez ces algues on ne voit pas d’involucre autour du gonimoblaste, bien que des

filaments stériles, issus de rameaux végétatifs voisins, soient entrelacés avec les

filaments gonimoblastiques.

Enfin, à l’extrémité des rameaux carposporophytiques ainsi développés, com¬

posés parfois seulement de deux cellules, prennent naissance des cellules globu¬

leuses dont l’aspect est different selon l’espèce considérée. Chez le Liagora tetra¬

sporifera la formation globuleuse de 8 à 10 pm environ de diamètre, est subdi¬

visée en quatre cellules nommées carpotétraspores (Pl. II, fig. 6); chez le Lia¬

gora distenta une seule cellule constitue cette formation globuleuse à l’apex du

filament gonimoblastique (Pl. I, fig. 3) : c’est un carposporocyste renfermant une

carpospore unique, de 10 pm de diamètre et de 20 pm de long environ, son allu¬

re générale étant piriforme.

PL II. — 4 : L. tetrasporifera, portion de thalle avec rameau carpogonial. 5 : L. tetrasporife¬

ra, portion de thalle avec un rameau carpogonial fécondé montrant les premiers filaments

gonimoblastiques. 6 : L. tetrasporifera, gonimoblaste mûr avec carpotétrasporocystes

(flèches). 7-8-9 : L. tetrasporifera, stades successifs de l’émission des carpotétraspores.

Leur forme amiboïde est nette ici.

Toutes les échelles sont exprimées en /im.

Source : MNHN. Paris

280

A. COÛTÉ

C. EMISSION DES SPORES.

Pour que la comparaison des stades communs aux deux espèces soit plus ai¬

sée, nous avons choisi de traiter non pas le cycle morphologique complet de cha¬

que algue successivement, mais de considérer parallèlement les différents stades

dans leur suite logique dans le temps, pour les deux espèces, lorsque cela était

possible.

Les carpotétraspores du Liagora tetrasporifera sont émises très rapidement

d’un seul bloc. Elles ne se séparent qu’une fois sorties du carpotétrasporocyste

(Pl. II, fïg. 7, 8, 9). Leur observation montre alors qu’elles sont plus denses que

l’eau de mer car elles tombent au fond du récipient. Elles ne cessent de modifier

leur contour pendant un temps assez long (de trois à cinq heures en moyenne)

par des déformations amiboïdes. Leur contenu est très dense et pigmenté, sans

toutefois qu’on puisse y distinguer un ou plusieurs plastes. Leur taille est d’envi¬

ron 8 à 10 pm.

Les carpospores du Liagora distenta ont la même cytologie que les carpotétra¬

spores du Liagora tetrasporifera. Leur taille est légèrement supérieure (10 à

12 pm). Elles sont douées également de modifications amiboïdes pendant quel¬

ques heures encore après leur émission. VON STOSCH a observé aussi le même

phénomène chez le Liagora farinosa (1965).

D. GERMINATION DES SPORES,

a. chez le Liagora distenta :

Les carpospores se fixent rapidement au substrat, en l’occurence la lame de

verre, auquel elles adhèrent solidement. Vingt-quatre heures après leur fixation,

elles se divisent pour donner un filament unisérié. Deux modes de germination

sont apparus ici : ou bien la spore se vide de son contenu (comme chez le Nema-

lion pulvinatum (UMEZAKI, 1967), le Nemalion vermiculare (UMEZAKI,

1967)...) au profit de la cellule nouvellement formée et dégénère rapidement,

ou bien la spore conserve une cytologie normale et participe, comme une banale

cellule végétative, à l’édification de la partie prostrée.

Le filament engendré par la spore germante est composé de cellules allongées,

de 20 à 30 pm de long sur 5 pm de large. La plupart du temps, ce n’est que lors¬

qu’il a environ dix cellules qu’on observe les premières ramifications, mais il

arrive qu’il s’en forme déjà une alors que le filament n’est encore constitué que

de deux ou trois cellules. Les ramifications du filament original sont ensuite très

nombreuses, engendrant ainsi un protonéma très enchevêtré. Sur les lames où

ont été récoltées les carpospores, on observe d’ailleurs, en général, les nombreux

protonémas rouge vif enchevêtrés, issus de chaque carpospore. Ce n’est que sur

des carpospores isolées sur la lame de verre lors de l’émission, ou sur des carpo¬

spores mises en culture à l’écart à l’aide de la micropipette, que l’on peut bien

observer le développement individuel.

Cette partie rampante donne naissance à des filaments dressés unisériés, cons-

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

281

titués de cellules atteignant 40 pm de long et 10 Jim de large. Ces cellules, bien

que plus longues et plus larges que celles de la partie rampante, ont la même

cytologie, à savoir un plaste unique, plurilobé et pariétal, un gros pyrénoïde et

de nombreux granules de rhodamylon, qui, très souvent, gênent l’observation.

L’allure de la partie dressée est celle d’un Acrochaetium. VON STOSCH, en

1965, avait déjà signalé ce fait à propos du tétrasporophyte du Liagora farinosa

et cela semble être la caractéristique de la plupart des tétrasporophytes des autres

Némalionales cultivées jusqu’à présent.

Deux mois environ après la mise en culture des carpospores, les tétrasporo-

cystes sont apparus sur ces filaments dressés du protonéma hétérotriche (Pl. III,

fig. 10). Ils se forment, soit à l’extrémité du filament dressé lui-même, en bou¬

quets denses, soit à l’extrémité de courts rameaux nés du filament principal. Ils

sont sphériques et leur diamètre est d’environ 20 Jim (Pl. III, fig. 11). Leur

cytologie est très différente de celle des cellules végétatives. En effet, alors que

ces dernières ont un contenu très pigmenté, les tétrasporocystes ont un contenu

pâle et homogène. On n’y repère ni plaste, ni pyrénoïde, ni granule de rhodamy¬

lon, mais la réfringence de la cellule est forte, ce qui laisse supposer une grande

richesse en réserves.

Pour les deux raisons énoncées ci-dessus, cette phase du cycle a été difficile à

repérer sur le matériel vivant, les tétrasporocystes, petits et pâles, passant la plu¬

part du temps inaperçus à la loupe binoculaire et ce n’est pratiquement qu’à

'objectif à immersion que l’on peut déceler la segmentation en quatre de leur

contenu.

Remarquons encore que chez une autre Nemalionale, le Nemalion vermicu-

are, UMEZAK1 (1967) a vu apparaître des tétrasporocystes non pédicellés, insé-

és directement sur le filament dressé du protonéma hétérotriche issu de la ger-

nination de la carpospore.

La disposition des tétraspores à l’intérieur du tétrasporocyste est, en général,

ie deux types : soit tétraédrique, soit cruciée, alors que chez d’autres Némaliona-

es telles le Pseudogloiophloea confusa ou le Scinaia japonica, elle peut, en plus

les formes précédentes, être, soit décussée, soit zonée.

La durée d’existence des tétrasporocystes est très courte, au plus trois ou qua¬

re jours, ce qui rend encore plus difficile leur observation. Dans les cultures réa¬

isées, il ne s’en est formés que deux fois, une en décembre 1970 et une en

uillet 1971, sur des tétrasporophytes issus de carpospores émises et récoltées en

eptembre 1970. Il n’est toutefois pas exclu que d’autres tétrasporocystes

oient nés à d’autres périodes de l’année et soient passés inaperçus, pour les

aisons données ci-dessus. D’autre part, s’il n’y a eu effectivement que deux pé¬

riodes de fertilité des filaments tétrasporophytiques, c’est que, peut-être, les

conditions de milieu n’ont pas été favorables. Il n’a pas encore été possible,

en effet, de préciser les conditions d’apparition des tétrasporocystes, ceci pour

des raisons de temps et de matériel. Des essais sont toutefois en cours, basés

sur les résultats de FRIES (1967) qui constate l’induction de l’apparition des

tétrasporocystes chez le Nemalion multifidum lorsque le taux des phosphates

PL III - 10 : L. distenta, tétrasporocyste. 11 : L. distenta, portion de rameau tétrasporo-

phytique avec un tétrasporocyste mûr et deux immatures. 12 : L. distenta, tétrasporo-

cystes immatures non segmentes et tétrasporocystes vides dans lesquels de nouvelles

cellules repoussent.

Toutes les échelles sont exprimées en /Um.

Source : MNHN, Paris

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

283

diminue, et sur les très brillants résultats de RAMUS (1969) avec le Pseudo-

gloiophloea où les tétrasporocystes apparaissent en grand nombre lorsque la

concentration en nitrates diminue.

Les tétraspores sont libérées groupées, l’apex du tétrasporocyste éclatant.

Elles se dissocient rapidement et tombent au fond de l’eau, leur densité étant

légèrement plus forte que celle de cette dernière. Comme les carpospores, elles

sont, pendant plusieurs heures, l’objet de déformations amiboïdes. Leur diamè¬

tre est d’environ 15 à 20 /un. Parfois, on trouve des tétraspores plus volumi¬

neuses, ce fait étant dû à une turgescence momentanée (Pl. IV, fig. 13 et 14).

Cet état turgescent des spores est favorable à l’observation du plastidome qui

apparaît composé de plusieurs plastes étoilés, munis chacun d’un gros pyrénoïde

bordé de massifs granules de rhodamylon.

Après émission des tétraspores, la paroi apicale du tétrasporocyste vide

s’effondre, tandis que, la plupart du temps, une nouvelle cellule croît dans l’an¬

cienne enveloppe (Pl. III, fig. 12) qui s’est repliée vers l’intérieur. Sur les échan¬

tillons en culture, ces repousses ont toujours donné naissance à des cellules de

cype végétatif. RAMUS, dans le cas du Pseudogloiophloea confusa (1969) et

UMEZAKI, avec le Scinaia japonica (1971), montrent que, dans les tétrasporo¬

cystes vides, peuvent se reconstituer de nouvelles cellules capables de donner

naissance, à nouveau, à des tétraspores. Rien n’interdit de penser qu’ici il en soit

de même.

Par ces repousses végétatives, le tétrasporophyte poursuit sa croissance, se

amifiant activement pour constituer finalement un buisson filamenteux d’un

ose intense, pouvant atteindre 2 à 3 cm de haut. Jamais, dans la nature, ces or-

anismes n’ont été rencontrés, mais, il est vrai que nous n’avons jamais eu l’occa-

ion de pouvoir les rechercher à Banyuls-sur-mer en décembre ou janvier. Il

aut dire aussi, qu’étant donnée leur petite taille, ils ont facilement pu passer

aaperçus et que leur ressemblance avec les espèces du genre Acrochaetium a

)u entraîner une confusion. Il serait néanmoins très intéressant de les trouver

lans la nature pour s’assurer de leur existence réelle et confirmer les résultats

les cultures. A ce propos, il faut noter que, seule de tous les algologues ayant

lémontré l’existence d’un tétrasporophyte dans le cycle d’une Nemalionale,

RIES a réussi à retrouver celui-là in situ (Nemalion multifidum, 1969).

La germination des tétraspores s’effectue quelques jours seulement après leur

ixation au substrat, parfois même 24 heures après. La première indication de la

germination est le développement d’un petit renflement de la paroi de la spore,

qui s’allonge pour devenir l’apex du filament initial prostré (Pl. IV, fig. 15). De

temps en temps, deux filaments prostrés se développent à partir de la même spo¬

re. Ces filaments naissant de la germination de tétraspores sont tout à fait analo¬

gues, par leur cytologie et leurs dimensions de cellules, à ceux engendrés par la

germination des carpospores. Les cellules qui les composent ont 25 à 30 pm de

long sur 7 à 8 /im de large. Elles renferment un plaste unique, étoilé, pariétal,

muni d’un gros pyrénoïde. Le jeune filament rampant unisérié se ramifie rapi¬

dement, parfois même après la formation de la première cellule, dans le plan du

substrat, donnant ainsi naissance à un protonéma rampant, formant, à un stade

Source : MNHN. Paris

pl - rv - 13 et 14 : L. distenta, tétraspores turgescentes montrant de nombreux plastes plu-

lobés. 15 : L. distenta, germination de deux tétraspores. 16 : L. distenta, gamétophyte

nouvellement formé, à l’extrémité de son filament porteur (flèche), ancien filament

dressé du protonéma hétérotriche né de la germination d’une tétraspore. 17 : L. disten¬

ta, jeune gamétophyte avec sa couronne de poils unicellulaires dans la partie apicale.

Toutes les échelles sont exprimées en /Jm.

Source : MNHN, Paris

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

285

ultérieur, des filaments dressés. Ce protonéma hétérotriche, de couleur rouge vif,

a un aspect tout à fait semblable à celui du protonéma hétérotriche tétrasporo-

phytique. Comme ce dernier, il présente parfois des poils hyalins, unicellulaires,

avec une grande vacuole, le cytoplasme n’étant visible qu’à l’apex. Ces poils

naissent des cellules rampantes.

Il faut toutefois mentionner que l’extension de ces nouveaux protonémas est

plus limitée que celle des protonémas tétrasporophytiques. Cela est-il dû au

mode d’entretien des cultures qui souvent a entraîné la fragmentation des fila¬

ments, ou cela est-il le fait de l’haploïdie présumée des cellules ? Il est vrai que

les filaments, ici, sont constitués de cellules un peu plus petites (25 à 30 /tm sur

7 à 8 /tm) que celles qui contituent les filaments tétrasporophytiques (40 /tm sur

10 /tm), diploïdes, elles. Aucune réponse valable n’a pu être encore fournie à

cette question.

Les cellules assurant la croissance du protonéma, ou encore les apicales des fi¬

laments rampants, ont un contenu très dense mais non pigmenté et sans pyré-

noïde distinct.

C’est sur les filaments dressés du protonéma hétérotriche que naissent, à

partir d’une ou deux cellules, souvent apicales ou subapicales du filament, des

bourgeonnements très denses de rameaux à cellules plus courtes et plus renflées

que celles du filament; leur diamètre moyen est d’environ 10 /tm. Ce sont ces

bourgeons, très compacts, qui engendrent les thalles gamétophytiques. En

effet, le bourgeon s’organise rapidement, montrant une zone centrale multi-

axiale non pigmentée, faite de cellules très claires, longues de 60 /im en moyenne

et larges de 10 /im. Ces cellules, constituant les filaments axiaux, portent à leur

partie supérieure un seul rameau fait de cellules très pigmentées, en forme de

tonnelet, d’environ 12 /im de diamètre, qui possèdent un plaste pariétal unique

plurilobé avec un très volumineux pyrénoïde.

A la base de ce thalle embryonnaire, s’allongent des filaments unisériés, aux

cellules longues et étroites (50 /im sur 10 /im), légèrement pigmentées. La

disposition de ces filaments est rayonnante, donnant ainsi au jeune thalle un

aspect un peu arachnéen (Pl. IV, fig. 16). Ce sont les futurs rhizoïdes, qui cons¬

titueront l’appareil fixateur propre du nouvel individu formé, lorsqu’il aura

acquis son indépendance.

Ainsi on voit que le thalle gamétophytique ne naît pas directement de la

partie prostrée. Chez le Liagora distenta, le jeune gamétophyte est donc suppor¬

té, dans la première phase de sa vie, par un filament dressé du protonéma hétéro¬

triche, engendré après germination d’une tétraspore. Ce n’est qu’après quelques

jours de croissance du nouveau thalle que le filament générateur et porteur va se

courber sous la masse grandissante du jeune individu, amenant ce dernier au

contact du substrat. Dès cet instant, les rhizoïdes particuliers du nouveau thalle

se fixent solidement. Le filament générateur se confond alors avec les rhizoïdes

et participe, à son tour, à l’arrimage au substrat. Très souvent, il se brise et dégé¬

nère, libérant totalement de son protonéma originel le jeune gamétophyte.

On peut supposer, ici, que la dispersion des thalles et leur propagation dans la

P ' ,Y 18 : L : distent ?’ zone apicale d’un jeune gamétophyte. Les filaments latéraux de

axe apparaissent très clairs alors que les filaments latéraux sont fortement pigmentés.

IV : L. dtstenta, details de la base de deux filaments latéraux d’un jeune gamétophyte,

chacune avec un rhizoïde (flèche). 20 : L. distenta, fragment d’un jeune thalle gaméto-

pnytique obtenu en culture, présentant de petits rameaux latéraux (flèches) qui sont

caractéristiques de cette espèce.

Toutes les échelles sont exprimées en /im.

Source :MNHN. Paris

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

287

nature, sont dues à la fragilité des filaments générateurs qui, sous l’action de la

houle, peuvent facilement se briser, libérant ainsi les jeunes individus dont la

fixation au substrat sera fonction des courants.

Remarquons, ici, que dans les cultures, tous les thalles formés ne se sont pas

toujours présentés au sommet d’un filament porteur, mais bien souvent directe¬

ment sur une partie rampante réduite. Cette particularité est due au morcelle¬

ment fréquent des filaments dressés du protonéma hétérotriche, lors du nettoya¬

ge des cultures. Les fragments isolés des filaments dressés, à potentialité généra¬

trice de gamétophyte, se fixent et reconstituent une partie rampante réduite

parfois à quelques filaments, mais organisée non comme un protonéma mais plu¬

tôt comme un cladome (voir le même phénomène chez le Liagora tetrasporife¬

ra ). C’est sur cette partie prostrée que naît le gamétophyte dans de nombreux

cas.

Les gamétophytes, dans nos cultures, sont apparus pour la première fois au

mois de mars, soit environ six mois après l’émission des carpospores dont ils

dérivent (Pl. IV, fig. 17, Pl. V, fig. 18 -19 - 20).

Il faut noter ici que les résultats obtenus par BOILLOT avec 1 ’Helminthora

divaricata (1971) en culture, présentent une étonnante similitude avec les nôtres.

Mais, comme elle, nous n’avons pu observer avec précision l’organisation des ra¬

meaux dont l’association engendre un gamétophyte.

Le Liagora distenta, comme le Liagora farinosa, possède donc trois généra¬

tions : un gamétophyte macroscopique différencié en cladome multiaxial, un

carposporophyte parasite sur le gamétophyte et morphologiquement très réduit,

et un tétrasporophyte nain ressemblant au protonéma du gamétophyte. Son

cycle peut donc être défini comme trigénétique hétéromorphe et vraisemblable¬

ment haplodiplophasique. Le tétrasporophyte réduit à un thalle hétérotriche,

analogue au protonéma juvénile du gamétophyte, peut être considéré comme

néoténique.

b. chez le Liagora tetrasporifera :

Vingt quatre à quarante huit heures après leur émission, les carpotétraspores

germent (Pl. VI, fig. 21), donnant naissance à un filament unisérié, quelques fois

à deux. Comme pour le Liagora distenta, on observe les mêmes caractéristiques

concernant la spore, à savoir qu’elle peut soit se vider et dégénérer après avoir

germé (Pl. VI, fig. 22), soit conserver son contenu et persister alors comme une

cellule végétative (Pl. VI, fig. 23). Avant leur germination, elles sont aussi l’objet

de déformations amiboïdes. Les cellules végétatives du filament de germination

renferment un plaste unique, étoilé, pariétal, muni d’un volumineux pyrénoïde,

bordé de gros granules de rhodamylon (Pl. V, fig. 24 - 25). Elles ont, en moyen¬

ne, 20 pm de long et 15 pm de large. Leur aspect général, tant que le filament

n’a que quelques cellules (3 à 5 au plus), est celui d’un tonnelet.

Ce filament unisérié est à l’origine d’un protonéma hétérotriche, constitué

d’une partie rampante et d’une partie dressée, tout à fait semblable, en aspect et

en dimension, à celui engendré par la germination des tétraspores du Liagora

PI. VI — 21 : L. tetrasporifera, début de germination d’une carpotétraspore. 22 : L. tetra-

sporifera, début de germination d’une carpotétraspore dont le contenu s’est vidé pour

donner naissance au filament germinatif. 23 : L. tetrasporifera, carpotétraspore et son

filament germinatif. 24 : L. tetrasporifera, carpotétraspores et leurs filaments germina¬

tifs. 25 : L. tetrasporifera, extrémité d’un filament germinatif de carpotétraspore. La

cellule terminale possède une cytologie très différente de celle des autres cellules. 26 :

L. tetrasporifera, protonéma engendré par la germination d’une carpotétraspore. Seule la

partie prostrée est visible ici.

Toutes les échelles sont exprimées en jLtm.

Source :MNHN, Paris

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

289

distenta. En effet, le filament initial, après avoir atteint une longueur d’environ

dix cellules, se ramifie activement pour donner une lame d’un beau rouge vif

(Pl.VI fig. 26). A partir de cette lame prostrée se dressent des filaments unisériés

du type Acrochaetium (Pl. VII, fig. 27). Les cellules les composant sont allon¬

gées et cylindriques (50 pm de long et 12 fim de large). Leur contenu est carac¬

térisé par un plaste plurilobé, pariétal, muni d’un volumineux pyrénoïde à très

gros granules de rhodamylon. On a d’ailleurs pu suivre la formation de l’organi¬

sation du contenu cellulaire dans les parties apicales de certains filaments et

montrer qu’il n’existe qu’un seul plaste par cellule, mais si lobé, au stade adulte,

que l’on peut être amené à croire à la présence de plusieurs plastes. Les cellules

apicales des filaments ont un contenu non pigmenté et très réfringent, avec de

nombreux granules dont la présence atteste l’existence de nombreuses réserves.

C’est sur ces filaments dressés que naissent directement les bourgeons gamé-

tophytiques. Il y a d’abord ramification assez lâche du filament dressé, puis, dans

la partie subterminale, quelques cellules sans aucune caractéristique spéciale,

bourgeonnent activement sur un même rameau ou sur des ramifications voisines

(Pl. VII, fig. 28) du même filament dressé. Ce bourgeonnement engendre de nou¬

veaux filaments dont la première cellule est à l’origine de deux types de ra¬

meaux, simultanément : les uns, faits de cellules cylindriques allongées (50 à

60 pim de long et 6 à 7 pim de large), à phototropisme négatif, les autres, faits de

cellules en tonnelet (12 pim de long et 8 pim de large), à phototropisme positif.

Les premiers sont fort peu pigmentés alors que les autres sont d’un rouge très vif.

La première division de la cellule initiale de ces rameaux engendre donc deux

cypes de cellules à potentialités très différentes, les unes destinées à jouer un rôle

fixateur, non photosynthétiques, les autres, au contraire, destinées à constituer

les axes d’un futur thalle gamétophytique. Il serait intéressant d’étudier la phy¬

siologie de ce type de cellule.

Comme on l’a déjà noté pour le Liagora distenta, la formation des jeunes

gamétophytes (Pl. VII, fig. 29) est ici aussi très semblable à celle observée par

BOILLOT chez VHelminthora divaricata (1971), mais ici la distinction entre

les rameaux rhizoïdiens et les rameaux axiaux est beaucoup plus nette.

Ici, comme chez le Liagora distenta et le Liagora farinosa, le nouvel individu

formé est porté par le filament dressé du thalle hétérotriche engendré par la germi¬

nation de la carpotétraspore. Chez le Liagora harveyana, il semble se former directe¬

ment à la germination de la carpotétraspore mais WOELKERLING (qui a cultivé

cette algue, voir ABBOTT, Yamadaella, 1970) n’a-t-il pas été abusé par le phéno¬

mène décrit page 287.

Le Liagora tetrasporifera présente donc une alternance de générations digéné-

tique, les carpotétraspores produisant directement le gamétophyte. WOELKER¬

LING est parvenu, semble-t-il, à la même conclusion avec le Liagora harveyana

Zeh.

Le Liagora tetrasporifera, comme, sans doute, les autres Nemalionales à car¬

potétraspores, a donc une alternance de générations digénétique, le gamétophy¬

te étant directement produit par les carpotétraspores issues du carpotétrasporo-

PI. VII. — 27 : L. tetrasporifera, partie dressée du protonéma né de la germination d’une

carpotetraspore, avec début de la formation de bourgeons gamétophytiques. 28 : L. te¬

trasporifera, detail des rameaux engendrant un gamétophyte. 29 : L. tetrasporifera, jeu-

ne gametophyte porté par les filaments dressés dont il est issu.

Toutes les échelles sont exprimées en jUm.

Source : MNHN, Paris

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

291

phyte (B0RGESEN l’avait très clairement supposé dès 1927). La méiose, selon

toute vraisemblance (comme BODARD l’a démontré chez 1 ’Helminthocladia

senegalensis , 1971), doit s’effectuer lors de la formation des carpotétraspores.

Le cycle nucléaire est, par conséquent, haplodiplophasique, avec un raccourcisse¬

ment de la durée de la diplophase, limitée, en l’absence de tétrasporophyte indé¬

pendant, au seul carpotétrasporophyte.

On pourrait dire aussi, avec MAGNE (sous presse), que le Liagora tetraspori¬

fera possède une alternance de générations trigénétique : le gamétophyte macro¬

scopique porte les deux autres générations; le carposporophyte représenté par

les quelques cellules du gonimoblaste développé à partir du carpogone fécondé

in situ, et le tétrasporophyte réduit à la carpospore, le carposporocyste, par la

méiose qu’il subit, donnant naissance directement à un tétrasporocyste. Le car¬

potétrasporophyte contiendrait ainsi les générations carposporophytique et

tétrasporophytique condensées. Une évolution régressive importante aurait

donc frappé, ici, deux des trois générations fondamentales caractérisant le cycle

de toutes les algues rouges (FELDMANN, 1952).

E. EXISTENCE DE MONOSPORES CHEZ LE LIAGORA DISTENTA.

Sur le tétrasporophyte de cette espèce, nous avons observé, une fois

l’émission des tétraspores effectuée, l’apparition de monosporocystes. Les mono¬

spores qui s’en échappent, en germant, redonnent de nouveaux tétrasporophy-

tes. Il s’agit donc, ici, de multiplication végétative. Cette possibilité de donner

naissance à des monospores a été notée chez plusieurs autres Nemalionales.

C’est ainsi que les tétrasporophy tes du Liagora farinosa Lamour.(VON STOSCH,

1965), du Nemalion helminthoides (Velley) Batters (CHANG, 1962), du Nema-

lion pulvinatum Grünow (UMEZAKI, 1967), du Nemalion multifidum (Weber

et Nohr) J. Ag. (FRIES, 1967) et du Pseudogloiophloea confusa (Setchell)

Levring (RAMUS, 1969), sont capables de se reproduire par monospores. Par

contre, aucune monospore n’a été observée encore sur les filaments du protoné-

na gamétophytique. Ceci ne signifie toutefois pas qu’il soit incapable d’en for¬

mer, mais les conditions nécessaires à l’apparition de celles-ci n’ont sans doute

pas été réunies dans nos cultures.

Chez le Liagora tetrasporifera, aucune monospore n’a été formée ni émise

par le protonéma gamétophytique.

VON STOSCH, de même, a constaté que les monospores ne se sont pas

développées sur les gamétophytes du Liagora farinosa en culture, mais sur

les échantillons qu’il a récoltés aux Iles Lipari, elles semblaient présentes.

IV. DISCUSSION ET CONCLUSION

Avant de conclure sur le cycle du Liagora tetrasporifera et sur celui du Liago¬

ra distenta, il faut apporter une remarque importante concernant les résultats

obtenus en culture. Dans la nature, le développement des différentes phases de

292

A. COÛTÉ

ces algues est lié à de nombreux facteurs externes de leur environnement. Les

échantillons cultivés au laboratoire, en milieu artificiel, ne sont pas dans les

conditions normales, il faut donc accepter les résultats obtenus avec le maximum

de prudence, quand on sait que l’expression phénotypique d’un génotype peut

varier selon les conditions extérieures.

Cependant, la découverte, dans la nature du sporophyte du Nemalion multi-

fidum par FRIES (1969), sur la côte occidentale de Suède, dont elle avait mis

la présence en évidence, en cultivant au laboratoire des fragments de thalles

gamétophytiques non fertiles, est une confirmation spectaculaire de l’expéri¬

mentation et la preuve que les individus formés en milieu artificiel peuvent être

similaires de ceux formés dans les conditions normales.

Il serait donc souhaitable, pour que les présents résultats expérimentaux

prennent toute leur valeur, que soient trouvés dans la nature les formes que l’on

a vues se développer in vitro. Mais leurs dimensions très réduites et leur ressem¬

blance avec les espèces du genre Acrochaetium rendent ce travail difficilement

réalisable.

En tenant donc compte des remarques précédentes, on peut résumer les résul¬

tats obtenus comme suit :

- le cycle de développement du Liagora tetrasporifera présente une alternance

de générations digénétique (ou trigénétique selon MAGNE, cf. ci-dessus), les

carpotétraspores engendrant directement un protonéma hétérotriche nain, sur les

filaments dressés duquel apparaissent de nouveaux gamétophytes. On trouve

donc une génération, selon toute vraisemblance diploïde, composée par les

filaments gonimoblastiques parasites du gamétophyte parental, et une génération

sans doute haploïde, composée par le protonéma hétérotriche et les gaméto¬

phytes qu il engendre. Les observations faites sur le Liagora harveyana semblent

confirmer ce point de vue, du moins pour ce qu’on en sait par ABBOTT ( Yama-

daella, 1970). Le tableau suivant réunit toutes les données précédentes :

GAMETOPHYTE (N) CARPOTETRA.

-p EC0NDATI0N -►

MONOÏQUE

FRONDE CLADOMIENNE

PROTONEMA STERILE

CARPOTETRASPORES (n)-*- MEIOSE ?

SPOROPHYTE

PARASITE (2N)

Source : MNHN. Paris

LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

293

- De son côté, le Liagora distenta a un cycle de développement qui présente

une alternance de générations trigénétique, comprenant : un gamétophyte ma¬

croscopique naissant d’un protonéma hétérotriche, différencié en cladome multi-

axial, un carposporophyte parasite sur le gamétophyte parental, morphologi¬

quement très réduit, et un tétrasporophyte nain né de la germination de la carpo-

spore, ressemblant au protonéma du gamétophyte. Son cycle peut donc être dé¬

fini comme trigénétique hétéromorphe et vraisemblablement haplodiplophasi-

que, les générations diploïdes étant constituées sans doute par les filaments goni-

moblastiques ou encore carposporophytiques, et par le tétrasporophyte, tous

deux de dimensions réduites, et la génération haploïde constituée par le proto¬

néma nématothallien gamétophytique et la fronde fertile qu’il porte. Ces résul¬

tats sont résumés par le tableau suivant :

GAMETOPHYTE (N).

DIOIQUE

FRONDE CLADOMIENNE

FERTILE

FECONDATION

ROTONEMA NEMATOTHALLIEN

STERILE

ETRASPORES (N) -*■

MEIOSE ?

CARPOSPOROPHYTE (2N)

PARASITE

MONOSPORES ;

: t :

i i i

t ! T

-—TETRASPOROPHYTE (2N)

NEMATOTHALLE FERTILE

L’existence d’un tétrasporophyte chez le Liagora distenta confirme, avec

ON STOSCH (1965), FRIES (1967), UMEZAKI (1967, 1971), BOILLOT

1968) et RAMUS (1969), les assertions de MAGNE à propos des Némalionales

c contribue à réfuter l’opinion de SVEDELIUS (1915) et de KYLIN (1916),

laçant la méiose dans le carpogone, immédiatement après la fécondation. La

lassification des Némalionales selon KYLIN (1956) est donc à modifier.

Ce tétrasporophyte est néoténique; c’est en effet le protonéma né de la carpo-

•pore qui devient fertile à ce stade juvénile, alors que le gamétophyte se déve-

oppe sur un protonéma stérile, issu de la tétraspore.

294

A. COÛTÉ

Les tétraspores sont disposées de deux manières dans les tétrasporocystes du

Liagora distenta : cruciée et tétraédrique. Il en est de même chez 1 e Liagora fari-

nosa. Chez le Pseudogloiophloea confusa, chez le Scinaia furcellata et le Scinaia

japonica, la disposition des tétraspores peut être, en plus des deux précédentes,

zonée et décussée. Le mode de segmentation des tétrasporocystes n’a donc,

selon toute vraisemblance, aucune signification taxinomique dans ce groupe.

Le tétrasporophyte du Liagora distenta, tout comme celui du Liagora farino-

sa, du Nemalion multifidum, du Nemalion helminthoides , du Nemalion pulvina-

tum et du Pseudogloiophloea confusa, est capable de se reproduire par monospo¬

res. Il est donc totalement indépendant du gamétophyte. Ce dernier, au contrai¬

re, dépend totalement, pour son existence, du tétrasporophyte, car il ne peut

pousser qu’à partir de tétraspores produites dans les tétrasporocystes du tétra¬

sporophyte, et il manque de moyen de multiplication végétative (absence de

monospores mentionnée aussi par VON STOSCH chez le gamétophyte du Liago¬

ra farinosa).

Les conditions d’apparition des tétraspores, des monospores et des bourgeons

gamétophytiques restent à préciser. La caryologie de ces deux espèces demeure

aussi une inconnue actuellement et doit être appronfondie pour confirmer la

localisation présumée de la méiose, au moment de la formation des carpotétra-

spores chez le Liagora tetrasporifera, et des tétraspores chez le Liagora distenta.

Enfin, l’organisation des axes de la zone centrale des thalles gamétophytiques,

à partir des bourgeons primordiaux, et, surtout, la différenciation des frondes ga¬

métophytiques multiaxiales dérivant d’une cellule unique, soit tétraspore pour le

Liagora distenta, soit carpotétraspore pour le Liagora tetrasporifera, sont deux

problèmes qui demeurent entiers.

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ABBOTT, I. A., 1970 - Yamadaella, a new genus in the Nemaliales (Rhodophyta). Phycolo-

gta 9, 2 :115-123. J

AGARDH, C. A., 1823 — Species Algarum. XXVIII Liagora, I. Liagora distenta, 394-395.

AGARDH, J. G., 1851 -Sp. G. et O. Alg. LXVTI Liagora, 3. Liagora distenta, 426-427.

BISHOFF, H. W., 1965 -Thorea rickei, sp. nov., and related species. J. Phycol. I. 111.

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nale nouvelle a carpotetraspores et à cycle haplodiplophasique. Phycologia 10, 4 :361-

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LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

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LIAGORA TETRASPORIFERA ET LIAGORA DISTENTA

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299

THE PRESENCE OF TETRASPORANGIA AND

CARPOSPOROPHYTES ON THE SAME THALLUS

IN PTEROSIPHONIA THUYOIDES

H. M. PARKES *

SUMMARY. — The simultaneous occurence o£ tetrasporangia and carposporophytes in

Pterosiphonia thuyoides (Harv. in Mackay) Schm. is recorded from Ireland.

RÉSUMÉ. — La présence simultanée des tétrasporanges et des carposporophytes de Ptero-

siphonia thuyoides (Harv. in Mackay) Schm. est signalée en Irlande.

While carrying out observations on species of Pterosiphonia to be found on

he coast of county Dublin a specimen of Pterosiphonia thuyoides (Harv. in

dackay) Schm. bearing tetrasporangia and carposporophytes was collected at

'.andycove (Irish National Grid 0 26 28) in september 1960.

The specimen was normal in appearance as were the fruiting bodies. The te-

rasporangia, which were carried on the ultimate branches of the thallus, were

îumerous and many were mature. At the base of these fertile branches four

arposporophytes were found, one containing fully developed carpospores.

Unfortunately this specimen was preserved before these facts were observed

■o that it was not possible to carry out any culture studies.

At Sandycove, where P. thuyoides is found growing in pools in the lower

ittoral, phenological observations of this species were kept during a three year

.'eriod. These indicated that the main fruiting season for both types of sporangia

s summer and autumn and that tetrasporic plants predominate. No other «ab-

îormalities» were found.

The occurence of tetrasporangia and sexual organs on the same thallus among

the species of Rhodophyceae is an established fact and has been discussed by

/arious authors (DIXON 1961; DREW 1951, 1955; FRITSCH 1945; LAWSON

& RUSSELL 1967). In the case of the genus Pterosiphonia the phenomenon has

* 32 Eglinton Road, Dublin, Eire.

Rev. Algol., N. S., 1976, XI, 3-4 : 299-301.

Source : MNHN, Paris

300

H. M. PARKES

only been recorded in one of the species, P. parasitica (Huds.) Falkenb., by

LODGE (1945/7) and SUNESON (1940). There do not appear to be any publi-

shed records for such occurences in P. thuyoides.

The Sandycove material has been deposited in the herbarium of the Botany

Department of University College, Galway.

BIBLIOGRAPHY

DIXON, P. S., 1961 — The occurence of tetrasporangia and carposporophytes on the same

thallus in Euthora cristata (L. ex Turn.) J. Ag. Can. J. Bot. 39 : 541-543.

DREW, E. M., 1951 — Rhodophyta. In Manual of Phycology, Smith, G. M. Ed., Waltham

167-191.

DREW, K. M., 1955 — Life historiés in the algae with spécial reference to the Chlorophyta

Phaeophyta and Rhodophyta. Biol. Revs. Cambridge Phil. Soc. 30 : 343-390.

FRITSCH, F. E., 1945 — The structure and reproduction of the algae. Vol. II. Cambridge.

LAWSON, R. P., & RUSSELL, G., 1967 — Simultaneous occurence of carposporophytes

and Tetrasporangia in Polysiphonia urceolata. Br. phycol. Bull. 3 : 239-250.

LODGE, S. M., 1945/7 — Additions to algal records for the Manx région. Rep. Mar. Biol.

Stn. Pt. Erin. 58-60 : 59-62.

SUNESON, S., 1940 — Studies on the structure and the reproduction of Pterosiphonia

parasitica. Svensk. bot. Tidskr. 34 : 315-333.

Source : MNHN, Paris

PTEROSIPHONIA THUYOIDES

301

Fig. 1. — Part of frond of Pterosiphonia thuyoides bearing tetrasporangia and carposporo-

phytes. x 22; Fig. 2. — Enlargement from fig. 1 of a carposporophyte with carpospores.

x 100; Fig. 3. — Enlargement from fig. 1 of a mature tetrasporangium. x 400.

Photographs by Mr P. Cooke.

303

THE MARINE ALGAE OF IVORY COAST AND

CAPE PALMAS IN LIBERIA (GULF OF GUINEA)

David M. JOHN *

SUMMARY. — This annotated list of marine algae from Ivory Coast and Liberia recognises

103 separate entities of which 95 hâve been identifîed to species. Over a third ofthe algae

are reported for the first time from these two countries. Information on the ecology,

reproductive status, local distribution in the Gulf of Guinea, details of collection and

features of spécial taxonomie interest, are included for each of the separate entities.

INTRODUCTION

The first general account of the littoral ecology of the rocky shores of Ivory

Joast and also Cape Palmas in Liberia has only recently been published (JOHN

972). Sporadic collecting of marine algae has taken place in these two countries

irior to this ecological work but only a few of these hâve been reported in the

ather scattered literature relating to West Africa. Mostly single records are given

or Ivory Coast in publications by AMOSSE (1970), BODARD (1966a, 1966b),

AWSON and PRICE (1969), POST (1963, 1966a, 1966b) and for Liberia by

4SKENASY (1888, p. 39) also cited in FOX (1957).

A large proportion of the marine algae mentioned in this paper were collected

iuring a short visit to these two countries made between december 1971 and ja-

îuary 1972. Various other collections hâve also been located and these speci-

nens are also included.

^YSTEMATIC LIST

In this annotated list the généra are arranged alphabetically within the major

^roups and the species in their respectiv généra are also in alphabetical order.

ncluded under each species is information on its ecology, geographical distribu-

-ion in the Gulf of Guinea, presence and type of reproductive organs, as well as

iny points of spécial taxonomie interest. The terminology of LEWIS (1961) is

-ised when referring to the position of a plant on the shore whilst the four

k Department of Botany, University of Ghana, Legon, Ghana.

Rev. Algol, N. S., 1976, XI, 3-4 : 303-324.

Source : MNHN. Paris

304

D.M. JOHN

categories of exposure to wave action are used in a similar sense to those given

by LAWSON (1956). The place names of the collecting localities are taken from

MICHELIN map numbei 175 and are shown in figure 1. Ali the collections of

plants from Sassandra were made about 6 km to the west of the town at Baté-

lébré whilst the Canal de Vridi is just a few kilométrés from the center of Abid-

jan.

The largest number of specimens were collected by Mr. F. O. K. SEKU and

myself and for convenience our names are abbreviated as J & S. Examined also

were herbarium sheets of algae collected by Professor R. SOURIE (S) from Ivory

Coast and now deposited in the herbarium of Professor J. FELDMANN in Paris.

Another collection studied was one of dried material sent to us from the «Cen¬

tre O.R.S.T.O.M. d’Adiopodoumé» in Abidjan. Many of these sheets hâve more

than one collecting number and so each has also been given a new number

(6500 - 7500) when it has been incorporated into the phycological section of

the herbarium in the Botany Department, University of Ghana, Legon (GC).

These specimens were collected by the following persons whose names hâve been

abbreviated by the letters shown in brackets : Y. ATTIMS (A), F. BERNARD

(B), G. CREMERS (C), F. HALLE (H), C. HUTTEL (Hu) and P. DE RAHMS

(R). Finally some collections in spirit were kindly given to us by the «Départe¬

ment de Biologie, Université d’Abidjan», and were without the names of the

collectors. Whenever possible the number of each collection of a species is given

along with the name of the collector or collectors, the date and the locality it

camé from. Ail plants marked with an asterisk are species reported from this

part of the Guinea Coast for the first time.

The majority of the plants mentioned in this paper are deposited in the her¬

barium at the Botany Department of the University of Ghana, Legon whilst over

forty sheets are in Professor J. FELDAMNN’s herbarium in Paris. A number

of duplicates are also lodged in the cryptogamie herbarium at the British Mu¬

séum (Natural History), London.

CHLOROPHYTA

Bryopsis pennata Lamouroux

Occuring as soft and flaccid plants forming large patches particularly in mode-

rately wave-sheltered tidepools and on horizontal rock surfaces in the lower

eulittoral subzone.

Found at Cape Palmas (J & S., 6963, 6995, 2.1.72) in Liberia and Sassandra

(J & S., 6867, 30.12.71) and Fresco (S. 490, 491, 2-6.2.54) in Ivory Coast.

This plant has previously been reported in the Gulf of Guinea from Cameroun,

Dahomey, Ghana, Nigeria, Togo and the offshore island of Sao Tomé.

* Caulerpa taxifolia (Vahl) C. Agardh

Collected at Fresco (S., 2-6.2.54) in Ivory Coast by Pr. R. SOURIE but

without a number and with no accompanying ecological information. This

Source :MNHN, Paris

MARINE ALGAE OF IVORY COAST

305

plant is reported in the Gulf also from Ghana, Sao Tomé and with doubt from

Principe.

Chaetomorpha antennina (Bory) Kützing

As coarse and hair-like tufts growing in the upper part of the lower eulitto-

ral subzone on moderately wave-exposed rocks.

Collected at Cape Palmas (J & S., 6943, 6954, 2.1.72), Tabou (J & S., 6908,

1.1.72), Grand Bassam (7027, 17.11.61), Sassandra (A., 10, 6552, 12.12.66;

J & S., 6853, 30.1.72) and from Fresco (S., 2-6.2.54), known also from Came¬

roun, Ghana, Nigeria and Sao Tomé in the Gulf.

Chaetomorpha linum (O. F. Müller) Kützing

Found as a few filaments mixed in with other small algae growing in modera¬

tely wave-sheltered situations in the eulittoral zone.

Gathered at Cape Palmas (J & S., 6995, 2.1.72) and Sassandra (J & S., 6927,

30.12.71) being also reported in the Gulf of Guinea from Cameroun, Ghana (as

Chaetomorpha area) and Togo.

* Chaetomorpha nodosa Kützing

A few filaments found in amongst Cladophora plants collected at Grand

Lahou (C & H., 565, 7031, 12.2.67) and from a jetty in the Canal de Vridi near

Abidjan (S., 504, 27.1.54). Reported previously in the Gulf from Cameroun and

Togo.

Cladophora albida (Hudson) Kützing

Plants either growing as dense spongy tufts on the floor of shaded tidepools

n the littoral fringe or as larger looser tufts or mats in the lower part of the eu-

ittoral zone on wavecut platforms and especially abundant in brackish-water.

Found at Cape Palmas (J & S., 6954, 6969, 2.1.72) and with some doubt

rom Grand Lahou (C & H., 563 to 565, 6575 to 6578, 12.2.67), Fresco (A &

:., 20, 683, 6573, 12.7.67; S., 524, 2-6.2.54) and the Canal de Vridi (S. 504,

27.1.54). It has previously been reported along the Guinea Coast from Cameroun,

lhana, Nigeria and Togo.

'ladophora proliféra (Roth) Kützing

Growing as dark green and coarse cushion-like tufts on rocks and lithotham¬

nia in moderately sheltered to moderately wave-exposed situations in the lower

aulittoral subzone.

Collections from Cape Palmas (J & S., 6944, 6997, 2.1.72), Tabou (J & S.,

6906, 7009, 1.1.72), Sassandra (J & S., 6850, 30.12.71) and Fresco (S., 511,

2.-6.2.54) being previously reported in the Gulf from Ghana (as Cladophora

trichotoma ), Sao Tomé and with doubt from Cameroun and Gabon.

306

D. M. JOHN

* Cladophora vagabunda (Linnaeus) Van den Hoek

Occuring in amongst other algae usually growing on moderately wave-shelte-

red beach rocks in the lower part of the eulittoral zone.

Gathered at Sassandra (J & S., 6982, 30.12.71) and Fresco (S., 499, 512,

522, 2-6.2.54) and also known from Ghana (as Cladophora fascicularis), Nigeria

(as C. fascicularis ) and Togo.

* Codium guineense Silva

Forming bushy clumps in some abundance especially in wave-sheltered tide-

pools in the lower part of the eulittoral zone.

Found at Sassandra (J & S., 6879, 30.12.71) and Tabou (J & S., gametangia -

6898, 1.1.72) in Ivory Coast.

This plant appears to be common in various places along the West African

coast but has not as y et been validly published. For comments regarding the

status of this species refer to LAWSON and PRICE (1969).

* Enteromorpha clathrata (Roth) Greville

Collections of this plant hâve been made in Ivory Coast at Fresco (A& C., 167,

679, 6736, 12.7.67) and Grand Lahou (C & H., 566, 6572, 12.2.67) and it is

also known in the Gulf from Cameroun (unpublished), Ghana, Nigeria, Sao

Tomé and Togo.

Enteromorpha flexuosa (Wulfen ex Roth) J. Agardh

Subspecies flexuosa J. Agardh

Growing in brackish-water conditions often mixed with Cladophora, or on

moderately wave-sheltered beach rocks in the upper eulittoral subzone; occasio-

nally as low mats on stranded logs and then in the littoral fringe.

Gathered at Sassandra (J & S., 6983, 6987, 29.12.71), Grand Bassam (7027,

17.11.61), Canal de Vridi (S., 506, 504, 27.1.54) and a few fragments found in a

collection from Cape Palmas (J & S., 6964, 2.1.72). This species has also been

reported in the Gulf from Cameroun (as Enteromorpha compressa), Ghana, Ni¬

geria, Sao Tomé and Togo.

Rhizoclonium africanum Kützing

Filaments usually entangled with small red algae growing in cracks, crevices or

beneath rock overhangs, or on the underside of logs in the littoral fringe and

especially in brackish-water situations.

Collections made at Tabou (J & S., 6979, 6890, 6981, 1.1.72), Sassandra (J &

S., 6988, 29.12.71) and also on mangroves at Azuretti (A, C & H., 567, 6563,

14.2.67) which is near to Grand Bassam. Known in the Gulf of Guinea from

Cameroun (unpublished) and Ghana (as Rhizoclonium hookeri ).

* Rhizoclonium riparium (Roth) Harvey

Occurring on «Plateforme d’abrasion au niveau de la basse mer de vive eau» at

Fresco (S., 524, 2-6.2.54) according to the label on the specimen. Found in the

Gulf also in Cameroun, Ghana and Togo.

Source : MNHN, Paris

MARINE ALGAE OF IVORY COAST

307

* Siphonocladus brachyartus Svedelius ?

Growing as dense, spongy, cushion-like tufts or as a springy «turf» on nearly

horizontal rocks in the eulittoral zone and extending into the littoral fringe

beneath rock overhangs and in shaded tidepools at the entrance to the Tabou

River (J & S., 6894, 1.1.72).

This plant was originally reported to be a Valoniopsis (JOHN 1972) but on

further considération it seems to be closely related to Siphonocladus brachyartus

described by SVEDELIUS (1895) from the Magellan Straits in South America.

It resembles this species in the dimensions of the cells of the branches and the

branching pattern. In both plants longitudinal division in the branches is very

rare and there are often cross-walls associated with the side branches. In fact, the

only important différence between this genus and Valoniopsis is in the form and

development of the branching which in the case of the latter genus is fully

described and illustrated by B0RGESEN (1934). The Ivorian and South Ame¬

rican plants are very similar not only in form but are found in similar habitats,

nevertheless, the identification of the West African material is still considered

with some doubt. The main reason for this doubt is the wide disparity in climate

between the two régions with the Magellan Straits having arctic-boreal condi¬

tions. Unfortunately attempts to trace the type material of Siphonocladus

brachyartus hâve so far been unsuccessful; correspondence with the curator of the

Uppsala Muséum (UPS) has revealed thç possibility that the collection might

hâve been lost.

Struvea anastomosans (Harvey) Piccone et Grunow

Occuring as semi-prostrate clumps in the «algal turf» growing on moderately

wave-sheltered rocks in the lower eulittoral subzone.

Found at Sassandra (J & S., 6924, 30.12.71) and Fresco (S., 519, 2-6.2.54)

in Ivory Coast and previously reported in the Gulf of Guinea from Cameroun,

Gabon, Ghana and Sao Tomé.

Ulva fasciata Delile

Occuring most commonly in moderately sheltered to moderately wave-

exposed tidepools in the lower eulittoral subzone.

Collections from Cape Palmas (J & S., 6996, 6945, 2.1.72) and Grand Bassam

(7012, 17.11.63) in Ivory Coast and previously known from Ghana and Sao

Tomé.

Ulva lactuca Linnaeus

As dense mats growing over logs in the littoral fringe being associated with a

good deal of sand or as small solitary plants on larger algae in the «turf» found

in the lower eulittoral subzone.

Gathered at Cape Palmas (J & S., 6999, 2.1.71, 6849, 30.12.71) whilst re-

corded also from Dahomey, Ghana, Principe, Sao Tomé and Togo.

* Ulva rigida C. Agardh

Growing on logs in the littoral fringe at Sassandra (J & S., 6875, 30.12.71;

A., 13, 6534, 12.12.66) and Fresco (S., 2-6.2.54) and known previously in the

Gulf of Guinea only from Ghana.

308

D. M. JOHN

PHAEOPHYTA

Bachelotia antillarum (Grunow) Gerloff

Forming small soft tufts or more usually as extensive mats growing on mode-

rately wave-sheltered rocks in the upper eulittoral subzone, often associated with

a good deal of sand when found on beach rocks.

Collected at Cape Palmas (J & S., plurilocular sporangia - 6937, 2.1.72) and

Sassandra (J & S., 6923, 6927, 30.12.72) and also reported from Ghana, Nigeria

and Sao Tomé.

* Basispora africana John et Lawson

As black and often very slippery expansions over moderately sheltered to

moderately wave-exposed rocks, sometimes in the form of coalescing rings,

growing just above the lithothamnia subzone.

Collected at Sassandra (J & S., unilocular sporangia - 6860, 2.1.72), Tabou

(J & S., unilocular sporangia - 6929, 1.1.72) and Cape Palmas (J & S., 6932,

unilocular sporangia - 6873, 2.1.72).

Chnoospora minima (Hering) Papenfuss

Growing as coarse clumps in the lower part of the upper eulittoral subzone on

moderately wave-exposed rocks.

Found at Cape Palmas (J & S., 6938, 2.1.72) and Fresco (A & C., plurilocular

sporangia - 24, - 687, 6565, 12.7.67) whilst also known from Dahomey, Ghana,

Nigeria, Sao Tomé and Togo.

Colpomenia sinuosa (Roth) Derbès et Solier

Plants to about 2 cm across and growing on larger algae in moderately wave-

sheltered situations in the lower subzone of the eulittoral.

Gathered only from Sassandra (J & S., 6881, 30.12.71) in Ivory Coast and

elsewhere in the Gulf known from Ghana, Togo and Sao Tomé.

Dictyopteris delicatula Lamouroux

Occuring as dense low mats on moderately wave-sheltered rocks and forming

small and compact clumps in more wave-exposed situations in the sublittoral

fringe and in tidepools at higher levels on the shor'e.

Collected at Cape Palmas (J & S., 6939, 2.1.72) and Sassandra (A., 1, 6551,

12.12.66; J. & S., 6858, 30.12.71, 6990, 29.12.71) and in other parts of the

Gulf of Guinea known from Ghana and Nigeria.

* Dictyota bartayresii Lamouroux

A few small plants found growing in moderately wave-sheltered tidepools.

Found only at Cape Palmas (J 6c S., 6953, 2.1.72) in Liberia and also repor¬

ted from Cameroun, Ghana, Principe and Sao Tomé.

Source : MNHN. Paris

MARINE ALGAE OF IVORY COAST

309

* Dictyota cervicomis Kützing

Form curvula Taylor

Found on «rochers de Tabou» (B, C, Hu & R., 583, 6557, ?.2.67) in Ivory

Coast and unpublished records for this plant exist for both Ghana and Sao

Tomé.

Dictyota ciliolata Kützing

Growing as bushy clumps on moderately wave-sheltered rocks in tidepools in

the lower eulittoral subzone.

Collections from Sassandra (J & S., oogonia and sporangia - 6885, - 6889,

31.12.71) and Tabou (B, C, Hu & R., 583, 6559, sporangia - 585, 6561, ?.2.67)

being known also in the Gulf from Ghana, Nigeria and Sao Tomé.

Ail Ivory Coast plants were somewhat unusual in having wide concentric

bands of alternating lighter and darker brown on dried specimens with the

darker ones being irridescent in freshly collected material.

* Dictyota dichotoma (Hudson) Lamouroux ?

A few small and immature plants found growing on wave-cut platforms or as

an epiphyte on a species of Laurencia in a moderately wave-sheltered tidepool.

Found at Sassandra (J & S., 6973, 30.12.71) and Fresco (S., 517, 518, 2-6.

2.54) and known from Sao Tomé and Principe and with doubt from Ghana (un¬

published) and Togo.

This record is given here with some réservation as the possibility does exist

that these plants from Ivory Coast are just immature forms of some of the other

Dictyota species mentioned above.

Ectocarpus breviarticulatus J. Agardh

As rope-like tufts on rocks and occasionally as an epiphyte on Chnoospora

growing on moderately wave-exposed rocks in the upper eulittoral subzone.

Collected at Cape Palmas (J & S., plurilocular sporangia - 6940, - 6938,

2.1.72) Monogaga (C., 531, 6568, 1.1.76) and Fresco (A. & C., 22: 685, 6566,

12.7.67) being reported in the Gulf also from Dahomey, Ghana, Nigeria and

Togo.

* Ectocarpus rhodochortonoides Bôrgesen

Growing on Gracilaria dentata in the lower eulittoral subzone on moderately

wave-exposed rocks.

Gathered near Sassandra (J & S., plurilocular sporangia - 6991, 29.12.71) in

Ivory Coast and also known from Ghana.

* Giffordia rallsiae (Vickers) Taylor

Forming small globose tufts on rocks and Siphonaria shells in moderatly

wave-exposed situations in the upper part of the eulittoral zone.

Found at Cape Palmas (J & S., plurilocular sporangia - 7005, 2.1.72) in Libe-

310

D. M. JOHN

ria and also reported in the Gulf of Guinea from Dahomey, Ghana and Togo.

Giffordia sp.

A few stérile plants in which the chloroplasts were contracted or occasionally

discernable as a number of dises hâve been collected at Fresco (A & C., 20, 683,

6573, 12.7.67).

Lobophora variegata (Lamouroux) Womersley

The prostrate form of this species has been found growing in moderately

wave-exposed tidepools in the eulittoral zone.

A single collection from Cape Palmas (J & S., 6960, 2.1.72) and previously

recorded in the Gulf of Guinea as Pocockiella variegata from Principe, Came¬

roun and Ghana.

* Padina australis Hauck ?

A few small plants collected from «Plateforme d’abrasion au niveau de la

basse mer de vive eau, peu abondant.» at Fresco (S., sporangia - 520, 2-6.2.54) in

Ivory Coast and also known from Cameroun (as Padina gymnospora).

This détermination must be regarded with some doubt since the plants are

small and rather fragmented though the thickness of the thallus does vary from

two cells at the margin to four below and the hair zones are very indistinct.

Padina tetrastromatica Hauck

Growing as small patches on moderately wave-sheltered rocks in the lower

eulittoral subzone and often abundant and as large plants when in shallow tide¬

pools.

Gathered at Sassandra (J & S., 6878, 30.12.71) and Tabou (J & S., 6903,

1.1.72) and in the Gulf also known from Ghana and Togo.

Padina vickersiae Hoyt

Occuring as variously sized patches on moderately wave-sheltered rocks in the

lower eulittoral tidepools and usually associated with Sargassum.

Collections from Cape Palmas (J. & S., 6904, 6947, 2.1.72), Tabou (B, C,

Hu & R., 581, 6570, ?.2.67) and near Sassandra (J 6c S., sporangia - 6880, 30.

12.71) and also known in the Gulf from Cameroun, Sao Tomé and Principe.

Ralfsia expansa (J. Agardh) J. Agardh

As crusts covering moderately sheltered to moderately wave-exposed rocks in

the lower eulittoral subzone and at higher levels in rocky tidepools.

Found at Cape Palmas (J & S., 6962, 2.1.72) and Sassandra (J & S., 6873,

6859, 30.1.71) and reported also from Cameroun, Dahomey, Ghana and Togo.

Sargassum vulgare C. Agardh

Occuring in abundance in shallow rocky tidepools and présent on open rocks

Source :MNHN. Paris

MARINE ALGAE OF IVORY COAST

311

except where wave action is severe, usually defines the upper limit of the sub¬

littoral fringe.

Found at Cape Palmas (J & S., 6948, 2.1.72) and Sassandra (J & S., 6857,

6948, 30.12.71; A., 8, 6538, 12.12.66) and known from ail countries bordering

the Gulf of Guinea from which collections hâve been made.

* Sphacelaria furcigera Kützing

It has only been found as propagules trapped in the «algal turf» collected

from Cape Palmas (J & S., 7006, 2.1.72) and Sassandra (J & S., 6888, 30.12.71)

and previously reported from Dahomey, Ghana and Cameroun.

Sphacelaria tribuloides Meneghini

Forming small cushion-like tufts on moderately wave-exposed rocks and Si-

phonaria shells in the upper eulittoral subzone.

Collected at Cape Palmas (J & S., propagules - 6958, - 7004, 2.1.72) and also

known in the Gulf from Ghana and Togo.

RHODOPHYTA

Amphiroa beauvoisii Lamouroux

Growing on moderately wave-exposed rocks in the lower eulittoral subzone.

Collected in Ivory Coast only from Sassandra (J & S., 6864, 30.12.71) and

recently also reported from Ghana.

Amphiroa peruana Areschoug

Forming semi-prostrate clumps in the lower eulittoral subzone on moderatly

sheltered to moderatly wave-exposed rocks.

Found at Sassandra (J & S., 6884, 30.12.71) and Cape Palmas (J & S., 6773,

2.1.72) and previously reported from Ghana.

* Audouinella dasyae (Collins) Woelkerling

As a fine felty layer over the foliar appendages of Sargassum vulgare growing

in moderately wave-sheltered tidepools in the eulittoral zone.

Found in a collection from Cape Palmas (J & S., monosporangia - 6948, 2.1.

72) and known also from Ghana.

* Audouinella daviesii (Dillwyn) Woelkerling

Occuring as tufts to about 1 mm in height on the upper parts of the filaments

of Chaetomorpha antennina growing on moderately wave-exposed rocks.

Plants bearing monosporangia found on Chaetomorpha collected at three

localities - Cape Palmas (J & S., 6943, 2.1.72), Tabou (J & S., 6908, 1.1.72) and

Grand Bassam (7027, 17.11.63). This is the first report of this plant from the

Guinea Coast though in West Africa it is also known from the Canary Islands.

312

D. M. JOHN

Bostrychia calliptera Montagne

Growing on moderately wave-sheltered rocks together with other small red

algae such as Caloglossa in the littoral fringe at the entrance to the Tabou

River.

Collected at Tabou (J & S., 6890, 1.1.72) having previously been recorded in

the Gulf of Guinea from Ghana.

Bostrychia radicans Montagne

Form hapteromanica Post

Found together with other species of red algae growing in the littoral fringe

at the entrance to the Tabou River.

This form, only collected at Tabou (J & S., 6890, 6893, 6891, 1.1.72) in

Ivory Coast, has previously been reported from Cameroun though the species

is also known in the Gulf from Cameroun, Ghana, Nigeria and Sao Tomé.

Bryocladia thyrsigera (J. Agardh) Schmitz

Occuring most commonly as loose mats growing on moderately sheltered to

moderately wave-exposed beach rocks which are gently sloping and sand-scou-

red, occasionally mixed with the «algal turf» in the lower part of the eulittoral

zone.

Found at Cape Palmas (J & S., 6935, 2.1.72), Sassandra (J & S., tetrasporan-

gia - 6975, 30.12.71), Tabou (J & S., 6909, 1.1.72) and Fresco (A & C., 15, 678,

12.7.67, tetrasporangia and cystocarps - 6558, 12.7.67; S., 478, 2-6.2.54) in

Ivory Coast having previously been recorded in the Gulf from Ghana, Nigeria

and Togo.

*Callithamniella tingitana (Schousboe ex Bornet) Feldmann-Mazoyer

Growing as a few stérile filaments mixed with a fine Polysiphonia on the

floor of a moderately wave-sheltered tidepool in the upper eulittoral subzone.

Gathered at Cape Palmas (J & S., 6961, 2.1.72) in Liberia and also found in

Ghana (unpublished).

* Callithamnion sp.

A plant believed to be referable to this genus was found as an epiphyte on

Gracilaria dentata growing in sheltered situations on rocks in the lower part of

the eulittoral zone.

Found at Tabou (J & S., 7007, tetrasporangia - 7008, 1.1.72) in Ivory Coast

whilst no published records exist for this genus in the Gulf of Guinea.

Caloglossa leprieurii (Montagne) J. Agardh

Occuring as semi-prostrate clumps in cracks, crevices and beneath rock over-

hangs in the littoral fringe, and in the «turf» of green algae in the eulittoral zone

within the entrance of the Tabou River.

Collected only at Tabou (J & S., 6880, 6889, tetrasporangia - 6981, 1.1.72)

Source : MNHN, Paris

MARINE ALGAE OF IVORY COAST

313

in Ivory Coast and known previously in the Gulf from Cameroun, Ghana and

Nigeria.

Caloglossa ogasawaraensis Okamura

Found in the same situations as Caloglossa leprieurii in the entrance to the

Tabou River (J & S., 6981, 1.1.72) and also reported in the Gulf from the off¬

shore island of Sao Tomé.

Catenella impudica (Montagne) J. Agardh

On wave-sheltered rocks in the littoral fringe at the entrance to the Tabou

River (J & S., 6890, 6981, 1.1.72) and known also from Cameroun in the Gulf.

Centroceras clavulatum (C. Agardh) Montagne

A common alga at most localities either growing in the «algal turf» on mode-

rately wave-exposed rocks or as small and often bleached tufts in the upper

eulittoral subzone in more wave-exposed situations.

Collected at Tabou (B, C, Hu & R., 587, 6562, ?.2.67; J & S., 6910, 1.1.72),

Fresco (A & C., 17, 680, 6567, 12.7.67; S., 514, tetrasporangia - 494, 2-6.2.54)

and Sassandra (A., 2, 6550, tetrasporangia - 3, 6539, 12.12.66; J & S., 6845,

30.12.71) in Ivory Coast and Cape Palmas (J & S., 6941, tetrasporangia - 6968,

2.1.72) in Liberia. Occurs in other parts of the Gulf of Guinea in Ghana, Nigeria,

Cameroun, Togo, Dahomey and the offshore island of Sao Tomé.

* Ceramium ledermanni Pilger

Growing on larger algae in moderately sheltered to moderately wave-exposed

situations.

Found at Cape Palmas (J & S., on Grateloupia doryphora, carposporangia and

tetrasporangia - 6980, - 6955, 2.1.72) and Tabou (J & S., on Gracilaria dentata,

tetrasporangia - 7008, 1.1.72) and previously only known in the Gulf from Ca¬

meroun from where it was fïrst described.

* Ceramium tenuissimum (Roth) J. Agardh

According to the label accompanying the specimens collected from Fresco

(S., tetrasporangia - 513, - 514, - 515, 2-6.2.54) it was found on «Plateforme

d’abrasion au niveau de la basse mer de vive eau.». This species has previously

been only reported in the Gulf of Guinea from Cameroun.

Ceramium sp.

A few small fragments of a plant belonging to this genus were found together

with filaments of Platysiphonia growing in a moderately wave-sheltered tidepool

at Tabou (J & S., tetrasporangia - 6914, 1.1.72). The fragments were insufficient

to make possible a positive détermination.

Source :MNHN. Paris

314

D. M. JOHN

* Champia parvula (C. Agardh) Harvey

A single collection made at Fresco (S., tetrasporangia - 513, 2-6.2.54) growing

in the same situation as Ceramium tenuissimum. Reported in the Gulf also from

Cameroun and the islands of Sao Tomé and Principe.

Coraïlina pilulifera Postels et Ruprect

Occuring as large clumps or occasionally as extensive mats growing over the

lithothamnia subzone of the eulittoral, particularly abundant on gently sloping

surfaces subject to current or wave surge and in the overflow channels of tide-

pools.

Found at Sassandra (J & S., 6846, 6907, 30.12.71) and Cape Palmas (J & S.,

6772, 2.1.72) and having previously been reported from Ghana.

Cryptonemia luxurians (C. Agardh) J. Agardh

Growing usually in moderately wave-sheltered tidepools in the lower part of

the eulittoral zone.

Collected at Sassandra (J & S., 6921, 30.12.71) and Fresco (S., 477, 2-6.2.

54) and also reported from Ghana as Cryptonemia seminervis.

This species and Cryptonemia seminervis are very closely related with both

having a partial midrib présent but C. luxurians has the tetrasporangial sori

confined to marginal «leaflets» and not scattered over the frond. This distinc¬

tion between these two species is a doubtful one and it remains to be seen whe-

ther these plants are really not conspecifïc.

* Erythrocladia irregularis Rosenvinge

Forming minute dises on the surface of larger algae growing in moderately

wave-exposed situations in the eulittoral zone as well as in tidepools and brackish-

water habitats.

Occurs at Cape Palmas on Sargassum (J & S., 6948, 2.1.72), Chnoospora

(J & S., 6968, 2.1.72), Laurencia intermedia (J & S., 6968, 2.1.72) and Chae-

tomorpha antennina (J & S., 6943, 2.1.72), also on this latter species at Tabou

(J & S., 6908, 1.1.72) and Grand Bassam (7027, 17.11.61) whilst at Fresco

found on Struvea anastomosans (S., 519, 2-6.2.54) and Rhizoclonium riparium

(S., 524, 2-6.2.54). In other parts it has been reported as Erythrocladia subinte¬

gra from Ghana and Nigeria.

* Erythrotrichia carnea (Dillwyn) J. Agardh

Occuring as soütary plants on larger algae growing in moderately wave-shelte¬

red tidepools in the lower eulittoral subzone.

Collected at Cape Palmas growing on Laurencia tenera (J & S., 6951, 2.1.72)

and Padina vickersiae (J & S., 6947, 2.1.72) and recorded in the Gulf also from

Dahomey, Ghana and Togo.

Source : MNHN. Paris

MARINE ALGAE OF IVORY COAST

315

Galaxaura marginata (Ellis et Solander) Lamouroux

As solitary individuals occuring on moderately wave-sheltered rocks, espe-

cially abundant in lower eulittoral tidepools.

Collections obtained from Sassandra (J & S., 6983, 6932, 30.12.71) and

Tabou (B, C., 586, Hu & R., 6560, ?.2.67; J & S., 6902, 1.1.72) and also known

from Cameroun, Gabon (as Brachytrichia australis) and the islands of Sao Tomé

and Principe.

* Galaxaura oblongata (Ellis et Solander) Lamouroux

Growing in some abundance in the lower part of the eulittoral on modera-

tely-sheltered rocks, often found in tidepools.

Plants found at Tabou (J & S., 6900, 1.1.72) and Fresco (S., cystocarps - 487,

2-6.2.54) and known in the Gulf also from Gabon (as Galaxaura fragilis), Sao

Tomé (as Galaxaura cylindrica), Ghana and Principe.

Galaxaura rugosa (Ellis et Solander) Lamouroux

According to the label accompanying the specimen it was collected on «ro¬

chers de Tabou» (B, C, Hu & R., cystocarps - 584, 6534, ?.2.67); this plant has

previously been reported in the Gulf from both Cameroun and Sao Tomé.

* Gelidiopsis variabilis (J. Agardh) Schmitz

Occuring in moderately sheltered to moderately wave-exposed situations as

oarse and erect clumps growing in the upper part of the lithothamnia subzone,

«pecially abundant in tidepools.

Found at Tabou (J & S., 6901, 1.1.72) and Sassandra (J & S., 6887, 30.12.

'1) in Ivory Coast and also known from Ghana, Cameroun and Sao Tomé.

jélidium corneum (Hudson) Lamouroux

As bushy clumps in the lower eulittoral subzone on moderately wave-exposed

it Cape Palmas (J & S., 7003, tetrasporangia - 6998, 2.1.72) and has previously

;een reported from Liberia as Gelidium arbuscula. It has previously been repor-

ed in the Gulf of Guinea from Togo (as Gelidium arbuscula ), Nigeria (as Geli-

lium pusillum) and is known from Ghana (unpublished).

There is some confusion regarding the typification of this species since the

niginal description of this plant was based on material now known to be refera-

>le to Gelidium sesquipedale (DIXON, 1967).

' Gelidium elminense Dickinson

According to the label with this specimen from Fresco (S., tetrasporangia -

182, 2-6.2.54) it was found at «Niveau inférieur des marées, abondant.» and the

Dnly previous report of this plant from the Gulf is from the type locality at El-

nina, Ghana.

This plant has the main axes terete except for near the branch tips whilst

oranches often arise opposite to one another and give the uppermost branches a

316

D. M. JOHN

trifïd appearance. This species might be regarded as falling into the Gelidium cri-

nale complex as defined by DIXON (1958, 1966) in his révision of the European

représentatives of this genus.

Gelidium pusillum (Stackhouse) Le Jolis

Plants readily referable to this species usually occuring as low ring-like pat-

ches growing on moderately sheltered to moderately wave-exposed rocks and

lithothamnia in the lower eulittoral subzone. Larger plants from 1-2 cm in

height and forming dense cushion-like tufts or mats on moderately wave-shel-

tered granité boulders may be considered to be a variety of this species.

This species (J & S., 6933, 2.1.71) and the variety pulvinatum (C. Agarth)

J. Feldmann (J & S., 6949, 7030, 2.1.71) were found at Cape Palmas in Liberia.

The variety bears a close resemblance to Gelidium foliosum described by

DANGEARD (1951) from Sénégal. He points out the close relationship between

his new plant and Gelidium pusillum var. pulvinatum stating it to be «...plus

développé plus luxuriant.» Gelidium reptans, which has been reported from Sao

Tomé, was considered by B0RGESEN (1943) to be referable to this variety of

Gelidium pusillum though it had earlier been given spécifie rank by KYLIN

(1938). It seems unwarranted at the présent time to afford spécifie rank to

plants if there is any doubt regarding their spécifie status until a global re-apprai-

sal has been made of this extremely polymorphie genus. The species has been re¬

ported in the Gulf of Guinea also from Cameroun, Dahomey, Togo, Ghana (un-

published) as well as from Sao Tomé (as Gelidium reptans).

Gracilaria dentata J. Agardh

Forming extensive patches on moderately wave-sheltered rocks and as smaller

clumps in more wave-exposed situations, usually found in the lower eulittoral

subzone and very abundant in large tidepools.

Found at Cape Palmas (J & S., cystocarps - 6936, 2.1.72), Sassandra (J & S.,

6919, 30.12.71; A., cystocarps - 9, 6542, 12.12.66;cystocarps - 7025, 12.4.60)

and Fresco (S., tetrasporangia, cystocarps - 483, 2-6.2.54). Reported in the Gulf

of Guinea previously from Cameroun, Ghana, Nigeria and Sao Tomé.

Gracilaria disputabilis (Bodard) Bodard

According to the label on the specimens from Fresco (S., ?485, cystocarps -

484, 2-6.2.54) found at «Niveau inférieur des marées, dominant sur rocher ho¬

rizontal.» and is also known in the Gulf only from Ghana (unpublished).

Gracilaria verrucosa (Hudson) Papenfuss

A few solitary individuals growing in the «alga turf» in the lower eulittoral

subzone on moderately sheltered rocks.

Collected at Sassandra (J & S., cystocarps - 6985, - 6869, 30.12.71) and also

reported from Cameroun, Ghana, Togo and Sao Tomé.

Source : MNHN, Paris

MARINE ALGAE OF IVORY COAST

317

Gracilaria sp.

A few small plants collected on «Plateforme d’abrasion au niveau de la basse

mer de vive eau, rare.» at Fresco (S., tetrasporangia - 526, 2-6.2.54). The flatte-

ned nature of the fronds and the branching is suggestive of Gracilaria foliifera.

Grateloupia doryphora (Montagne) Howe

Occuring as widely dispersed plants on rocks and barnacles in moderately

sheltered to moderately wave-exposed situations in the eulittoral zone.

Found in the Canal de Vridi near Abidjan (S., cystocarps - 509, 27.1.54, te¬

trasporangia - 475, 2-6.2.54), Sassandra (J & S., 6855, 30.12.71; A., 7, 6535, 12.

12.66) and Cape Palmas (J & S., 6955, 2.1.72) being previously reported in the

Gulf from Ghana as Grateloupia gibbesi.

Grateloupia filicina (Lamouroux) C. Agardh

Growing in the eulittoral zone in greatest abundance in moderately wave-shel-

tered situations as loose mats on sand-scoured rocks or where there is freshwater

nfluence, forming only small coarse clumps in very wave-exposed places.

Collected at Tabou (J & S., 6897, 1.1.72), Sassandra (J & S., 6854, 30.12.

71), Fresco (A & C., 21, 684, 6569, 12.7.67; S., 479, 480, 2-6.2.54) and at a

etty in the Canal de Vridi near Abidjan (S., 505, 27.1.54). Known in the Gulf

lso from Cameroun, Dahomey, Ghana, Nigeria and Togo.

",riffithsia schousboei Montagne

Occuring as bright red and globose tufts on larger algae such as Amphiroa,

'■elidiopsis and Corallina growing in moderately sheltered to moderately wave-

xposed situations in the lower part of the eulittoral subzone.

Found at Sassandra (J & S., tetrasporangia - 6870, 30.12.71) and Tabou

J & S., spermatangia - 7006, 1.1.72) and recently reported from Ghana.

Gymnogongrus nigricans Dangeard ?

A few small plants drying almost black hâve been collected near Sassandra

A., 4, 6541, 12.12.66) in Ivory Coast whilst elsewhere in the Gulf of Guinea

is known from Cameroun, Dahomey and Ghana.

Gymnogongrus tenuis (J. Agardh) J. Agardh

Plants having flattened branches becoming somewhat attenuate towards the

ips were gathered on rocks at Fresco (A & C., 18, 681, 6555, 12.7.67; S.,

99, 2-6.2.54) and this species has also been reported from Nigeria.

gymnogongrus spp.

a - — Plants having terete and not noticeably fastigiate branches were collected

t Fresco (A & C., 277, 6564, 12.7.67; S., 481, 2-6.2.54) and Cape Palmas (J &

,6952, 2.1.72).

b. — A larger and more robust plant having flattened branches with acute tips

318

D.M. JOHN

was found as dense clumps on moderately wave-exposed rocks at Tabou (J & S.,

6912, 1.1.72) and Sassandra (J & S., 6922, 30.12.71). It is not inconceivable

that this might be no more than a form of Gymnogongrus tenuis.

Herposiphonia densa Pilger

Growing as low ring-like patches on moderately wave-exposed rocks and li¬

thothamnia in the lower eulittoral subzone though in less exposed situations

found often in the «algal turf».

Found at Cape Palmas (J & S., tetrasporangia - 6931, 2.1.72), Tabou (J & S.,

6915, 1.1.72) and Sassandra (J & S., 6844, 6856, 30.12.71) being also reported

in the Gulf from Cameroun, Ghana and Togo.

* Herposiphonia tenella (C. Agardh) Ambronn

Forming small and felty circular or ring-like patches on moderately wave-

exposed rocks or lithothamnia in the lower part of the eulittoral zone.

Gathered only on one occasion at Cape Palmas (J & S., 6994, 2.1.72) in

Liberia but common in Ghana though not reported from any other countries

bordering the Gulf of Guinea.

* Hildenbrandia prototypus Nardo

Occuring as dark red patches covering often large areas of rock in the upper

eulittoral subzone where exposure to wave action is moderate.

Collected at Tabou (J & S., 6928, 1.1.72) and Sassandra (J & S., 6886, 30.

12.71) in Ivory Coast and Cape Palmas (J. & S., tetrasporangia - 6984, 2.1.72)

in Liberia whilst previously reported from Sao Tomé (as Hildenbrandia rosea)

and Ghana.

* Hypnea cervicomis J. Agardh

As intricate cushion-like clumps growing on moderately wave-exposed rocks

in the lower part of the eulittoral zone.

Found only at Cape Palmas (J & S., 6950, 6958, 2.1.72) but reported in the

Gulf also from Ghana and both the islands of Principe and Sao Tomé.

Hypnea musciformis (Wulfen) Lamouroux

Growing as loose clumps or else forming part of the «algal turf» on moderate¬

ly sheltered to moderately wave-exposed rocks in the lower eulittoral subzone.

Gathered at Cape Palmas (J & S., tetrasporangia - 6956, 2.1.72), Tabou (J &

S., 6911, 1.1.72) and near Sassandra (J & S., 6975, 30.12.71; A., 11, 6536, 12.

12.66), also known in the Gulf from Cameroun, Ghana, Nigeria, Togo, Sao

Tomé and Principe.

* Jania crassa Lamouroux

Forming small clumps on moderately wave-exposed rocks and as more exten¬

sive patches in moderately wave-sheltered tidepools or on sand-scoured beach

Source : MNHN. Paris

MARINE ALGAE OF IVORY COAST

319

rocks in the lower part of the eulittoral zone.

Found in Ivory Coast at Tabou (J & S., 6905, 7010, 1.1.72), Fresco (S., 488,

2-6.2.54) and Sassandra (J & S., 6865, 6989, 30.12.71 ; A., 12, 6537, 12.12.66)

whilst in other parts of the Gulf it has been reported from Ghana and Gabon as

Jania natalensis.

Jania fastigiata Harvey

Growing in the «algal turf» or over larger algae and is in greatest abundance in

moderately wave-sheltered situations in the eulittoral zone.

Gathered at Sassandra (J & S., 6882, 30.12.71) and as a few small and rather

fragmentary plants at Cape Palmas (J & S., 6953, 6971, 7002, 2.1.72) being

previously only known in the Gulf from Ghana.

* Lasiothalia sp.

As a small epiphyte growing on larger algae in a moderately wave-sheltered

tidepool at Cape Palmas (J & S., carposporangia - 7000, 2.1.72) and as a few

filaments in a collection from Tabou (J & S., 7008, 1.1.72),

This material was identified by Dr. E. WOLLASTON who was not able to

give it spécifie rank until a révision of this little known genus is completed. This

genus has not previously been reported from West Africa though it is conceivable

that it might in the past hâve been confused with the closely related Callitham-

nion.

* Laurencia galtsoffi Howe

Occuring as erect clumps growing on moderately wave-exposed rocks in the

lower part of the eulittoral zone only at Cape Palmas (J & S., 6930, 2.1.72) in

Liberia and recently recorded from Ghana.

* Laurencia intermedia Yamada

Fonping coarse and usually reddish-purple clumps on moderately wave-expo-

sed rocks in the lower eulittoral subzone.

Collected both at Cape Palmas (J & S., 6774, 6993, 2.1.72) and Sassandra

(J & S., 6863, 30.12.71) whilst elsewhere in the Gulf of Guinea it is only known

from Ghana where it is the most common Laurencia species.

* Laurencia nidifica J. Agardh ?

Just a few fragments hâve been collected from Sassandra (A., tetrasporangia -

3, 6540, 12.2.66) and these are insufficient to make an absolutely positive déter¬

mination. This species has previously been reported in the Gulf from Ghana.

* Laurencia tenera Tseng

Growing usually as low clumps or more extensive spongy mats and only very

rarely epiphytic, particularly common in moderately wave-sheltered tidepools

but occasionally in wave-exposed situations.

Source :MNHN, Paris

320

D.M. JOHN

Found at Cape Palmas (J & S., tetrasporangia - 6951, 2.1.72), Sassandra

(J & S., 6888, 30.12.71) and Fresco (S., cystocarps - 487, 2-6.2.54) whilst also

reported from Ghana and Togo.

Lophosiphonia reptabunda (Suhr) Kylin

Occuring as tufts or forming extensive mats mixed with other small algae in

cracks, crevices and beneath rock overhangs, occasionally on the lower surface

and the eut ends of stranded logs; grows in the upper eulittoral subzone though

most commonly to be found in the littoral fringe.

Collected at Fresco (S., cystocarps and tetrasporangia - 493, 2-6.2.54) and

Sassandra (J & S., 6987, tetrasporangia - 6976, 29.12.71) in Ivory Coast and

known in the Gulf also from Cameroun and Ghana as Lophosiphonia obscura.

*Peyssonnelia polymorpha (Zanardini) Schmitz

Forming dark reddish-brown crusts in the lower part of the eulittoral zone

growing over moderately wave-exposed rocks.

Found only at Sassandra (J & S., tetrasporangia - 6883, 30.12.71) in Ivory

Coast having not been reported from elsewhere in the Gulf of Guinea.

Platysiphonia miniata (C. Agardh) Bôrgesen

As soft filamentous tufts, often mixed with other algae, growing on modera¬

tely wave-sheltered rocks in the lower eulittoral subzone or as small patches on

the floor of shallow and wave-sheltered tidepools.

Collected at Tabou (J & S., 7008, tetrasporangia - 6914, 1.1.72), Sassandra

(J & S., 6917, tetrasporangia - 6925, - 6990, 1.1.72) and Fresco (S., tetraspo¬

rangia - 492, 2-6.2.54) having been previously reported in the Gulf only from

Ghana.

Polysiphonia ferulacea Suhr ex J. Agardh

Growing as hair-like tufts or low mats both on rocks and large barnacles ( Ba-

lanus tintinnabulum) in the lower eulittoral subzone in moderately wave-expo-

sed situations or in the «algal turf» in places where the wave action is less.

Gathered at Cape Palmas (J & S., 6943, tetrasporangia - 6942, - 6966, - 7001,

2.1.72), Sassandra (J & S., 6856, 30.12.71) and Fresco (S., cystocarps and te¬

trasporangia - 489, 2-6.2.54) having previously been reported both from Nigeria

and Ghana.

Polysiphonia sp.

As tufts of fine filaments growing on moderately wave-sheltered rocks and

sometimes in tidepools in the lower part of the eulittoral zone at Sassandra

(J & S., tetrasporangia - 6844, 30.12.71) and Cape Palmas (J & S., tetrasporangia

- 6961, 2.1.72). This unidentified species has irregularly divided, flexuous fila¬

ments, about 40 - 50 pm in diameter, arising from a creeping base whilst the

number of pericentral cells is just four.

Source :MNHN, Paris

MARINE ALGAE OF IVORY COAST

321

* Pterocladia capillacea (Gmelin) Bornet et Thuret

Growing as a loose mat on moderately wave-sheltered rocks in the upper part

of the lower eulittoral subzone.

Found at Cape Palmas (J & S., 6934, 2.1.72) and Fresco (A & C., tetrasporan-

gia - 19, - 682, 6556, 12.7.67) having been reported on the Guinea Coast from

Cameroun (as Pterocladia pinnata) and Ghana.

Taenioma perpusillum (J. Agardh) J. Agardh

Occuring as low ring-like patches on rocks, lithothamnia and occasionally

over Ralfsia, growing in moderately wave-sheltered situations and usually found

in the «algal turf» in more wave-sheltered places.

Collected at Cape Palmas (J & S., tetrasporangia - 6964, - 6968, 2.1.72),

Sassandra (J & S., 6972, 6873, tetrasporangia - 6923, - 6871, 30.12.72) and

Fresco (S., tetrasporangia - 496, 2-6.2.54) whilst having previously been reported

in the Gulf only from Ghana.

* Wrangelia argus (Montagne) Montagne

Growing as soft and plumose tufts on Laurencia tenera in moderately wave-

sheltered situations in the lower eulittoral subzone.

Found at Cape Palmas (J & S., carposporangia - 7006, 2.1.72) in Liberia and

known also from Cameroun (unpublished), Ghana and Togo.

CYANOPHYTA

Anacystis dimidiata (Kiitzing) Drouet et Daily

Growing together with filamentous blue-green algae as a scum floating on the

surface of pools in the littoral fringe which are influenced only by sea spray.

Found at Cape Palmas (J & S., 6959, 2.1.72) in Liberia and previously repor¬

ted from marine habitats in the Gulf of Guinea from Ghana and the offshore

island of Sao Tomé (as Chroococcus turgidus var. submarinus).

Microcoleus lyngbyaceus Gomont

Occuring mixed with larger algae or forming small dark greenish patches in

the upper eulittoral subzone, occasionally as a scum with other blue-green algae

on the surface of pools in the littoral fringe.

Collections from Cape Palmas (J & S., 6965, 6970, 6959, 2.1.72), Tabou

(J & S., 6918, 1.1.72) and Sassandra (J & S., 6977, 30.12.72) whilst also known

in the Gulf from Cameroun, Dahomey, Gabon, Ghana, Nigeria, Principe, Sao

Tomé and Togo.

Oscillatoria lutea Gomont

Forming a dirty yellowish-green slime on open rocks in the littoral fringe at

the entrance to the Tabou River (J & S., 6895, 1.1.72) in Ivory Coast having

previously been reported from Ghana.

322

D. M. JOHN

Schizothrix calcicola Gomont

Growing together with other blue-green algae as small slimy patches on mode-

rately wave-exposed rocks in the upper eulittoral subzone and also as a scum on

the surface of pools in the littoral fringe.

Found only at Cape Palmas (J & S., 6965, 6959, 2.1.72) and known previous-

ly from Dahomey, Ghana, Nigeria and Togo.

Schizothrix mexicana Gomont

Forming a lining over the floor of a shallow pool in the littoral fringe at the

entrance to the Tabou River (J & S., 6918, 1.1.72) in Ivory Coast and known

previously from Ghana and Nigeria in the Gulf of Guinea.

Fig. 1 — Map showing the localities along Ivory Coast and Cape Palmas in Liberia from

which collections were made.

AC KN OWLEDGEMENTS

I am most grateful to Pr. R. SOURIE, Laboratoire de Zoologie, Université de Poitiers,

for information regarding his collection of marine algae from Ivory Coast and to Pr. J.

FELDMANN, Laboratoire de Biologie Végétale Marine, Université de Paris, for loaning me

these plants. Thanks go to the Centre O.R.S.T.O.M. d’Adiopodoumé in Abidjan and the

Département de Biologie, Université d’Abidjan, for sending me what collections they held. I

am also grateful to Dr. F. DROUET, Academy of Natural Sciences, Philadelphia, U.S A., for

determining the Cyanophyta, to Dr. E. POST, Kiel, West Germany, for giving her opinion on

the brakish-water algae, and to Dr. E. WOLLASTON, Botany Department, University of

Adelaide, Australia, for identifying the Lasiothalia. Finally I wish to express my thanks to

Source : MNHN, Paris

MARINE ALGAE OF IVORY COAST

323

the Sous-Préfet at Tiassale and Tabou for their hospitality when in Ivory Coast and spécial

thanks go to Mr. F.O.K. SEKU for his most able assistance during ail phases of this study.

BIBLIOGRAPHY

AMOSSÉ, A., 1970 — Diatomées marines et saumâtres du Sénégal et de Côte d’ivoire. Bull.

I.F.AJ4. sér. A, 32 : 289-311.

ASKENASY, E., 1888 — Algen, mit Unterstützung der Herren E. BORNET, A. GRUNOW,

P. HARIOT, M. MOEBIUS, O. NORDSTEDT, 1-50, In ENGLER, A., Die Forschungs-

reise S Al.S. «Gazelle»... IV. Theil : Botanik (Algen), Berlin, 58 p.

BODARD, M., 1966a — Les Gracilaria et Gracilariopsis au Sénégal. Annls. Fac. Sci. Univ.

Dakar 19 :27-55.

BODARD, M., 1966b — Première liste des espèces d’algues présentes sur la Pointe de Sarène

(Sénégal). Notes afr. 3 : 81-89.

BCJRGESEN, F., 1934 — Some marine algae from the northern part of the Arabian Sea with

remarks on their geographical distribution. K. danske Vidensk. Selsk. Biol. Medd., 11 :

1-72.

BORGESEN, F., 1943 — Some marine algae from Mauritius. III. Rhodophyceae. Pt 2. Geli-

diales, Cryptonemiales, Gigartinales. Ibid., 19 : 1-85.

DANGEARD, P., 1951 — Sur les Gélidiacées de Dakar et de Port Etienne. Botaniste 35 :

21-24.

DIXON, P. S., 1958 — The structure and development of the thallus in the British species of

Gelidium and Pterocladia. Ann. Bot. 22 : 353-368.

DIXON, P. S., 1966 — On the form of the thallus in the Florideophyceae. 45-63. In CUT¬

TER, E. G. (ed.). Trends in plant morphogenesis, London and Colchester, 329 p.

DIXON, P. S., 1967 — The typification of Fucus cartilagineus L. and F. comeus Huds.

Blumea 15 : 55-62.

FOX, M., 1957 — A first list of marine algae from Nigeria. J. Linn. Soc. (Bot.), 55 : 615-

631.

JOHN, D. M., 1972 — The littoral ecology of rocky parts of the north-western shore of the

Guinea Coast. Botanica marina 15 :199-204.

KYLIN, H., 1938 — Verzeichnis einiger Rhodophyceen von Südafrika. Acta Univ. Lund 34 :

1-26.

LAWSON, G. W., 1956 — Rocky shore zonation on the Gold Coast./. Ecol. 44 : 153-170.

LAWSON, G. W., & PRICE, J. H., 1969 — Seaweeds of the western coast of tropical Africa

and adjacent islands : a critical assessment. I. Chlorophyta and Xantophyta. Bot. J. Linn.

Soc. 62 :279-346.

LEWIS, J. R., 1961 — The littoral zone on rocky shores - a biological or physical entity ?

Oikos 12 : 281-301.

POST, E., 1963 — Zur Verbreitung und Oekologie der Bostrychia-Caloglossa-Assozia.tion.

Int. Rev. ges. Hydrobiol. Hydrogr. 48 : 47-152.

POST, E., 1966a —Caloglossa ogasawaraensis in Westafrika. Hydrobiologia 27 : 317-322.

POST, E., 1966b — Neues zur Verbreitungsôkologie neuseelândischer und mittelamerika-

nischer Bostrychia-Caloglossa-Assoziation. Revue algol. 8 :127-150.

324

D. M. JOHN

SVEDELIUS, N. E., 1895 — Algen aus den Lândern der Magellanstrasse und Westpatogo-

nien. I. Chlorophyceae. 283-316. In Svenska Expeditionen Till Magellanslàndern. 3. Bo-

tany, Stockholm, 304 p.

325

SOME MARINE BENTHIC ALGAE FROM

PITCAIRN ISLAND

R. T. TSUDA *

SUMMARY. — The 21 species reported here include 4 Cyanophyta, 7 Chlorophyta, 5

Phaeophyta, and 5 Rhodophyta. The majority of the species are Malayan in origin, except

for the branching form of Lobophora variegata (Lamx.) Womersley ( Pocockiella nigrescens

(Sonder) Papenfuss sensu Papenfuss, 1943) which seems to be localized around Australian

or adjacent shores. Ail specimens are deposited in the author’s Herbarium at the University

of Guam.

RÉSUMÉ. — De cette île volcanique 21 espèces ont été identifiées. Elles sont d’origine ma¬

laise, à l’exception de la forme branchue de Lobophora variegata (Lamx.) Womersley qui

semble être localisée sur les rivages australiens adjacents.

I. INTRODUCTION

The marine benthic algae of those islands (Tuamotus, Marquesas and Pitcairn)

situated on the eastern fringe of Polynesia between 120 and 150 W longitude

are the least known in the tropical-subtropical Pacific Océan. The reason for our

limited knowledge of the algae in this area does not reflect the lack of interest

but the logistic difficultés in getting to these islands.

The only algal studies, thus far, reported from this area were carried out on

Raroia Atoll in the Tuamotus by DOTY (1954) and NEWHOUSE (1954). How-

ever, no systematic compilation of algae has been made for the Tuamotus,

except for the paper on the blue-green algae by NEWHOUSE (1954). There has

also been no published account on the marine algae of the Marquesas Islands. We

expect this situation to be changed by Dr. G. Valet of the University of Paris

who has informed me that he is presently studying the collections made from

this island group. The algae from the volcanic island of Pitcairn has never been

reported on nor has any listing of algae appeared for the three adjacent coral

islands (Henderson Island, Ducie Atoll, and Oeno Atoll).

When a proposed trip was being planned by the B. P. Bishop Muséum to this

area of the Pacific, I prevailed upon Dr John E. Randall to collect any algal spe-

* The Marine Laboratory, University of Guam, Agana Guam 96910 - Contribution n° 00.

Rev. Algol, N. S., 1976, XI, 3-4 : 325-331.

Source :MNHN, Paris

326

R.T. TSUDA

cimens he could fïnd from the area. The small collection reported here repre-

sents algal specimens collected by him from Pitcairn Island during december

1970 and january 1971. In addition, a collection of algae was also made from

the Marquesas which I forwarded to Dr Valet to be incorporated into his own

studies on the marine algae from this island group.

II. BRIEF DESCRIPTION OF ISLAND

Pitcairn Island (24 04’ S lat., 130° 06’ W long.) is a volcanic island about

4.5 km in circumference and 360 m high which lacks the typical cotai reef

formations found on most Pacific islands. The climate is subtropical with air-

temperature ranging from 20° C in august and september to 25° C in february

and march. The average annual rainfall.is about 175 cm (70 inches); the summer

months are slightly wetter than the winter months. The tidal range is about one

meter. For further information on the physical aspects of this island, I refer you

to CARTER (1967) from which most of the above information is taken.

III. STATION DESCRIPTIONS

The fïve stations where algal specimens were collected are described below.

The specimen numbers are those of the author.

Station 1 - Large tidepools and on rocks awash at shore, West Harbor, de¬

cember 29, 1970. (RT 4430 - 4445).

Station 2 - Large tidepool in surge zone, Christian’s Point, december 31,

1970. (RT 4446 -4451).

Station 3 - Off Gudgeon Harbor, 13 m deep, january 2, 1971. (RT 4452 -

4460).

Station 4 - Large pool, 5 m deep, St. John, january 7, 1971. (RT 4461 -

4463).

Station 5 - Boulder bottom with some sand and live corals, 21m deep, south

coast, january 20, 1971. (RT 4464).

IV. ANNOTED SPECIES LISTING

1. Division Cyanophy ta

Microcoleus lyngbyaceus (Kütz.) Crouan

DROUET, 1968 : 262.

Station 1 (RT 4433a) - The filaments are intermixed with Hormothamnion

enteromorpij.oides.

Hormothamnion enteromorphoides Bornet & Flahault

DAWSON, 1954 : 379, fîg. 3n.

Station X (RT 4433a) - The Blaments, 5 to 6 ftm in diameter, are beadlike in

appearance and possess conspicuous intercalary heterocysts.

BENTHIC ALGAE FROM PITCAIRN

327

Brachytrichia quoyi (Ag.) Bornet & Flahault

TILDEN, 1900 : 294, pl. 20 (Fig. 18).

Station 1 (RT 4445) - This alga appears a5 dark green hollow colonies about

5 mm in diameter. The beaded branched filaments, 2.5 to 4 pm diameter, taper

at one end and appear hair-like. Basal heterocystes are conspicuous and occasio-

nally intercalary heterocysts are présent.

Calothrix pilosa Harvey

FAN, 1956 : 130, fig. 2.

Station 1 (RT 4441b) - The few filaments présent are epiphytic on the green

alga Dictyosphaeria cavernosa.

2. Division Chlorophyta

Cladophora coelothrix Kütz.

VAN DEN HOEK, 1963 :40, fig. 55-78.

Station 1 (RT 4435b) - The alga appears in tufts, about 15 mn high, and

possesses sparingly branched filaments which arise in a dichotomous or trichoto-

mous manner. The cells are 350 to 600 pm long, and vary from 75 to 100 pm

in diameter at the base. However, the cells at the apex range from 25 to 30 pm

in diameter.

Bryopsis pennata Lamx.

EGEROD, 1952 : 370, fig. 7.

Station 3 (RT 4458) - This alga consists of pinnate siphons up to 25 mm high.

'Zaulerpa pickeringii Harvey & Bailey

VEBER VAN BOSSE, 1898:272, pl. 11, fig.7-8;TRONO, 1968 :167, pl. 15, fig. 5.

Station 3 (RT 4453) - This alga, up to 5 cm high, possesses whorls of bran-

:hing, ramuli which completely clothe the rizomes and assimilators (fig. 1). The

mly other Pacific islands on which this species has been reported are from Yap

TRONO 1968), Tahiti and the Tuamotus (WEBER VAN BOSSE 1898).

Mulerpa racemosa (Forsskal) J. Ag.

WEBER VAN BOSSE, 1898 : 357, pl. 31, fig. 5-8.

Station 1 (RT 4436, var. macrophysa), Station 2 (RT 4449, var. peltata).

‘ialimeda incrassata (Ellis) Lamx.

DAWSON, 1957 :109, fig. 13; HILLIS, 1959 : 365.

Station 1 (RT 4432), Station 4 (RT 4463) - The Pitcairn Island specimens do

not resemble the typical Halimeda incrassata specimens as found in the Micro-

nesian area, but strongly resemble DAWSON’s (1957) figure of H. tridens f. la-

mourouxii (J. Ag.) Weber van Bosse which HILLIS (1959) later places under H.

incrassata (fig. 2). My specimens are bushy with a small discoid holdfast. The

reniform segments are more or less similar in size and never exceed 3 mm in

length and 4 mm in width. Two tiers of utricles are présent. The secondary

utricles, 25/im long and 20 pm wide, give rise to 2 to 4 peripheral utricles which

are about 32 pm and 20 to 24 pm wide.

328

R. T. TSUDA

Cladophoropsis gracillima Dawson

DAWSON, 1950 :149, fïg. 12-13.

Station 1 (RT 4433b) - The filaments are sparingly branched and possess cells

which are up to 65 £tm in diameter and 1 mm long. Shorter basal cells, about

250 jUm long, are occasionally présent.

Dictyosphaeria cavernosa (Forsskal) Boerg.

EGEROD, 1952 : 350, fig. lb-f, 2f and 2g.

Station 1 (RT 4441) - A small specimen, 1.6 cm across, is ail that is présent in

the collection. However, the monostromatic thallus and the absence of trabecu-

lae seem to place the specimen in this species.

3. Division Phaeophyta

Ectocarpus breviarticulatus J. Ag.

DAWSON, 1954 : 398, fig. 14a-b.

Station 1 (RT 4437) - The specimen, intermixed with Sphacelaria tribuloides,

is stérile but possesses the characteristic hamate branches.

Sphacelaria tribuloides Meneghini

DAWSON, 1954 : 400, fig. 14i-j.

Station 1(RT 4444) - The propagulae of these specimens possess «horns»

which are not as protrusive as the Micronesian of Hawaiian specimens but still

fall within the circumscription for this species.

Dictyota acutiloba J. Ag.

SETCHELL, 1926 : 93.

Station 2 (RT 4450) - These specimens form loose clumps which are similar

in habit to growth-forms found in Hawaii. The branches are usually twisted

and possess acute apices. Reproductive bodies, which on these plants can be

either oogonia or potential tetraspores prior to cleavage, are scattered through-

out the médian surface of the thalli. This species has been reported from Tahiti

by SETCHELL (1926).

Lobophora variegata (Lamx.) Womersley

WOMERSLEY, 1967 : 221, PAPENFUSS, 1943 : 467, fig. 1-10; TAYLOR,

1971 :150, % 16-18.

Station 2 (RT 4447), Station 3 (RT 4452, RT 4454), Station 4 (RT 4461),

Station 5 (RT 4464) - The Pitcairn Island collection consists of one prostrate

specimen (RT 4454), (fig. 3). Ail of the other specimens are of the branching

form. It is with considérable hésitation that I place both forms under this one

species, since our prostrate Guamanian specimens never transform into the

branching form.

Sargassum coriifolium J. Ag.

WOMERSLEY and BAILEY, 1970 : 295, fig. 6, pl. 24, fig. 14.

Station 1 (RT 4430, RT 4442), Station 2 (RT 4446, RT 4448), Station 3

(RT 4455, RT 4456), Station 4 (RT 4462) - The majority of the specimens,

although showing a range in variation, seem to fit the description and figures

of the Solomon Island specimens (WOMERSLEY and BAILEY 1970). Ail of

BENTHIC ALGAE FROM PITCAIRN

329

the thalli possess terete branches (fîg. 4). The «leaves» vary considerably in

size and shape varying from entire, dentate, or duplicate. Ail specimens are

stérile except for one specimen (RT 4430) which possesses narrow straplike

«leaves» with elongate terete réceptacles unlike the réceptacles illustrated by

WOMERSLEY and BAILEY (1970). Further collections and observations are

needed of fruiting thalli before a defmite détermination can be made.

4. Division Rhodophyta

Gelidiopsis intricata (Ag.) Vickers

DAWSON, 1954 : 423, fig. 34.

Station 1 (RT 4438), Station 3 (RT 4457) - The specimens occur in tufts and

possess terete to compressed branches up to 500 jUm in diameter. One intercalary

stichidium is présent which has not been attributed to this species.

Corallina cuvieri Lamx.

Station 1 (RT 4434), Station 3 (RT 4460) - These fertile specimens were

identified by Dr. H. W. Johansen to whom I am most grateful.

Botryocladia skottsbergii (Boerg.) Levring

DAWSON, 1956 : 52, fig. 48.

Station 1 (RT 4443) - The collection consists of a single thallus which pos¬

sesses small subglobose vesicles about 3 mm in diameter on a 5 mm long bran-

ching stalk.

Centroceras clavulatum (C. Ag.) Montagne

DAWSON, 1954 : 446, fig. 54h.

Station 1 (RT 4435a) - The sparingly branched thalli are 100 to 150 pm in

diameter and possess the characteristic cellular spines at the nodes.

Chondria intricata Okamura

OKAMURA, 1912 :180, pl. 99.

Station 2 (RT 4451) - It is with hésitation that the Pitcairn Island specimen

is placed here.

ACKNOWLEDGEMENTS

I am grateful to Dr. John E. RANDALL of the B. P. Bishop Muséum for taking the time

from his busy fish collecting schedule to collect algal specimens for me. I also thank Dr. H.

William JOHANSEN of Clark University for his détermination of Corallina cuvieri Lamx.

Source :MNHN, Paris

330

R. T. TSUDA

Fig. 1. —Caulerpa pickeringii Harvey and Bailey, habit; Fig. 2 —Halimeda incrassata (Ellis)

Lamx., habit; Fig. 3 — Lobophora variegata (Lamx.) Womersley, habit of branching form;

Fig. 4. — Sargassum coriifolium J. Ag., habit.

BIBLIOGRAPHY

CARTER, R. M., 1967 — The geology of Pitcairn Island, South Pacific Océan. B. P. Bishop

Mus. Bull. 231 :1-38.

DAWSON, E. Y., 1950 — Notes on Pacific Coast marine algae IV. Amer. J. Bot. 37, 2 :

149-158.

DAWSON, E. Y., 1954 — Marine plants in the vicinity of the Institut Océanographique de

Nha Trang, Viet Nam.Pac. Sci. 8, 4 : 373-469.

DAWSON, E. Y., 1956 — Some marine algae of the Southern Marshall Islands. Pac. Sci.

10, 1 :25-66.

DAWSON, E. Y., 1957 — An annotated list of marine algae from Eniwetok Atoll, Marshall

Islands. Pac. Sci. 11, 1 : 92-132.

DOTY.M. S., 1954 —Floristic and ecological notes on Raroia .AtollRes. Bull. 33 : 1-41.

DROUET, F., 1968 — Révision of the classification of the Oscillatoriaceae. Monogr. Acad.

Nat. Sci. Philad. 15 :1-370.

EGEROD, L. E., 1952 —An analysis of the siphonous Chlorophycophyta. Univ. Calif.

PubL, Bot. 25, 5 :325-454.

FAN, K. C., 1956 — Révision of Calothrix Ag. Rev. Algol. 2, 3 :154-178.

HILLIS, L. W., 1959 — A révision of the genus Halimeda (Order Siphonales). Inst. Mar. Sci.

Texas 6 :321-407.

NEWHOUSE, J., 1954 - Ecological and floristic notes on the Myxophyta of Raroia. Atoll

Res. Bull. 33 :42-54.

OKAMURA, K., 1912 — Icônes of Japanese algae. Tokyo. 2 :1-191.

PAPENFUSS, G. F., 1943 —Notes on algal nomenclature. II. Gymnosorus J. Agardh.

Amer. J. Bot. 30 : 463-468.

SETCHELL, W. A., 1926 — Tahitian algae collected by W. A. Setchell, C. B. Setchell and

H. E. Parks. Univ. Calif. Publ., Bot. 12 : 61-142.

TAYLOR, W. R., 1971 — Notes on algae from the tropical Atlantic Océan. V. Br. PhycoL

7.6,2:145-156.

TILDEN, J. E., 1900 — The Myxophyceae of North America and adjacent régions, including

Central America, Greenland, Bermuda, the West Indies, and Hawaii. Minnesota Aloae 1 :

1-328.

TRONO, G. C. Jr., 1968 — The marine benthic algae of the Caroline Islands, I. Introduction,

Chlorophyta, and Cyanophyta. Micronesica 4, 2 :137-206.

VAN DEN HOEK, C., 1963 — Révision of the European species of Cladophora. Leiden.

WEBER VAN BOSSE, A., 1898 — Monographie des Caulerpes. Annls. lard. Bot. Buitenz.

15:243-401.

WOMERSLEY, H. B. S., 1967 - A critical survey of the marine algae of Southern Australia.

II. Phaeophyta. Aust. J. Bot. 15 :189-270.

WOMERSLEY, H. B. S., and BAILEY, A., 1970 — Marine algae of the Solomon Islands.

Phil. Trans. Roy. Soc. London. B.Biol Sci. 259, 830 : 257-352.

BENTHIC ALGAE FROM PITCAIRN

331

Source ; MNHN, Paris

Source : MNHN, Paris

333

ALGAL FLORA OF THE RICE-FIELDS AROUND

DEHRADUN, INDIA

M. KHAN & A. MATHUR *

SUMMARY. — 24 species of Cyanophyta and 24 species of Chlorophyta collected from the

rice-fields at the village Majra, situated near Clement Town, Dehradun hâve been recorded.

The successive occurence of various algal species through the months july-october are dis-

cussed in detail. The algal communities like tychophytes, benthophytes and epactiphytes

are prédominent while planktophytes and periphytes are found to be comparatively very

rare in the rice-fields. During présent survey 2 généra (Drapamaldiopsis and Zygogonium),

12 species of Cyanophyta and 17 species of Chlorophyta hâve been recorded for the first

time from Dehradun.

RÉSUMÉ. — 24 espèces de Cyanophycées et 24 espèces de Chlorophycées ont été récoltées

dans les rizières du village de Majra, situé près de Clement Town (Dehradun). La succession

des diverses espèces d’algues de juillet à octobre est analysée : les communautés tychophy¬

tes, bentophytes et epactiphytes sont prédominantes alors que les planctophytes et les péri-

phytes sont rares. Au cours de cette étude 2 genres (Drapamaldiopsis et Zygogonium) et 12

espèces de Cyanophycées ainsi que 17 espèces de Chlorophycées ont été récoltées pour la

première fois à Dehradun.

I. INTRODUCTION

Algal survey reported so far (GONZALVES et GANGLA 1949; GUPTA

1966; SHUKLA 1971; SINGH 1939, 1961; SUBRAHMANYAN et al. 1965;

VENKATARAMAN 1971) from different parts of India can not be deemed as

adéquate and commensurative with the needs of the wast rice-growing areas

spread out in many parts of the country. Also, there exist no previous compré¬

hensive records on the algal flora of rice fields of Doon Valley, Western Uttar

Pradesh (cf. KHAN 1970 a, b et c; KHAN & USHA 1971; KHAN & KUMARI

1972; KHAN & BARTHWAL in press).

a. LOCATION AND PERIOD OF STUDY

The area under study is Clement Town which is situated on both sides of Sa-

haranpur road near village Majra at the altitude of 548 meters. Observations hâve

been made on the algal flora of the rice-fields from the month of july till the end

of october during the years 1971 and 1972, which coincide with the sowing har-

* Department of Botany, D. A. V. post-graduate College, Dehradun, U. P., India.

Rev. Algol., N. S., 1976, XI, 3-4 : 333-337.

Source : MNHN. Paris

334

M. KHAN & A. MATHUR

vesting months of rice crop in the area.

b. CLIMATE AND SOIL CONDITIONS

The climate of the valley is best suited for the cultivation of the rice. The

mean température in the last week of june is 26 C and in october 21 C, which

is idéal for sowing and maturity of the crop respectively. During the month of

july climate is very humid (84 - 94%) due to heavy rain fall (472 - 599 mm). The

water table is 12 meters below the surface and irrigation facilities are adéquate.

The soil is rich loamy and one of the best in the whole of Dehradun valley.

II. SUCCESSION OF ALGAE IN NATURE

The mansoon usually sets in, in this région in the third or fourth week of june

and the fields are ploughed after one or two rain falls. The early variety of paddy

is sown in the upland fields in the first week of july. As the fields are in a conti-

nuously disturbed State, there is apparently no growth of algae. The extra water

is drained into low lying areas and the low land fields are there fore floodcd. The

common algae (Table I) in the upland fields were Cylindrospermum majus, C.

stagnale, Anabaena torulosa, Aulosira aenigmatica and Oedogonium vanoyea-

num. Species of Spirogyra and Zygnema were in a végétative State. Anabaena

torulosa, Cylindrospermum majus and C. stagnale were found as elongated

colonies on moist soil immersed in three to five centimeters deep in water. Spi¬

rogyra grew in drains, along the sides or where water had accumulated in the

fields. In addition Microcoleus vaginatus and Aulosira aenigmatica formed a

green or bluish green stratum on moist soil in some fields. The low land fields are

usually in knee deep water and as the water was muddy no growth of algae was

therefore visible during this month.

There was heavy rain fall during the first fortnight of August, and the maxi¬

mum and minimum température varied from 22 to 26 C and 26 -30 C respec¬

tively. The high température and humidity (49 - 97%) provided very suitable

conditions for the growth of algae and these were on the whole found to be very

abundant. The most common algae found during this period were the species of

Cylindrospermum and Microcoleus, which covered the entire surface of the soil

in some of the upland fields. The well developed colonies assumed a palmate

form with long finger like processes.

In a few fields a very prominent associations of Nostoc, Cylindrospermum

and Microcoleus were found to cover the surface of water as leathery dirty-

bluish stratum. As the water receded in these fields the algal stratum remained

sticking to the stalks of paddy plants. Among the other forms Mougeotia, Chae-

tophora and Nitella were conspicuous. During the later half of the month of

august a number of other forms like Nostoc punctiformae, Oscillatoria annae, O.

sancta, Anabaena sphaerica, A. iyengarii and Scytonema hofmanni were pré¬

sent, the latter which was présent from the beginning of the month spread consi-

derably on moist soil in the fields.

ALGAL FLORA OF THE RICE-FIELDS

335

The low land water logged fields flooded due to heavy and continuous rains

were fïlled with disturbed and muddy water, due to which no algal forms were

apparently growing during the second fortnight. Only a few free floating masses

of Anabaena, Sirogonium inflatum and Lyngbya martensiana hâve been collec-

ted.

There were light rains during the earlier part of september and the maximum

and minimum température varied from 17-21 C to 26-30 C respectively. Du¬

ring the later half of the month there is a dry spell and température showed a

iittle variation. Many of the upland fields dry up and are harvested. Species of

Cylindrospermum was still conspicuous during this month. At the end of the

month it desappeared almost completely. The abundant algal species during this

period were Scytonema hofmanni, Nitella dictyosperma, N. translucens. Chara

appeared later in abundance along with Iittle amount of Draparnaldiopsis indica.

In a few fields Chaetophora elegans, Scytonema hofmanni and Nostoc continued

to be prominent component of the algal végétation till the fields dried up.

In the low land fields number of algae increased considerably. Scytonema

coactile which occurs in free floating masses formed bright bluish green cushion

of erect filaments on moist soil along the sides of the fields. Microcoleus vagina-

tus appeared to be very common on moist soil in and around these fields. Gra-

dually a very profuse growth of Chara and Nitella took place in most of the

fields which were in végétative condition. Aulosira fertilissima was common in

most of the fields. A number of chlorophycean members like Zygnema collinsia-

num, Zygogonium indicum and species of Spirogyra were also found.

In october the upland fields were completely dry and rice crop had already

been harvested by now. No growth of the algae was apparent. At this time the

low land fields were rich in algal growth. The water level fell considerably and

there was an abundant growth of Mougeotia and Aulosira fertilissima. Species

of Spirogyra and Zygnema were the other prominent constituents of the algal

végétation. In the middle of the october species of Chara, Nitella, Aulosira and

Oedogonium were abundant in low land fields.

III. DISCUSSION

It is apparent from the table-I and also from the foregoing succession ac-

counts that the species of Cylindrospermum are common during the beginning

and Scytonema and Oedogonium are at the end of the season.

Though the percentage of blue-green and green algae are equal but so far the

frequency and dominance are concerned, the blue-green algae are very prédomi¬

nent. Generally, the blue-green algae show a overwhelming prépondérance over

the other classes of algae particuiarly Chlorophyceae in India (GONZALVES &

GANGLA 1949; GUPTA 1966; SUBRAHMANYAN et al. 1965; VENKATA-

RAMAN 1971) as against the temperate soil where reverse is the case. However,

in the fields under discussion green algae are equally dominant as it was shown

earlier by SINGH (1939) and SHUKLA (1971).

336

M. KHAN & A. MATHUR

The members of Cyanophyta are abundant in early months of july and

august while during september and october, the members of Chlorophyta are

prédominent. The présent investigation shows that the growth of the algae in

nature is controlled to a great extent by the seasonal variations as well as by

ecological conditions to some extent as it was earlier shown by GUPTA (1966).

In the rice-fields of U. P. and Bihar occur a dominant and widespread nitro-

gen-fïxing algal community of blue-green algae constituted mainly by Aulosira

fertilissima (SINGH 1936, 1961; SHUKLA 1971). VENKATARAMAN (1971)

and SUBRAHMANYAN et al. (1965) also hâve recorded ubiquitous occurence

of Aulosira fertilissima in the States of Madras and Kérala and Orissa respective-

ly. However, in Maharashtra this genus has not been recorded from the rice fields

(GONZALVES and GAN GLA 1949).

The distribution of Charophyta is very interesting. Species of Chara are

confined to central régions of the fîelds whereas the species of Nitella are found

only on the margins.

The algal species which were growing in the rice-fields, on the basis of their

habitat may be categorised into fïve algal communities as tychophytes, bento-

phytes, epactiphytes, periphytes and planktophytes. Planktophytes and periphy-

tes are comparatively rare.

It is also interesting to note that in the rice-fields of Doon valley members of

Volvocales, Chlorococcales, Ulotrichales and Cladophorales are endrely absent in

contrast to the observations of SHUKLA (1971) and GONZALVES and GAN-

GLA (1959).

ACKNOWLEDGEMENT

The authors are grateful to Dr. Y. S. R. K. SARMA, Professor of Botany, Benaras Hindu

University, Varanasi-5, for his valuable ad vice.

ALGAL FLORA OF THE RICE-FIELDS

337

TABLE I. Algal species showing their frequency in rice-fields

* Recorded for the First time from Dchradun, a - abundance, c - common, r - rare,

B - Benthophytes, E - Epactiphytcs, P - Periphytes, PI - Planktophytes, T - Tychophytes.

TAXA ^TypT 1 ^ July Aug ' Sept ' ° ct-

1. Oscillatoria annae Van Goor B

2. *0. sancta (Kutz.) Gomont B

3. O. obscura Brühl et Biswas B

4. O. subbrevis Schmidle. B

5. Lyngbya martensiana Menegh. B

6. Microcoleus vaginatus (Vaucher) Gomont. B

7. Cylindrospermum majus Kutz. P

8. *C. stagnale (Kutz.) Born.et Flah. P

9. C. doryphorum Brühl et Biswas P

10. Nostocpunctiforma (Kutz.) Hariot. T

11. N. muscorum Ag. B

12. *N. pruniforme { L.) Ag. T

13. *AnabaenasphaericavaT.attenuataBh!ü:!Ld. T

14. *A. oryzae Fritsch. T

15. *A. iyengarii var. tenuis Rao T

16. *A. torulosa (Carm.) Lagerh. B

17. *Aulosira fertilissima var. tenuis Rao PI

18. *A. aenigmatica Fremy B

19. A. prolifica Bharadwaja PI

20. Scytonema coactile Mont, ex Born.et Flah. T

21. *S. bohneri Schmidle T

22. *S. hofmanni Ag. P

23. *S. bewsii Fritsch et Rich T

24. S. miràbile (Dillw.) Born. T

25. *Mougeotia drouetii Transeau T

26. *M. laetivirens (Braun) T

27. Zygnema collinsianum Transeau T

28. *Zygogonium indicum Randhawa T

29 *Spirogyra parvula (Trans.) Czurda E

30. *S. submaxima Transeau E

31. *S. rectangularis Transeau E

32. *Sirogonium inflatum Dixit T

33. *Oedogonium hindustanense Kamat E

34. *0. crassum (Hassal) Wittrock E

35. O. fragile vclt. Abyssinicum Hirn. E

36. *0. himii Gutwinskii P

37. *0. vanoyeanum Gauth-Liev. E

38. *Drapamaldiopsis itidica Bharadwaja E

39. Chaetophora elegans (Roth.) Agardh P

40. Nitella acuminata Braun E

41. *N. translucens Agardh E

r r

c a

a a

338

M. KHAN & A. MATHUR

42. *N. flagellifera Groves et Allen E

43. *N. dictyosperma Groves E

44. *N. pseudotenuissima Kundu E

45. Chara burmanica Pal B

46. C. vulgaris Linn. B

47. C. contraria Kutz. B

48. *C. bharadwajae Sarma et Khan B

BIBLIOGRAPHY

GONZALVES, E. A., and GANGLA, K. S.,1949 — Observations on the algae of Paddy field

soils. Jour. Uni. Bombay 18 : 51-59.

GUPTA, A. B., 1966 — Algal flora and its importance in the economy of rice-fields. Hydro-

biologia 28 :213-222.

KHAN, M., 1970 a — Fundamentals of Phycology. Pub. Bishen Singh Mahendra Pal Singh,

Dehradun, India : 21-22.

KHAN, M., 1970 b — Algal flora of Dehradun. I. Myxophyceae. P/iyfeos 9 : 126-131.

KHAN, M., 1970 c — Algal flora of Dehradun. II. Chlorophyceae. G. K. V. J. Sc. R. 2 :

87-92.

KHAN, M., and BARTHWAL, S. D., in press — Algal flora of Dehradun. V. Ulotrichales,

Siphonales and Charales. G. K. V. J. Sc. R.

KHAN, M., and KUMARI, S., 1972 — Some additions to the algal flora of Dehradun. III.

Cyanophyta. Jour. Ranchi Uni. 8 : 298-300.

KHAN, M., and USHA, Y., 1971 — Algal flora of Dehradun. IV. Zygnemaceae. G. K. V. J.

Sc. R. 3 : 26-28.

SHUKLA, A. C., 1971 — Systematic description of algae from Panki rice-fields, India. Rev.

Algol. 3 :257-270.

SINGH, R. N., 1939 — An investigation into the algal flora of Paddy field soils of the

United Provinces. l.Indian Jour. Agri. Sci. 9 : 55-77.

SINGH, R. N., 1961 — Rôle of blue-green algae in nitrogen economy of Indian Agriculture.

Pub. I. C. A. R., New Dehli, India.

SUBRAHMANYAN, R., RELWANI, L. L., and MANNA, G. B., 1965 — Fertility build up of

rice-field soils by blue-green algae.Proc. Indian Acad. Sci. 62 : 252-272.

VENKATARAMAN, G. S., 1971 — Handbook of Manures and Fertilizers. Pub. I. C. A. R.,

New-Dehli, India : 240-252.

339

BOURRELLYODESMUS

NOUVEAU GENRE DE DESMIDIACEES

Pierre COMPERE *

Depuis que TEILING (1948, 1967) a reclassé dans le genre Staurodesmus les

Desmidiacées à membrane lisse pourvues d’une seule épine à chaque angle de la

cellule, le genre Arthrodesmus, tel qu’il est compris par BOURRELLY (1966,

p. 432) ou par COÛTÉ et ROUSSELIN (1975, p. 115) est devenu extrêmement

hétérogène, groupant, d’une part des espèces à membrane lisse pourvues de plu¬

sieurs épines à chaque angle et d’autre part des espèces à membrane ornementée

pourvues d’une seule épine à chaque angle. En bonne logique, on ne peut laisser

dans le même genre les sections Polyancanthium et Ornatae, qui ne diffèrent de

Staurodesmus que par un seul caractère (nombre d’épines par angle ou ornemen¬

tation de la membrane) mais qui diffèrent l’une de l’autre par ces deux caractères

réunis.

Nous avons montré par ailleurs (COMPERE 1976a) que le nom de genre Ar¬

throdesmus Ralfs 1848 (Desmidiacées), homonyme postérieur de Arthrodesmus

Ehr. 1838 (Scénédesmacées) est un nom illégitime et qu’il ne paraît pas très

opportun de le conserver en raison des vues divergentes exprimées récemment

par divers auteurs (BOURRELLY, loc. cit.; B1CUDO 1975a) sur ses limites et sur

sa typification.

La plus grande partie des espèces groupées jusqu’ici dans le genre Arthrodes¬

mus (section Tetracanthium, à membrane lisse et angles de l’hémisomate portant

une seule épine) ont déjà été reclassées par TEILING au sein de son nouveau genre

Staurodesmus; on pourrait y joindre certaines espèces de la section Octacan-

thium comme A. mucronulatus : la belle étude que B1CUDO (1975b) vient de

consacrer à la variabilité de cette espèce, notamment en ce qui concerne le nom¬

bre et la disposition des épines, montre bien qu’il est impossible de la séparer, au

niveau générique, des espèces du genre Staurodesmus (voir notamment ses figu¬

res 3, 4, 5, 6 et 7, montrant des spécimens à une épine par angle et des spéci¬

mens dichotypiques, où un des hémisomates montre deux épines par angle et

l’autre une seule épine par angle).

D’autres espèces des sections Octacanthium et Polyacanthium, portant qua¬

tre, six ou un plus grand nombre d’épines par hémisomate, trouveraient proba-

* Jardin Botanique National de Belgique, Domaine de Bouchout, B 1860 Meise, Belgique.

Rev. Algol., N. S., 1976, XI, 3-4 : 339-342.

Source : MNHN, Paris

340

P. COMPERE

blement mieux leur place dans le genre Xanthidium ; cela a déjà été proposé par

RALFS (1848) pour Xanthidium octocorne Ralfs et par DEFLANDRE (1929)

pour Xanthidium impar (Jacobs.) Défi. Une révision du genre Xanthidium et

de ces deux sections d’Arthrodesmus serait certainement des plus utiles pour

nous fixer sur ce point.

Reste alors le cas des espèces à membrane ornementée, pourvues d’une seule

épine de chaque côté de l’hémisomate, comme par exemple Arthrodesmus heimii

Bourr., connu de diverses parties de l’Afrique et que nous retrouvons dans quel¬

ques récoltes de la région du lac Tchad (COMPERE 1976b). Il n’est pas possible

d’en faire un Staurodesmus, à cause de l’ornementation de sa membrane; on ne

peut non plus le rapporter au genre Xanthidium, puisqu’il ne présente qu’une

seule épine de chaque côté de l’hémisomate. On a bien proposé d’en faire un

Cosmarium (LIND 1971, p. 548) mais nous pensons, avec COÛTÉ et ROUSSE-

LIN (1975, p. 115), qu’il n’est pas opportun de réintroduire dans le genre

Cosmarium une forme possédant de telles épines latérales, et d’ajouter ainsi à

l’hétérogénéité de ce genre énorme, déjà beaucoup trop hétérogène. Finalement,

la seule solution respectant une certaine homogénéité des différents genres im¬

pliqués paraît bien être la création d’un nouveau genre pour ce dernier groupe

d’anciens Arthrodesmus. Cette conclusion resterait d’ailleurs valable si le nom

Arthrodesmus devait être conservé, soit dans le sens de BICUDO (1975a) pour ce

qui est actuellement appelé Staurodesmus, avec A. convergens comme type, soit

dans le sens de BOURRELLY (1966), avec A. octocornis comme type, pour les

espèces à membrane lisse possédant deux ou plusieurs épines de chaque côté de

l’hémisomate. Nous sommes heureux de pouvoir dédier ce nouveau genre de

Desmidiacées au Professeur P. BOURRELLY, du Muséum National d’Histoire

Naturelle de Paris, qui a été le premier à découvrir son espèce la plus caracté¬

ristique.

BOURRELLYODESMUS COMPERE, GEN. NOV.

a Staurodesmo membrana in media parte incrassata, verrucis vel scrobicula-

tionibus omata differt; a Xanthidio angulis unispinosis differt.

Semi-cellulae ellipsoidales vel reniformes, ab apice visae ellipticae, spina

unica utroque munitae, in media parte incrassatae, verrucosae vel scrobicula-

tae.

Species typica : BOURRELLYODESMUS HEIMII (Bourrelly) Compère,

comb. nov., fig. 1.

Basionyme -.Arthrodesmus heimii Bourr., Bull. I.F.A.N. 19 : 1079, fig. 105,

106 (1957).

Synonymes : Arthrodesmus stellifer Grônblad & Scott, Acta Bot. Eenn. 58 :

38, fig. 265-267 (1958).

Cosmarium tagmasterion Sc. & Presc. var. africanum Lind, Nova

Hedwigia 22 : 548, pl. 4 fig. 5, pl. 10, fig. 18 (1971).

BOURRELLYODESMUS

341

ig. 1 : Iconotype de Bourrellyodesmus heimii; reproduction des figures originales de Ar-

throdesmus heimii (BOURRELLY 1957 : pl. 12, fig. 105 et 106). Le petit trait au voi¬

sinage de chaque figure indique l’échelle de lOpm.

Il est très probable que d’autres espèces de l’ancien genre Arthrodesmus,

:lles que A. incrassatus Lagerh., A. notochondrus Lagerh., A. spechtii Scott et

resc., possédant à la fois une inflation médiane ornementée et une seule épine

e chaque côté de l’hémisomate, doivent rentrer dans le genre Bourrellyodesmus;

imme nous n’avons pas vu de matériel de ces espèces, nous nous abstiendrons

e proposer ici d’autres nouvelles combinaisons.

BIBLIOGRAPHIE

ICUDO, C. E. M., 1975a — Typification of the generic Desmid name Arthrodesmus (Des-

midiaceae). Beih. Nova Hedwigia 42 : 33-38.

1DUDO, C. E. M., 1975b — Polymorphism in the desmid Arthrodesmus mucronulatus and

its taxonomie implications. Phycologia 14 : 145-148, 9 fig.

OURRELLY, P., 1966 — Les algues d’eau douce. I : Les algues vertes, Paris, N. Boubée &

Cie, 511p., 117 pl.

OMPERE, P., 1976a — The typification of the genus Arthrodesmus (Algae-Chlorophyta).

Taxon 25 (sous presse).

342

P. COMPERE

COMPERE, P., 1976b — Algues de la région du lac Tchad. VI. Desmidiées. Cah. O.R.S.T.

OJM., sér. Hydrobiol. 10 (en préparation).

COÛTÉ, A. et ROUSSELIN, G., 1975 — Contribution à l’étude des algues d’eau douce du

Moyen-Niger (Mali). Bull. Mus. Nat. Hist. Nat., sér. 3, 277 : 73-175, 19 pl.

DEFLANDRE, G., 1929 — Notes sur 1 ’Arthrodesmus impar (Jacobs.) Groenbl. et ses varia

rions, suivies de remarques sur la délimitation des genres Arthrodesmus et Xanthidium.

Bull. Soc. Bot. France 76 :130-139.

LIND, E. M., 1972 — Some Desmids from Uganda. Nova Hedwigia 22 : 535-585, 13 pl.

RALFS,J., 1848 — TheBritish Desmidieae, XXII, 226 p. 35 pl.

TEILING, E., 1948 — Staurodesmus genus novum containing monospinous Desmids. Bot.

Not. 49-83, 72 fig.

TEILING, E., 1967 — The desmid genus Staurodesmus, a taxonomie study. Ark. Bot. 6

468-629,31 pl.

Source : MNHN, Paris

343

PREMIER INVENTAIRE DES DIATOMEES MARINES

DU LAGON DE TIAHURA

(ILE DE MOOREA - POLYNESIE FRANÇAISE).

M. RICARD *

ÉSUMÉ. — Au cours de deux missions en Polynésie Française, en juillet 1974 et août 1975,

•es récoltes de phytoplancton ont été effectuées à la surface du lagon de Tiahura (île de

loorea) au moyen d’un filet à phytoplancton. L’inventaire préliminaire des diatomées de ce

igon et de l’océan environnant est accompagné de mesures quantitatives et de données

hysico-chimiques. Chaque taxon est assorti de commentaires sur sa fréquence et sa répar¬

don géographique. Les résultats sont comparés avec ceux obtenus dans les lagons de Tahiti.

JMMARY. — A preliminary list of diatoms collected in two stations at Moorea island

rench Polynesia) is given here and its biogeographic composition is discussed. 235 taxa of

atoms hâve been identified from net samples and some quantitative data are presented :

•Ils counts after sédimentation of water samples, physical and chemical values. Phyto-

ankton populations in Tahiti and Moorea are compared.

INTRODUCTION

Nous avons effectué, en juillet 1974 et août 1975, deux séjours à l’Antenne

i Muséum et de l’Ecole Pratique des Hautes Etudes de Moorea (Polynésie

rançaise) afin d’étudier la concentration en pigments chlorophylliens et la pro-

ictivité primaire des eaux du lagon de Tiahura. A cette occasion nous avons ré-

ilté, au filet, le phytoplancton de surface du lagon et de l’océan; ces récoltes

nt permis de dresser un premier inventaire taxinomique des diatomées et d’en

ire un bilan quantitatif grâce à des prélèvements d’eau. La liste taxinomique

t accompagnée de remarques sur la fréquence et la répartition biogéographique

; chaque taxon. Les résultats obtenus à Moorea sont comparés à ceux de Tahi-

. MATERIELS ET METHODES

RECOLTES

Les récoltes ont été réalisées, en surface, au moyen de bouteilles à hydrologie

Laboratoire de Cryptogamie, Muséum National d’Histoire Naturelle, 12 rue de Buffon,

5005 Paris — L. A. n° 257 (C.N.R.S.) et Antenne du Muséum et de l’E. P. H. E., B.P. 562,

apeete, Tahiti, Polynésie Française.

ev. Algol., N. S., 1976, XI, 3-4 : 343-355.

Source : MNHN , Paris

344

M. RICARD

de type Van Dorn et de filets à microplancton de vide de maille de 42jUm, traî¬

nés à faible vitesse durant 10 minutes à l’arrière d’une embarcation à moteur.

Les prélèvements ont été faits dans le lagon puis dans l’océan à 500 mètres

environ de la barrière récifale. Les échantillons ont tous été fixés au formol

neutre à 4% et conservés 3 à 6 mois avant l’observation. Les échantillons des¬

tinés à l’étude qualitative ont été examinés au microscope ordinaire à fond clair

après avoir subi un traitement destiné à les nettoyer et à les inclure dans une ré¬

sine réfringente (RICARD 1975 b). Les comptages quantitatifs ont été réalisés

sous un microscope inversé Wild M40 selon la technique décrite par UTER-

MOEHL (1958).

b. AIRES DE REPARTITION BIOGEOGRAPHIQUES

Les aires de répartition des diatomées et des dinoflagellés sont assez mal défi

nies et chaque auteur donne une signification différente aux termes antérieure

ment définis ou bien en introduit de nouveaux. DEACON (1933) et HENDEY

(1937) parlent de formes antarctiques, subantarctiques et subtropicales, alors que

KARSTEN (1907) préfère parler d’espèces ubiquistes, tempérées, tempérées tropi

cales et tropicales, et STEEMAN-NIELSEN (1939) de formes tropicales et subtro

picales. ANGOT (1961) définit les mers tropicales comme celles dont la tempéra

ture ne descend jamais au-dessous de 22 C tout au long de l’année, etSOURNIA

(1969) reprend ces définitions ainsi que certains termes utilisés par les auteurs pré

cités dans sa liste taxinomique du phytoplancton du canal du Mozambique (1970)

La nomenclature la plus complète concernant les aires de répartition a éti

introduite par CUPP (1943) : elle considère des espèces arctiques, boréales

tempérées nord, tempérées sud, subtropicales, tropicales et ubiquistes.

Tous les auteurs emploient ces différents termes mais rares sont ceux qu

donnent, à l’exemple de DEACON, une définition précise de chaque aire. Le:

aires de répartition que nous proposons sont au nombre de quatre : arctique

antarctique, tempérée, intertropicale; l’aire tempérée est divisée en deux sous

aires, tempérée chaude et tempérée froide.

aire arctique et antarctique :

Elles s’étendent d’une part du pôle nord jusqu’à la latitude de 60° N, et d’autr-

part du pôle sud jusqu’à la latitude de 60° S. Ces deux aires correspondent res

pectivement aux anciennes aires arctiques et subarctiques, ou antarctiques e

sub an tare tiques.

aire tempérée :

L’aire tempérée froide va des latitudes 60° N ou S aux latitudes 48° N ou S

elle correspond, pro parte, aux zones boréales et aux zones tempérées Nord oi

Sud. L’aire tempérée chaude va des latitudes 48° N ou S aux latitudes 25° N ot

S; elle correspond, pro parte, aux zones tempérées Nord ou Sud ainsi qu’au.'

zones tempérées tropicales. Cette subdivision en 2 zones tempérées froide ei

DIATOMÉES MARINES DE TIAHURA

345

chaude est plus particulièrement applicable aux mers européennes,

aire intertropicale :

L’aire intertropicale englobe les tropiques du Cancer et du Capricorne et s’étend

de la latitude 25 N à la latitude 25 S; cette aire recouvre les anciennes zones

équatoriales, tropicales équatoriales, tropicales, ainsi qu’une partie des zones

tempérées tropicales.

Cette division en quatre zones est arbitraire dans la mesure où elle ne tient pas

compte des courants marins et des convergences océaniques pas plus que des

formes de transition entre ces différentes aires, mais permet la distinction entre

les taxons endémiques et les taxons cosmopolites. Cette distinction n’est pas

réalisée pour les répartitions qui font intervenir les formes de transition, qu’elles

soient subtropicales, subantarctiques ou subtempérées. Sans nier l’existence des

formes de transition entre les différentes aires de répartition, nous considérons

qu’une espèce de transition peut être classée comme appartenant en propre aux

deux aires.

Pour chaque taxon nous avons fait une compilation des différents lieux de

récolte en nous attachant plus particulièrement aux auteurs ayant travaillé dans

les eaux intertropicales des trois océans. Citons plus particulièrement SUBRAH-

vlANYAN (1946, 1958 a et b), SUBRAHMANYAN et SARMA (1960), WOOD

1961 a et b, 1963 a et b) pour l’océan Indien, SILVA (1956, 1960), SOURNIA

1966, 1968 a et b), TRAVERS et TRAVERS (1965), ANGOT (1966) pour

Madagascar et le canal de Mozambique, REYSSAC (1966 a et b) pour la Côte

i’Ivoire, ALLEN (1937), ALLEN et CUPP (1938), CUPP (1943) pour la côte

:st des Etats-Unis, GILMARTIN et REVELANTE (1974) pour les Iles Hawaii,

l)ESROZIERES (1969) et HASLE (1959, 1960) pour le Pacifique équatorial.

. CALCUL DES FREQUENCES DES ESPECES

Sur la liste taxinomique sont indiquées les fréquences respectives de chaque

axon pour les récoltes réalisées dans les lagons, en haute mer et en eau douce,

^a fréquence s’exprime en pourcentage et correspond au rapport entre le nombre

les individus d’un même taxon et le nombre total des individus observés dans

a récolte (REYNAUD-BEAUVERIE 1936). La fréquence s’oppose à l’abon-

lance qui est une notion d’appréciation quantitative qui s’exprime en degrés

d’abondance allant de 1 à 5.

La fréquence de chaque taxon a été calculée après un comptage effectué sur

1000 individus dénombrés sur 4 lames différentes pour remédier le plus possible

à une répartition non homogène des diatomées sur la préparation. Il apparaît

expérimentalement qu’il est nécessaire de compter un certain nombre d’indi¬

vidus pour obtenir des fréquences stables : au-delà de 500 individus dénombrés,

les fréquences se stabilisent et se répètent si plusieurs comptages sont effectués

sur une même récolte, alors que pour des valeurs inférieures ces fréquences

oscillent largement. Pour des facilités de calcul et d’écriture nous avons compté

Source : MNHN. Paris

346

M. RICARD

1000 individus par récolte.

Les fréquences indiquées correspondent aux fréquences cumulées des taxons

inventoriés dans tous les lagons de Tahiti et de Moorea, soit 115 récoltes. Nous

n’avons pas pris en considération les populations des lagons des îles sous le vent

en raison du faible nombre de récoltes.

Nous avons choisi 3 écarts de pourcentage pour définir les fréquences suivan¬

tes :

Très fréquent

Fréquent

Rare

Absent

50 à 100 % TF

10 à 50% F

Oà 10% R

0% (-)

III. RESULTATS

a. COMPOSITION TAXINOMIQUE

L’inventaire qualitatif compte 235 taxons dont 67 diatomées centriques et

168 diatomées pennées qui se répartissent ainsi (cf. Annexe) :

- 69 taxons cosmopolites

- 88 taxons tempérés tropicaux

- 33 taxons tropicaux

- 34 taxons tempérés signalés pour la première fois en milieu tropical

- 2 taxons arctiques et/ou antarctiques

Les diatomées tropicales endémiques représentent 14% de la population glo¬

bale, les diatomées cosmopolites 30% et les diatomées tempérées tropicales 36%.

Ces valeurs correspondent à celles trouvées par SOURNIA à Tuléar (1968) : 11%

de diatomées tropicales endémiques, 33% cosmopolites et 35% tempérées tropi¬

cales.

La répartition des taxons dans le lagon et l’océan est la suivante :

- 111 taxons (52 centriques et 59 pennées) peuplent à la fois le lagon et

l’océan, soit 48% du total.

- 109 taxons (7 centriques et 102 pennées) sont récoltés uniquement dans le

lagon, soit 47% du total.

- 14 taxons (12 centriques et 2 pennées) se trouvent seulement dans l’océan,

soit 5% du total.

Cette répartition met en évidence la prépondérance des diatomées benthiques

dans les eaux du lagon, mais également la forte influence des eaux océaniques

qui se traduit par la présence, dans le lagon, de diatomées planctoniques et plus

particulièrement de diatomées centriques.

La comparaison entre les populations de Moorea et de Tahiti (RICARD 1970

a et b, 1974, 1975 a et b) accuse la différence de composition qualitative des

deux populations : à Tahiti, la part des diatomées pennées représente 84% de la

DIATOMÉES MARINES DE TIAHURA

347

population globale du lagon alors qu’à Moorea elle n’atteint que 73%; inverse¬

ment, la composition du plancton océanique est la même pour les deux îles à

proximité de la barrière récifale : 50% de diatomées centriques et 50% de diato¬

mées pennées. D’autre part la diversité spécifique est plus grande dans les lagons,

227 taxons ont été dénombrés à Moorea et 491 à Tahiti, que dans les prélève¬

ments réalisés à l’extérieur de la barrière, 125 taxons seulement ont été dénom¬

brés à Moorea et 144 à Tahiti où les récoltes ont été pourtant dix fois plus nom¬

breuses.

b. COMPOSITION QUALITATIVE

Les comptages cellulaires au microscope inversé font apparaître une extrême

pauvreté numérique du phytoplancton : 1500 à 5600 cellules par litre dans le

lagon et 1100 à 2200 cellules par litre dans l’océan. Dans le lagon de Vairao

(Tahiti) les valeurs sont légèrement supérieures mais indiquent également une

plus forte densité par rapport à l’océan :

La majorité des cellules récoltées dans le lagon appartiennent aux diatomées

pennées et aux dinoflagellés cuirassés ou nus, ces deux groupes étant spécifique¬

ment très diversifiés. L’essentiel de la biomasse apparaît constitué de flagellés, en

particulier des Coccolithophoridés, et d’algues unicellulaires qui forment le

îannoplancton. Leur présence est mise en évidence par des mesures de produc¬

tivité primaire s’adressant à des échantillons d’eau filtrée ne contenant plus

^ue des cellules de dimensions inférieures à 30 /im : la productivité de ces

ellules représente 80% de l’activité photosynthétique totale (SOURNIA et

RICARD 1976).

. PARAMETRES PHYSICO-CHIMIQUES

Au cours des mois de juillet 1974 et août 1975, les valeurs des principaux

paramètres physico-chimiques ont été les suivantes :

T° (1)

S %o

NO 3 (2)

PO 4 (2)

Si0 4 (2)

O 2 dissous l 1 )

dans le lagon

24° à 26° C

36 à 38 %o

0.18 à 0.32

0.18 à 0.21

2.02 à 2.70

5.72 à 7.22 ml/l

- dans l’océan

25° à 26° C

35 %o

0.16

0.21

2.48

7.77 ml/l

(1) - Les valeurs de la température et de l’oxygène dissous sont les moyennes des valeurs mi¬

nimales et maximales relevées au cours de la période diurne.

(2) - les valeurs indiquées sont en /Jgr. at/litre de N 2 , P et Si pour les nitrates, phosphates et

silicates.

Source : MNHN. Paris

348

M. RICARD

IV. CONCLUSIONS

L’étude de la composition qualitative et quantitative des récoltes réalisées

dans le lagon de Tiahura (île de Moorea) met en évidence les faits suivants :

-la diversité spécifique des peuplements de diatomées contraste avec la pau¬

vreté numérique du microplancton et met en évidence le rôle prépondérant

du nannoplancton.

- les diatomées récoltées dans les lagons ont peu d’affinité avec le phytoplanc-

ton du large en raison de la prépondérance des formes benthiques : cette forte

opposition entre le phytoplancton de l’océan et le tychoplancton du lagon

caractérise, au même titre que la diversité spécifique, les lagons de Polynésie.

- le rôle de la barrière récifale est prépondérant car, suivant son extension et

l’importance du lagon qu’elle détermine, le pourcentage des diatomées plancto-

niques et benthiques reflète le degré des influences océaniques : à Tiahura

(Moorea) le lagon est moins développé qu’à Vairao (Tahiti) et les diatomées

planctoniques sont mieux représentées dans les récoltes du lagon.

- les taxons tropicaux endémiques sont peu nombreux par rapport aux taxons

cosmopolites ou tempérés tropicaux, mais leur taux semblerait constant dans les

récoltes côtières de l’océan Pacifique et de l’océan Indien.

BIBLIOGRAPHIE

ALLEN, W. E., 1937 — Plankton diatoms of the gulf of California obtained by the G. Allan

Hancock Expédition of 1936. Hancock Pacific Exp., Scripps Instit., Océanogr.3, 4 :

47-59.

ALLEN, W. E., 1938 - Id. Ibid. 3, 5 : 61-98, 15 pl.

ANGOT, M., 1961 — Vie et économie des mers tropicales. Payot Ed., Paris : 1-326, 26 fxg.

ANGOT, M., 1966 —Le phytoplancton de surface pendant l’année 1964 dans la baie

d’Ambaro près de Nossy-Be. Cah. ORSTOM , Océanogr. 3, 4 : 5-18.

CUPP, E. E., 1943 — Marine plankton diatoms of the west coast of North America. Bul.

Scripps Instit. Océanogr. 5, 1 :1-238, pl. 1-5, 168 text fig.

DESROZIERES, R., 1969 — Surface macrophytoplankton of the Pacific océan along the

Equator. Limnol. Océanogr. 14, 4 : 626-632.

GILMARTIN, M., et REVELANTE, N., 1974 - The «Island Mass» effect on the phyto

plankton and primary production of the Hawaian Islands. J. Exp. Marine Biol. Ecol.

16 :181-204.

HASLE, G. R., 1959 — A quantitative study of phytoplankton from the équatorial Pacific.

Deep-Sea Res. 6 : 38-59.

HASLE, G. R., 1960 — Phytoplankton and ciliate species from the tropical Pacific. Skr.

Norske Vid. Ak. Oslo, I : Mat. Naturv. Kl 2 : 1-50.

HENDEY, N. I., 1937 — The plankton diatoms of the Southern seas. Discovery Rep. 16

DIATOMÉES MARINES DE TIAHURA

349

1-151.

KARSTEN, G., 1907 — Das indische Phytoplankton nach dem Material der deutschen

Tiefsee-Expedition, 1898-99. Wiss. Ergebn. Dtsch. Tiefsee-Exp. «Valdivia», 1898-99,

II, 2 : 221-544, Taf. 35-54.

REYNAUD-BEAUVERIE, M. A., 1936 — Le milieu et la vie en commun des plantes.

Encyclopédie Biologique, P. Lechevallier Ed. : 1-237.

REYSSAC, J., 1966 a — Quelques données sur la composition et l’évolution annuelle du

phytoplancton au large d’Abidjan (mai 1964-mai 1965). ORSTOM, Doc. Scient, prov.

003 : 1-31.

REYSSAC, J., 1966 b —Diatomées et Dinoflagellés des eaux ivoiriennes pendant l’année

1965 .ORSTOM, Doc.Scient, prov. 010 :1-22.

RICARD, M., 1970 a — Premier inventaire des diatomées et des dinoflagellés du plancton

côtier de Tahiti. Cah. Pacif. 14 : 245-254, 2 pl.

RICARD, M., 1970 b - Observations sur les diatomées du genre Ethmodiscus Castracane.

Rev. Algol. N. S. X, 1 : 56-73, 4 pl.

RICARD, M., 1974 —Etude taxinomique des diatomées marines du lagon de Vairao.

I. Le genre Mastogloia. Rev. Algol., XI (1-2) : 161-178, 4 pl.

RICARD, M., 1975 a — Ultrastructure de quelques Mastogloia (diatomées benthiques)

marines d’un lagon de Tahiti. Protistologica XI, 1 : 49-60, 4 pl.

RICARD, M., 1975 b — Quelques diatomées nouvelles de Tahiti décrites en microscopie

photonique et électronique à balayage. Bull. Mus. Hist. Nat. Bot. 23, 326 : 201-229,

4 pl.

SILVA, E. S., 1956 — Contribuçao para o estudo do microplancton marinho de Mozam¬

bique./fa. Invest. Ultramar, Est. Ens. Doc. 28 : 1-97, pl. 1-14.

SILVA, E. S., 1960 — O microplancton de superficie nos meses de Setembro e Outubro na

estaçao de Inhaca (Mozambique). Trabhs Cent. Biol. pisc. Lisboa 28 :1-56, pl. 1-25.

SOURNIA, A., 1966 — Premier inventaire du phytoplancton littoral de l’île Maurice. BuL

Mus. Nat. Hist. Nat. Paris, 2e sér. 37, 6 : 1046-1050.

SOURNIA, A, 1968 a—Diatomées planctoniques du canal de Mozambique et de l’île

Maurice. Mém. ORSTOM 31 : 1-120, 13 pl.

iOURNIA, A., 1968 b — Quelques données nouvelles sur le phytoplancton marin et la

production primaire à Tuléar (Madagascar). Hydrobiologia 31, 3-4 : 545-560.

SOURNIA, A., 1969 — Cycle annuel du phytoplancton et de la production primaire dans les

mers tropicales. Marine Biol. 3, 4 : 287-303.

SOURNIA, A., 1970 — A checklist of planktonic diatoms and dinoflagellates from the

Mozambic channel. Bull. Mar. Sci. 20, 5 : 678-696.

SOURNIA, A., et RICARD, M., 1976 — Phytoplankton and its contribution to primary

productivity in two coral reef areas of French Polynesia. Micronesica 11, 2 :159-166.

STEEMANN-NIELSEN, E., 1939 — Die Ceratien des Indischen Ozeans. Dana Rep. 17 :

1-33.

SUBRAHMANYAN, R., 1946 — A systematic account of the marine plankton diatoms of

the Madras Coast .Proc. Indian Ac. Sc., sec. B 24, 4 : 85-197.

SUBRAHMANYAN, R., 1958 a — Phytoplankton organisms of the Arabian sea of the west

coast of India./. Indian Bot. Soc. 35, 4 : 431-441.

SUBRAHMANYAN, R., 1958 b — Ecological studies on the marine phytoplankton of the

west coast of India. Mem. Indian Bot. Soc. 1 : 145-151.

SUBRAHMANYAN, R., et SARMA, A. H. V., 1960 — Studies on the phytoplankton of

350

M. RICARD

the west coast of India. III. Seasonal variation of the phytoplankters and environmental

factors. Indian J. Fish. VII : 307-336.

TRAVERS, A., et TRAVERS, M., 1965 - Introduction à l’étude du phytoplancton et des

Tintinnides de la région de Tuléar (Madagascar). Rec. Tr. Stn. Mar. Endoume 26, 41 :

7-139.

UTERMOEHL, H., 1958 -Zur Vervollkommung der quantitativen Phytoplankton Metho-

dik. Mitt. Int. Ver. LimnoL 9 :1-38.

WOOD, E. J. F., 1961 a — Studies on Australian and New Zealand diatoms. IV. Descrip¬

tions of further sedentary species. Trans. R. Soc. N. Z. 88, 4 : 669-698, pl. 50-56.

WOOD, E. J. F., 1961 b —Id. V. The Rawson collection of recent diatoms. Ibid. 88, 4 :

699-712, pl. 50-56.

WOOD, E. J. F., 1963 a — Checklist of diatoms recorded from the Indian océan. CSIRO,

Div. Fisf. Oceanogr. Rep. 36 :1-311.

WOOD, E. J. F., 1963 b — Studies on Australian and New Zealand diatoms. VI. Tropical

and subtropical species. Trans. R. Soc. N. Z., Bot. 2, 15 :199-218, pl. 1-4.

DIATOMÉES MARINES DE TLAHURA

351

ANNEXE : LISTE DES TAXONS RÉCOLTÉS A TIAHURA

Diatomées Centriques Distribution Répartition

Lagon

Océan

Mondiale

Actinocyclus ehrenbergii Ralfs

Actinocyclus ehrenbergii var. tenella (Breb.) Hust.

Actinocyclus subtilis (Greg.) Ralfs

Actinoptychus senarius (Ehr.) Ehr.

Actinoptychus splendens (Shadb.) Ralfs

Actinoptychus undulatus (Bailey) Ralfs

Arachnoidiscus ehrenbergii Bailey ex Ehr.

T, t

Asterolampra marylandica Ehr.

T, t

Aulacodiscus kittoni var. africana (Cottam) Rattray

T, te

Auliscus coelatus Bailey

T, te

Auliscus sculptus (Wm. Smith) Ralfs

T, t

Bacteriastrum delicatulum Cleve

T, t

Biddulphia aurita (Lyngb.) Bréb.ex Goddart

Biddulphia pulchella Gray

T, t

Biddulphia reticulata Roper

T, te

Biddulphia rhombus (Ehr.) Wm. Smith

Biddulphia titiana (Grunow) Grunow

T, te

Biddulphia tuomeyi (Bailey) Roper

Cerataulus turgidus (Ehr.) Ehr.

T, t

Ghaetoceros atlanticum Cleve

Chaetoceros compressum Lauder

Chaetoceros curvisetum Cleve

Chaetoceros messanense Castracane

T, te

Chaetoceros peruvianum Brightwell

Chrysanthemodiscus floriatus Mann

T, te

Climacodinium frauenfeldianum Grunow

T, te

Corethron criophilum Castracane

Coscinodiscus centralis Ehr.

Coscinodiscus centralis var. pacificus Gran & Angst

T, t

Coscinodiscus concavus Ehr.

T, te

Coscinodiscus excentricus Ehr.

Coscinodiscus jonesianus (Grev.) Ostenfeld

T, t

Coscinodiscus marginatus Ehr.

Coscinodiscus nitidus Gregory

Coscinodiscus nodulifer A. Schmidt

Cyclotella meneghiniana Kützing

Ditylum brightwelli (West) Grunow

T, t

Ethmodiscus appendiculatus (Grunow) Ricard

Ethmodiscus gazellae (Janish) Hustedt

T, t

Endictya oceanica Ehr.

Fréquences dans le lagon (col. 1) et dans l’océan

R : rare; (-) : absent.

(col. 2) : TF

: très fréquent; F : fréquent;

Répartition mondiale (col. 3) : C : cosmopolite; T : intertropical; t : tempéré; te : tempéré

chaud; tf : tempéré froid; A : arctique et/ou antarctique.

352

M. RICARD

Eucampia zoodiacus Ehr.

Hemiaulus hauckii Grunow R

Hemiaulus sinensis GreviUe F

Hemidiscus cuneiformis Rattray F

Hyalodiscus laevis Ehr. R

Leptocylindrus danicus Cleve R

Melosira dubia Kützing R

Melosira sol (Ehr.) Kützing R

Planktoniella sol (Wallich) Schütt

Podosira hormoides (Montagne) Kützing

Podosira stelliger (Bailey) Mann F

Rhizosolenia alata Brightwell/a alata R

Rhizosolenia hebetatafa semispina (Hensen) Gran R

Rhizosolenia imbricata Brightwell/a imbricata F

Rhizosolenia imbricata var. shrubsolei (Cleve) Schrôder F

Rhizosolenia setigera Brightwell R

Thalassiosira excentrica Cleve R

Thalassiosira hyalina (Grunow) Gran F

Triceratium alternans Bailey R

Triceratium calvescens Castracane TF

Triceratium dubium Brightwell F

Triceratium favus fa quadrata Grunow

Triceratium formosum Brightwell fa formosum TF

Triceratium formosum fa quadrangulare (Greville)

Hustedt F

Triceratium réticulum fa hexagonale Ricard F

Triceratium shadboltianum Greville TF

Triceratium spinosum Bailey F

Diatomées pennées

Achnanthes brevipes Agarth F

Achnanthes brevipes var. angustata (Kütz.) Cleve F

Achnanthes citronella (Mann) Hustedt R

Achnanthes longipes Agardh R

Achnanthes rhombica Oestrup TF

Amphiprora alata (Ehr.) Kützing F

Amphiproragigantea vai.sulcata (O’Meara) Cleve R

Amphora acuta var. arcuata (A. Schmidt) Cleve F

Amphora angularis Gregory F

Amphora angustata var. ventricosa (Gregory) Cleve F

Amphora bigibba Grunow R

Amphora cingulata Cleve F

Amphora coffeaeformis (Agardh) Kützing F

Amphora crassa Gregory var. crassa F

Amphora dubia Gregory F

Amphora egregia Ehr. R

Amphora exigua Gregory R

Amphora granulata var. bigibbosa Ricard R

Amphora mexicana A. Schmidt var. mexicana TF

Amphora obtusa Gregory var. obtusa TF

T, t

T, te

T, t

T, te

T, t

T, te

T, t

T, te

T, t

T, te

T, t

T, te

T, t

Source: MNHN, Paris

DIATOMÉES MARINES DE TIAHURA

353

Amphora obtusa var. rectangubta Peragallo F

Amphora ostrearia Bréb. ex Kütz. var. ostrearia F

Amphora staurophora (Castracane) Cleve R

Asterionella glacialis Castracane F

Asterionella notata Grunow R

Auricula complexa (Gregory) Cleve F

A uricula insecta (Grunow) Cleve F

Bacillaria paradoxa Gmelin F

C aloneis bacillum (Grunow) Meereschkowsky R

Cabneis liber (Wm Smith) Cleve F

Cabneis silicub (Ehr.) Cleve R

Campylodiscus biangubtus Grevilla R

Campybdiscus incertus A. Schmidt TF

Campybdiscus innominatus Ross et Abdin F

Campybdiscus btus Shadbolt TF

Campybdiscus ralfsii Wm Smith F

Campybdiscus wallichianus Greville F

Climacosphenia elongata Bailey F

Climacosphenia moniligera Ehr. TF

Cocconeis britannica Naegeli TF

Cocconeis heteroidea Hantzsch var. heteroidea TF

Cocconeis pellucida Hantzsch TF

Cocconeis pbcentub Ehr. var .pbcentub F

Cocconeis scutellum Ehr. var. scutellum R

Cocconeis vairaensis Ricard TF

Cylindrotheca cbsterium (Ehr) Reiman et Lewin TF

Oimeregramma dubium (Grunow) Grunow TF

Dimeregramma minor (Gregory) Ralfs F

Dipbneis bomboides (A. Schmidt) Cleve TF

Diploneis bombus Ehr. var. bombus TF

Dipbneis chersonensis (Grunow) Cleve F

Dipbneis crabro (Ehr.) Ehr. var. crabro F

Dipbneis coffaeiformis (A. Schmidt) Cleve TF

Dipbneis debyi (A. Schmidt) Cleve F

Dipbneis fusca (Gregory) Cleve var .fusca F

Diploneis smithii (Bréb.) Cleve TF

Dipbneis suborbicubris (Gregory) Cleve R

Dipbneis vacilbns var. renitens (A. Schmidt) Cleve R

Grammatophora gibberub Kützing R

Grammatophora hamulifera Kützing TF

Grammatophora oceanica Ehr. var. oceanica TF

Grammatophora undubta Ehr. F

Gyrosigma balticum (Ehr.) Rabenhorst TF

Gyrosigma ebgans Ricard TF

Gyrosigma infbtum Ricard TF

Gyrosigma gibbosum Ricard TF

Gyrosigma spenceri (Wm Smith) Griffith et Henfrey F

Hydrosilicon mitra Brun F

Licmophora ehrenbergii (Kütz.) Grunow F

Licmophora ehrenbergii fa angustata (Grun.) Grun. F

Licmophora mediterranea Meereschkowsky R

T, te

T, t

T, te

T, t

T, te

T, t

T, te

T, t

T,t

T, t

t, A

Source : MNHN, Paris

354

M. RICARD

Licmosphenia clevei Meereschkowsky R

Licmosphenia peragalli Meereschkowsky R

Mastogloia achnanthiodes Mann F

Mastogloia affirmata (Leuduger et Fortmorel) Cleve R

Mastogloia aspera var. crassa Ricard F

Mastogloia asperuloides var. angustatissima Ricard F

Mastogloia baldjickiana Grunow TF

Mastogloia binotata (Grunow) Cleve TF

Mastogloia citrus Cleve TF

Mastogloia composita Voigt F

Mastogloia corsicana Grunow TF

Mastogloia decussata Grunow F

Mastogloia erythrea Grunow F

Mastogloia fimbriata (Brightwell) Cleve TF

Mastogloia horvathiana Grunow TF

Mastogloia inaequalis Cleve F

Mastogloia kjelmanii Cleve F

Mastogloia punctatissima (Greville) Ricard R

Mastogloia quinquecostata Grunow F

Mastogloia schmidtii Heiden et Kolbe R

Mastogloia undulata Grunow F

Navicula clavata Gregory F

Navicula cancellata Donkin R

Navicula cryptocephala Kützing var. cryptocephala F

Navicula cyprinus (Wm Smith) Boyer TF

Navicula directa var. remota Cleve F

Navicula granulata Bailey TF

Navicula grevilleoides Hustedt F

Navicula longa (Gregory) Ralfs TF

Navicula lyra fa typica A. Schmidt R

Navicula lyroides Hendey F

Navicula marina Ralfs F

Navicula perobesa A. Schmidt TF

Navicula perrhombus Hustedt F

Navicula plicatula Grunow F

Navicula pseudony Hustedt F

Navicula rhombica Gregory R

Navicula robertsiana fa typica Hustedt TF

Nitzschia acuta Cleve R

Nitzschia amphibia Grunow R

Nitzschia angularis Wm Smith F

Nitzschia constricta var. bombiformis Grunow TF

Nitzschia delicatissima Cleve F

Nitzschia distans Gregory F

Nitzschia graeffii Grunow F

Nitzschia majuscula Grunow TF

Nitzschia maxima Grunow F

Nitzschia panduriformis Gregory F

Nitzschia seriata Cleve R

Nitzschia sigma (Kütz.) Wm. Smith var. sigma F

Nitzschia sigma var. intercedens Grunow F

T, t

T, te

T, t

T, te

T, t

T, te

t, A

T, te

T, t

T, te

T, t

T, te

T, t

Source : MNHN. Paris

DIATOMÉES MARINES DE TIAHURA

355

Nitzschia spathulata Brébisson F

Nitzschia ventricosa Palmer TF

Opephora pacifica (Grunow) Petit F

Plagiogramma atomus Greville F

Plagiogramma interruptum (Gregory) Ralfs R

Plagiogramma staurophorum (Greg.) Heiberg TF

Pleurosigma angulatum (Quekett) Wm Smith F

Pleurosigma décorum Wm Smith R

Pleurosigma formosum Wm Smith F

Pleurosigma itium Ricard R

Pleurosigma longum Cleve F

Pleurosigma rigidum Wm Smith TF

Pleurosigma tahitianum Ricard R

Podocystis adriatica (Kütz.) Ralfs R

Podocystis spathulata (Shadbolt) Van Heurck TF

Progonaia musca (Gregory) Schrader F

Pseudoeunotia doliolus (Wallich) Grunow R

Rhabdonema adriaticum Kützing TF

Rhabdonema punctatum (Harvey et Bailey) Stodder

ex Boyer R

Rhaphoneis amphiceros var. tetragona Grunow F

Rhoicosigma antillarum Cleve TF

Sceptroneis peragalli (Leud et Fort.) Meister F

Stauroneis polynesiae (Brun) Hustedt TF

Stauroneis salina Wm Smith F

Surirella fastuosa Ehr. . fastuosa TF

Surirella fastuosa var. cuneata (A. Schmidt) Per. TF

Surirella martensiana (Grun.) Peragallo F

Surirella reniformis Peragallo F

Synedra crystallina (Ag.) Kütz. var. crystallina TF

Synedra laevigata Grunow var. laevigata TF

Synedra robusta Ralfs R

Synedra ulna (Nitzsch) Ehr. F

Synedra undulata Bailey TF

Synedrospheniagomphonema (Jan. et Rab.) Hustedt F

Thalassionema nitzschioides Grunow R

Thalassiotrix frauenfeldii Grunow

Thalassiotrix mediterranea var. pacifica Cupp

Trachyneis aspera (Ehr.) Cleve var. aspera TF

Trachyneis velatoides Ricard F

Tropidoneis lepidoptera (Greg.) Cl. var. lepidoptera TF

Tropidoneis maxima var. subalata Cleve F

Tropidoneis maxima (Gregory) Cleve TF

T, te

t, A

T, t

T, te

T, t

T, te

T, t

T,t

Source : MNHN, Paris

357

ANALYSES BIBLIOGRAPHIQUES

P. BOURRELLY

BOURRE LLY, P. - Quelques algues d’eau douce de Guinée. Bull. Mus. Nat.

Hist. Nat. 3e sér., n° 276, Bot. 20 : 1-72, 11 pl.

L’étude de quelques récoltes de Guinée permet de reconnaître 220 taxons

d’algues d’eau douce (Diatomées exclues). Les Desmidiées, avec 144 taxons sont

les formes dominantes. Cinq nouveautés des genres Euastrum, Micrasterias, Stau-

rodesmus, et Staurastrum sont décrites. L’élément tropical est représenté par 80

taxons. Des notes de systématique critique et une abondante iconographie com¬

plètent ce travail.

CASPER, S.J. - Grundzüge eines natürlichen Systems der Mikroorganismen. G.

Fischer Ed., Iena, 1974, 1 vol., 1-232, 42 fig., 34 tabl.

Dans ce volume d’une conception très originale, l’auteur fait une synthèse de

nos connaissances sur les organismes microscopiques végétaux et animaux : c’est-

à-dire les Bactéries, les Algues, les Champignons, les flagellés incolores, les Proto¬

zoaires. Il étudie 28 exemples types et s’attache particulièrement à l’ultrastructu-

re des flagelles et à la cytologie fine des organismes.

Il aboutit ainsi à une classification très proche de celle qui est actuellement

admise mais avec une terminologie de Zoologiste, et non de Botaniste.

Ce livre, sous une forme réduite, présente une documentation extraordinaire.

La bibliographie occupe 26 pages, elle est très complète, avec cependant quel¬

ques petites lacunes sur les procaryotes. Même si on ne partage pas les concep¬

tions de l’auteur, cet ouvrage rendra de grands services : c’est une véritable mine

de renseignements. Citons particulièrement les 34 tableaux qui résument, de fa¬

çon très didactique, les caractères des Microorganismes (pigments, réserves, types

des plastes, type de flagelles, etc...).

Grâce à cet ouvrage, le lecteur aura une vue d’ensemble très précise sur le

monde microscopique et il faut remercier son auteur de nous faire part de son

érudition.

COR1LLION, R. - Flore des Charophytes (Characées) du Massif Armoricain et

des contrées voisines d’Europe occidentale. In Flore et Végétation du Massif

Armoricain, Jouve Ed., Paris, 1975, t. IV, 1 vol. : 1-216, 18 cartes, 16 pl.

Ce volume soigneusement présenté fait partie de la Flore du Massif Armori¬

cain préparée par H. des ABBAYES. Le Massif Armoricain renferme 15 especes

Source : MNHN, Paris

358

BIBLIOGRAPHIE

de Chara, 1 de Lamprothamnion, 1 de Nitellopsis, 10 de Nitella et 6 de Toly-

pella.

De plus l’auteur décrit en appendice les Characées françaises non rencontrées

en Bretagne (1 de Lychothamnus, 1 Nitella, 1 Tolypella) : ainsi le lecteur a, sous

un format pratique, une véritable flore des Charophytes de France. L’ouvrage

n’est d’ailleurs pas simplement une flore, mais une étude simple et très complète

de ces algues. Une trentaine de pages est consacrée aux généralités : écologie, dis¬

tribution géographique, morphologie, cytologie. Les lecteurs non spécialistes ap¬

précieront le glossaire des termes descriptifs particuliers aux Characées. 18 cartes

montrent la distribution des taxons dans le Massif Armoricain. La partie analyti¬

que des espèces, avec des clefs de détermination, figures abondantes, variétés,

écologie, constitue en 120 pages le corps de l’ouvrage. Le lecteur trouvera des

renseignements précis sur le nombre chromosomique, un tableau des caractères

comparés des organes reproducteurs, un abrégé phylogénétique, un historique,

etc.

Cette rapide énumération montre l’intérêt de cet ouvrage, qui est à la fois

simple, précis et complet. Sa présentation très claire, ses illustrations originales,

en font un instrument de travail fort pratique qui fait honneur à son auteur, et

qui permettra à tous les botanistes, même non spécialisés, de pouvoir déterminer

toutes les Characées de la Flore française.

CORILLION, R. et GUERLESQUIN, M. — Recherches sur les Charophycées

d’Afrique occidentale, systématique, phytogéographie et écologie, cytologie,

Bull. Soc. Sc. Bretagne 1972, 47 : 1-169, 18 pl. 23 phot.

Ce mémoire étudie les Characées de Mauritanie, Sénégal, Mali, Côte d’ivoire,

Guinée, Togo et Ghana. Il est composé de trois parties : Systématique, Ecologie

et Phytogéographie, Cytologie.

Dans le chapitre systématique nous trouvons 15 taxons de Chara, et 15 de

Nitella (dont une nouvelle espèce). Toutes les unités systématiques sont décrites

en détail et l’illustration originale est abondante (8 planches et 23 photos).

Dans ce chapitre figurent aussi des précisions sur l’écologie, la phytosociologie

et la distribution géographique. Des clefs de détermination très précises complè¬

tent cette mise au point.

La deuxième partie traite de la phytogéographie et de l’écologie et présente

les associations intertropicales des Characées africaines et leur relation avec les

autres groupements d’hydrophytes. 22 cartes montrent les répartitions africaines

et mondiales des espèces les plus remarquables.

La dernière partie est une étude des nombres chromosomiques de 9 taxons de

Nitella et de 2 de Chara accompagnée de 10 planches et de 3 cartes de réparti¬

tion géographique des diverses lignées chromosomiques.

Une bibliographie très complète, un index, un vocabulaire terminent ce tra¬

vail.

L un des auteurs, R. CORILLION, a déjà publié un ouvrage désormais classi¬

que : «Les Charophycées de France et d’Europe occidentale». Le présent mémoi¬

re le complète en quelque sorte, en l’étendant sur une partie de l’Afrique dont la

végétation charologique était mal connue.

BIBLIOGRAPHIE

359

DROUET, Fr. - Révision of the Nostocaceae with cylindrical trichome (forme-

ly Scytonemataceae and Rivulariaceae). Hafner Press, 1973 : 1-292, 83 fig.

Voici le troisième ouvrage monographique de l’auteur sur les Cyanophycées,

ouvrage encore plus explosif et plus déroutant que les précédents.

Il étudie ici les Nostocales des familles des Scytonematacées, Rivulariacées et

Microchaetacées, et quelques genres des Borzinématacées à trichomes non toru-

leux.

Pour l’auteur, forme du thalle, type de ramification, présence ou absence de

gaines ou d’hétérocystes, sont des caractères sans valeur systématique et sous l’u¬

nique dépendance des conditions du milieu. Le seul critère valable est donné par

la forme de la cellule végétative terminant le trichome. Les coupures génériques

se font ainsi :

1) cellule terminale hémisphérique devenant presque sphérique : Scytonema.

2) cellule terminale d’abord hémisphérique puis conique, obtuse ou cylindrique

à pointe arrondie : Calothrix.

3) cellule terminale d’abord hémisphérique puis plus ou moins conique aigüe :

Raphidiopsis.

Ainsi ce grand ensemble qui groupait jusqu’alors 15 genres et près de 300 es¬

pèces est réduit à 3 genres et 4 espèces.

Le genre monospécifique Scytonema tel qu’il est défini renfermera sous le

nom unique de Scytonema hofmannii aussi bien les Scytonema vrais que les To-

lypothrix, Plectonema sans hétérocyste, les Desmonema, et même les Handeliella

à ramification véritable du type Stigonema. Par contre Scytonematopsis est pla¬

cé dans les Calothrix. Le genre Calothrix avec deux espèces, l’une pour les eaux

douces (C. parietina) et l’autre (C. crustacea) pour les eaux marines, groupe Ri¬

vularia, Aphanizomenon, Microchaete, Aulosira, Homeothrix, Gloeotrichia etc...

Ainsi Rivularia haematites, Gloeotrichia natans, Homeothrix juliana et Anabaena

unispora par exemple appartiennent tous à l’espèce Calothrix parietina. De mê¬

me tous les Rivularia marins, Microchaete grisea, Richelia intracellularis et Kyr-

tuthrix dalmatica portent le même nom de Calothrix crustacea. Quant au genre

monospécifique Raphidiopsis il s’accroît des Anabaenopsis à hétérocystes api¬

caux terminaux coniques et des Aphanizomenon à apex très effilés car l’auteur

indique dans sa diagnose la présence d’hétérocyste, caractère non signale par

FRITSCH et RICH, inventeurs du genre.

L’ensemble de ce travail, solidement documenté par une investigation très

poussée des échantillons d’herbiers du monde entier, bouleverse entièrement la

systématique classique. Malheureusement, à notre avis, il est fondé non sur une

expérimentation convaincante, mais sur le postulat des «écophènes» qu’il faut

accepter sans preuves réelles. Nous n’ignorons pas l’importance du polymor¬

phisme des Cyanophycées et de ses relations avec le milieu, cependant nous n’ad¬

mettons pas sans preuves suffisantes les conclusions de l’auteur pour qui tout est

écophène. Ainsi il est impossible d’admettre que Aphanizomenon flos aquae soit

un Microcoleus vaginatus et que sa variété gracile soit un Calothrix parietina. De

même il est curieux que Microchaete tenera soit un Scytonema tandis que M. gri¬

sea et M. diplosiphon sont deux Calothrix.

Enfin du point de vue nomenclatural nous comprenons mal pourquoi le nom

360

BIBLIOGRAPHIE

Calothrix Agardh 1824 est préféré à celui de Rivularia Roth. 1797 (ou mieux

1802-1806). De même le type de Scytonema nous semble être 5c. myochrous

(Dillwyn 1802) Agardh 1812 et non hofmannii Agardh 1817.

A notre grand regret, nous ne pouvons accepter cette nouvelle nomenclature

qui par sa simplification excessive et arbitraire conduit à donner le même nom à

des organismes très différents et de ce fait rend impossible toute étude floristi¬

que ou écologique. Malgré ces critiques, cet ouvrage rendra de grands services par

sa bibliographie et son index particulièrement exhaustif.

GAYRAL, P. — Les algues, morphologie, cytologie, reproduction, écologie.

Doin Ed., Paris, 1975 : 1-166, 84 fig.

Cet ouvrage, destiné aux étudiants, est un modèle de clarté et de précision.

Dans un texte relativement court, l’auteur fait une synthèse de nos connaissances

sur le grand monde des algues.

Le plan suivi : 1) généralités, avec morphologie, cytologie et reproduction.

2) caractères des grands groupes d’algues.

3) quelques aspects de l’écologie et de la physiologie des algues :

phytoplancton et algues non planctoniques.

montre bien que tout le domaine de l’algologie est abordé.

Un glossaire, un index alphabétique, un tableau synoptique des algues (jus¬

qu’à l’ordre), de nombreux schémas, en font un travail d’une haute valeur, tant

pédagogique que scientifique.

Ce livre qui rendra de grands services aux étudiants et à leurs maîtres, intéres¬

sera aussi les algologues spécialisés car il donne une vue d’ensemble moderne et

bien documentée sur les algues qu’elles soient micro- ou macroscopiques, marines

ou dulçaquicoles.

Cet ouvrage démontre de façon très nette qu’on peut être à la fois bon cher¬

cheur et excellent professeur.

KALBE, L. — Kieselalgen’ in Binnengewàssern. Die neue Brehm Bücherei, 1973

467 :1-206, 37 pl.

L’auteur, diatomiste bien connu, nous donne un petit livre sur les Diatomées

d’eau douce qui est une synthèse très complète de nos connaissances sur ces al¬

gues.

La moitié du livre est consacrée à la structure, la reproduction et l’écologie

des Diatomées. Tous les problèmes posés par l’étude de ces organismes sont

traités, brièvement, mais avec précision. Nous y trouvons aussi bien des rensei¬

gnements sur la préparation, le montage des Diatomées que sur le dessin, la

microphotographie ou le comptage.' La partie écologique de 50 pages renferme

des listes d’espèces caractéristiques hallobiontes et saprobiontes.

La dernière partie donne, suivant la systématique classique, une brève diagno¬

se de chaque genre de Diatomées et est complétée par 465 figures groupées en

37 planches représentant les formes les plus communes. Pour chaque figure, le

nom d’espèce est accompagné de renseignements écologiques. Chaque chapitre

possède une bibliographie très complète. Le livre se termine par un double in¬

dex : matière et noms des espèces.

En conclusion un petit volume, bien documenté, bien présenté, qui est une

BIBLIOGRAPHIE

361

excellente initiation à la connaissance des Diatomées dulçaquicoles.

KOMAREK, J. - The morphology and taxonomy of Crucigenioid algae (Scene-

desmaceae, Chlorococcales). Arch. Protistensk. 1974, 116 : 1-75.

L’auteur présente une étude des Chlorococcales autosporées à cénobes plats

fondée sur le mode de division lors de la formation des autospores.

Grâce à de nombreuses cultures et à l’étude du matériel sauvage, l’auteur re¬

connaît deux grands types de division : 1 - l’orientation de la croix dessinée par

les 4 autospores est identique à celle des 4 cellules du cénobe paternel. 2 - l’o¬

rientation de cette croix lors de l’autosporulation fait un angle de 45 avec les

branches de la croix formée par les cellules du cénobe paternel. Dans le premier

type se place les genres : Tetrastrum, Crucigeniella, Willea, Westella et Tetrachlo-

rella. Dans le deuxième type on trouve : Crucigenia et Hofmania.

L’auteur donne une étude monographique de tous ces genres et une descrip¬

tion de toutes les espèces. Le genre Crucigeniella Lemm. est repris pour les an¬

ciennes espèces Crucigenia rectangularis, lunaris, truncata, apiculata, pulchra,

crucifera et neglecta. De même le genre Willea Schmidle est ressuscité pour Cru¬

cigenia irregularis Wille et Dispora vilheimii Fott. Cet intéressant mémoire pré¬

sente de nombreuses nouvelles combinaisons et donne un aperçu sur la phylogé¬

nie possible de la famille des Scenedesmacées. Une très importante illustration de

102 figures complète cette belle monographie.

LEE, K.W. et BOLD, H.C. - Phycological studies 12. Characium and some Cha-

racium like Algae. Texas Publ. 1974, 7403,: 1-127.

Ce travail très intéressant est fondé sur des cultures d’algues. Les auteurs y

étudient 10 espèces de Characium (dont 8 nouvelles espèces) une nouvelle espèce

de Pseudocharacium à zoospore quadriflagellée, une nov. sp. d'Ankyra à trois

épines, parmi les algues vertes chlorococcales. De plus une Tétrasporale, nouvelle

espèce de Characiochloris , est décrite. Enfin, les auteurs donnent quelques com¬

pléments sur deux Xanthophycées des genres Characiopsis et Pseudocharaciopsis.

Pour chacune de ces espèces on trouve une étude morphologique et taxino¬

mique accompagnée d’une étude physiologique portant surtout sur la nutrition

de ces algues. Signalons aussi le chapitre sur la fixation des zoospores qui montre

que chez quelques espèces de Characium , la zoospore se fixe non par le pôle api¬

cal, mais par le pôle postérieur, après rotation de la cellule accrochée d’abord

par ses flagelles.

L’illustration, très abondante, comprend 223 figures. Malheureusement il s’a¬

git le plus souvent de photographies qui ne permettent pas, comme un bon des¬

sin, d’avoir une idée précise de la morphologie de ces algues.

MARGALEF, R. — Ecologia. Oméga Ed., Barcelona, 1974 : VII-XV, 1-951.

Voilà un livre impressionnant par son volume et par l’ampleur du sujet :

l’écologie. Après un rappel historique sur la naissance de cette discipline, l’auteur

traite l’écologie sous tous ses aspects dans sept chapitres consacrés au milieu, à la

biogéographie, à l’écologie descriptive, à l’écologie trophique, à l’écologie démo¬

graphique, à l’écosystème dans le temps et à l’écosystème dans l’espace. L’ou¬

vrage se termine par un chapitre de synthèse dans lequel l’auteur donne une con¬

clusion pour chacun des chapitres précédents. Chaque chapitre est abondamment

362

BIBLIOGRAPHIE

illustré de planches et de graphiques et se termine par une bibliographie très

complète.

Cet ouvrage est certainement le plus intéressant et le plus complet de tous

ceux qui ont été consacrés, à ce jour, à l’écologie et sera par conséquent d’une

aide précieuse aussi bien aux écologistes avertis que débutants.

MOLLENHAUER, D. — Erstes Internationales Desmidiaceensymposium, Bieber

(Spessart) Sept. 1971. Beih.Nov. Hedwigia 1975, 42 : 1-316.

L’auteur a organisé le premier symposium international sur les Desmidiales, et

il nous présente les comptes-rendus de cette réunion qui groupait 17 spécialistes.

Tous les sujets ont été abordés : nomenclature (ANDRESEN, BICUDO), cycle

de vie (BIEBEL), cytologie et ultrastructure (CHARDARD, DOBBERSTEIN,

GERRATH), sexualité (DUBOIS-TYLSKI, KIES, LENZENWEGER, LIPPERT,

GERRATH), caryologie (KASPRIK), rapport entre ultrastructure des membra¬

nes et systématique (MIX), polymorphisme et systématique (RUZICKA) cultu¬

res synchrones (SCHULLE), sociologie et écologie (TASSIGNY), formation des

Chlamydospores (LHOSTKY). L’organisateur, après une introduction rappelant

le vaste champ d’études offert par les Desmidiées, donne une communication

très documentée sur la phylogénie des Zygnématales. Ce coup d’oeil trop rapide,

suffira cependant à montrer l’intérêt et la richesse de ce beau volume soigneuse¬

ment illustré. Espérons et souhaitons que ce premier symposium aura une des¬

cendance nombreuse et remercions MOLLENHAUER de son initiative.

NOVA SCOTIA RESEARCH FOUNDATION - Selected bibliography on algae.

Nov. Scotia res. Found. Darthmouth 1973, 14 : 1-200.

Voici, malheureusement, le dernier fascicule de cette intéressante publication

bien connue de nos lecteurs. Ce dépouillement bibliographique est fort bien fait,

les travaux principaux y sont cités et signalons la part importante qui est don¬

née à la «pratique», cultures des algues, utilisations médicales, alimentaires, in¬

dustrielles, etc... dont la bibliographie est souvent négligée.

STARMACH, K. — Cryptophyceae, Dinophyceae, Raphidophyceae. Flora Slod-

kowdna Polski 1974, 4 :1-519.

Voici le 12e volume de l’œuvre monumentale du Pr. STARMACH. Il offre les

mêmes qualités de présentation et de clarté que les précédents. Dans les trois

grands groupes étudiés, une série de clefs dichotomiques permet d’arriver à l’es¬

pèce. Pour chaque espèce la diagnose est complétée par une ou plusieurs figures

et par la répartition géographique. Une bibliographie accompagne chaque grou¬

pe. La systématique suivie est celle de notre ouvrage (Algues d’eau douce, 3,

1970).

Signalons que l’auteur indique quelques espèces de la Baltique (parmi les Di-

nophycées). L’illustration très abondante, 643 figures, rendra de grands services

au lecteur ignorant la langue polonaise.

TUPA, D.D. — An investigation of certain Chaetophoralen Algae. Beih. Nov.

Hedwigia 1974, 46 :1-V, 1-155, 291 fig.

Cet important travail est consacré à la systématique de certaines Chlorophy-

cées Chaetophorales d’eau douce. L’auteur, uniquement à l’aide de cultures, é-

Source : MNHN, Paris

BIBLIOGRAPHIE

363

tudie de nombreuses espèces des sept genres suivants : Protoderma, Gongrosira,

Pleurastrum, Microthamnion, Pseudendoclonium, Chamaetrichon et Aphano-

chaete. Il s’agit d’algues épiphytes ayant toutes, à l’exception de Microthamnion,

un thalle prostré à leur base. Une série de tableaux met en évidence les caractères

taxinomiques de tous les genres de Chaetophorales ainsi qu’une analyse histori¬

que critique.

L’auteur, avec PRINTZ, place les espèces dulçaquicoles d 'Ulvella parmi le

genre Protoderma. De même le genre Pleurothamnion Borzi est donné comme

synonyme de Gongrosira. Le genre Pleurastrum, très proche de Gongrosira, dont

seul l’aspect piriforme de la zoospore l’en sépare, groupe entre autres les Lepto-

sira à pyrénoïde et le Rheximena paucicellulare. Le nouveau genre monospécifi¬

que, Chamaetrichon, à thalle entièrement prostré, possède des zoospores quadri-

flagellées : c’est la grande différence avec Protoderma. Une étude physiologique

termine ce mémoire.

Ce travail bien documenté rendra de grands services aux systématiciens : l’il¬

lustration photographique, fondée sur des cultures, est fort intéressante, mais il

est dommage qu’elle ne soit pas complétée par une documentation sur le maté¬

riel «sauvage».

vVUTHRICH, M. — Contribution à la connaissance de la flore algologique du

Parc National Suisse : Les Diatomées. Resuit. Rech. Sc. Parc Nat. Suisse

1975, 14,72 :273-369.

Comme le remarque, avec ironie, l’auteur, le guide scientifique du Parc Natio-

îal Suisse (1966) indique que 558 plantes sont connues dans ce parc, avec seule-

nent une dizaine d’espèces d’algues; le guide ajoute : «Si l’on compare la flore

les algues du Parc avec celle des plantes à fleurs, la différence la plus frappante

éside dans le nombre restreint des espèces composant la première, dont quel¬

ques unes seulement ont été citées, comparée à la grande richesse en espèces des

ihanérogames de la région...». L’auteur, après étude d’un petit nombre de sta-

ions, signale, simplement pour les Diatomées, 468 taxons répartis en 36 genres,

îlle décrit 4 taxons nouveaux appartenant aux genres Achnantes, Anomoeoneis

:t Pinnularia. 41 plantes groupant plus de 450 dessins originaux illustrent ce

>eau travail. Le lecteur y trouvera des remarques de systématique critique et des

îotes sur l’écologie et la chimie des eaux. Un beau mémoire dont la finesse des

igures comblera d’aise les Diatomistes.

/ACUBSON, S. — Catalogo e iconografia de las Chlorophyta de Venezuela. Bol.

Centr. investig. biol. Univ. Zulia 1974, 11 : 1-143.

L’auteur qui a déjà publié un catalogue des Cyanophytes du Vénézuéla, (voir

Zev. Alg. XI, 1/2 : 202), nous donne aujourd’hui, avec une illustration de 436 fi¬

gures groupées en 31 planches, la catalogue des 434 Chlorophycées d’eau douce

signalées dans son pays. Les Desmidiacées s’y taillent la part du lion et y occu¬

pent 35 pages du texte et 22 planches. Pour chaque espèce, figure une illustra¬

tion et le lieu des récoltes, ainsi que les auteurs qui ont signalé l’espèce.

Ce travail rassemble ainsi, sous un faible volume, toute l’iconographie consa¬

crée aux Chlorophycées du Vénézuéla. Un excellent ouvrage qui permettra main¬

tenant de prospecter en profondeur ces eaux si riches en algues.

364

BIBLIOGRAPHIE

KOMAREK, J. — Taxonomie review of the généra Synechocystis Sauv. 1892,

Synechococcus Nâg. 1849 and Cyanothece gen. nov. (Cyanophyceae). Arch.

Protistenk. 1976, 118 : 119-179.

A l’aide de matériel «sauvage» pris dans la nature et de culture l’auteur étudie

3 genres de Chroococcales unicellulaires, solitaires le plus souvent. La forme des

cellules et le processus de division permet de séparer :

1 -Synechocystis à cellules globuleuses solitaires se divisant successivement

suivant deux plans perpendiculaires (comme chez Merismopedia).

2 - Synechococcus à cellules allongées, ellipsoïdales ou cylindriques se divisant

toujours par un plan perpendiculaire au grand axe en cellules filles souvent de

taille inégale.

3 - Cyanothece, nouveau genre créé pour les cellules ellipsoïdales, presque glo¬

buleuses, toujours solitaires et se divisant toujours en 2 cellules filles identiques

et suivant un plan perpendiculaire au grand axe.

Synechocystis groupe 17 espèces.

Les genres Rhabdoderma Schm. et Lauterb., Raciborskia Koczw., Romeria

Koczw., Amalia De Toni, Chroobacter Pringsh. et Lauterbomia Pringsh. sont

placés dans le genre Synechococcus Nâg. qui renferme 39 espèces dont certaines

forment de courts filaments irréguliers, d’un petit nombre de cellules, parfois

enrobés dans une gelée homogène. On trouve dans ce genre ainsi défini, entre

autre le célèbre «Anacystis nidulans» dont les cultures ont fait l’objet de nom¬

breux travaux de physiologie et de biochimie.

Enfin le nov. gen. Cyanothece, avec comme espèce type C. aeruginosa (= Sy¬

nechococcus aeruginosus Nâg.) réunit 10 espèces.

Cette étude est une monographie très complète et pour chaque espèce sont

données une diagnose, une répartition géographique et une série de figures.

8 tableaux précisent les caractères des espèces, suivant les différents auteurs.

L’illustration, abondante et soignée, groupe 130 figures où sont toujours repro¬

duites les figures originales des premiers descripteurs.

Nous ferons un petit reproche à ce travail : l’absence de clefs de détermina¬

tion, clefs qui auraient facilité la tâche du systématicien. Un travail remarquable

qui met enfin un peu d’ordre dans un groupe très difficile où les caractères

systématiques sont rares.

SKUJA, H. — Zur Kenntnis der Algen Neuseelândischer Torfmoore. Nov. Act.

Reg. Soc. Sc. Upsal. Ser. V : C, 1976, vol. 2 : 1-159.

Il s’agit d’un mémoire posthume du grand algologue décédé en 1972 et dont

K. THOMASSON a publié la biographie dans la Rev. Algol, vol. 11, 2. L’auteur

étudie les algues microscopiques de quelques tourbières acides de Nouvelle Zé¬

lande : 11 récoltes de l’île du Nord et 8 récoltes de l’île méridionale. Il s’agit

d’un travail systématique portant sur un ensemble de 389 espèces et 64 variétés.

Les Zygophycées (ou Conjuguées) occupent la première place avec 237 taxons,

puis viennent les Diatomées : 104 unités systématiques. Les autres groupes

d’algues sont plus faiblement représentés : 32 Cyanophycées, 9 Euglénophycées,

7 Chrysophycées, 4 Xanthophycées. Comme dans toutes les tourbières acides,

les Chlorococcales, avec 27 espèces, sont peu abondantes.

L’île du Sud avec 445 taxons dépasse largement l’île du Nord : 290 taxons.

BIBLIOGRAPHIE

365

Parmi les Desmidiées, algues préférentielles des eaux acides, le genre Cosmarium

(88 taxons) est dominant; il est suivi par Euastrum (30) et Closterium (30)

puis par Staurastrum (25). Dans les Diatomées, la première place revient à

Pinnularia (24 taxons), puis viennent Eunotia (15), Cymbella (11) et Navicula

(H)-

A côté de nombreuses algues acidophiles des régions tempérées, on rencontre

un élément tropical important surtout parmi les Desmidiées et les Diatomées.

Comme il était facile de le prévoir, les nouveautés systématiques sont nom¬

breuses : nous avons dénombré 16 sp. nov., 21 var. nov. et 2 nov. comb. Ces

taxons nouveaux se rencontrent dans les genres Anabaena, Hormidium, Zygo-

gonium, Zygnemopsis, Zygnema, Closterium, Pleurotaenium, Cosmarium (4 nov.

sp. et 7 var. nov.), Arthrodesmus, Xanthidium, Euastrum, Micrasterias, Stauras¬

trum, Spondylosium, Desmidium et Lagynion. Comme on le voit, là aussi les

Conjuguées tiennent la première place.

L’auteur est peu favorable aux innovations systématiques : ainsi il conserve

le nom d'Hormidium (en citant cependant Chlorhormidium) ; il n’accepte pas le

genre Staurodesmus proposé si heureusement par TEILING, et conserve à Ar¬

throdesmus ses limites anciennes. Il utilise encore Gymnozyga au lieu de Bambu-

sina et Ankistrodesmus pour Monoraphidium...

Cette analyse systématique est accompagnée pour de très nombreux taxons,

de remarques et de commentaires très importants. Ainsi il consacre une longue

discussion au genre Zygogonium et montre clairement que le genre Pleurodiscus

n’est qu’un synonyme du précédent.

Comme pour tous les travaux de SKUJA il faut signaler la beauté, la précision

:t l’abondance des illustrations. Le volume se termine par une série de 16 plan¬

tes vraiment merveilleuses qui groupent près de 300 figures.

Ce mémoire est précédé d’une courte préface biographique écrite par T.

■VILLEN et ornée d’une photographie de SKUJA. Comme tous les ouvrages de

e grand algologue, ce mémoire prendra place parmi les classiques de l’algologie

i’eau douce.

SOUTH, G. R. et CARDINAL, A. - Contributions to the flora of marine algae

of Eastern Canada. 1. Introduction, historical review and key to the généra.

Natural. Canad. 100 : 605-630.

Après un rapide historique de l’algologie marine des côtes de l’Est canadien,

es auteurs, dont l’un a déjà dressé un catalogue des algues benthiques de cette

égion, présentent une clef de détermination des genres de Chlorophycées (37

jen.), Phéophycées (61 gen.) et Rhodophycées (70 gen.) recueillies sur les côtes

anadiennes. Une abondante bibliographie complète cette utile mise au point.

366

TABLE DU TOME XI

ABÉLARD, C. et L’HARDY-HALOS, M. T. — A propos de l’ontogenèse des cladomes

surnuméraires et notamment des cladomes épirhizoïdiens chez quelques Delesseria-

cées (Rhodophycées, Céramiales). 72

AHMAD, M. R. - The effect of gibberellic Acid, Kinetin and Indole-3-Acetic acid on

the growth of blue-green Algae in culture.154

ARCHIBALD, R. E. M. — Obituary : Dr B. J. Cholnoky (1899-1972). 8

BOURRELLY, P. - Einar TEILING (1888-1974). 205

COMPERE, P. - Bourrellyodesmus, nouveau genre de Desmidiacées.339

COÛTÉ, A. — Etude comparative du cycle de Liagora tetrasporifera Bôrg. et du Liagora

distenta (Mert.) C. Ag. en culture.273

CULLINANE, J. P. — Vaucheria on «Coral» ( Lithothamnion) Sand.249

FJERDINGSTAD, E., Bo HOLMA and FJERD1NGSTAD, E. J. - The structure of

Oscillatoria limosa Ag. (Cyanophycea) and the formation of hormogonia and ne-

cridia ).261

GASSE, F. - Ultrastructure de quelques Diatomées centriques fossiles d’Ethiopie

révélée par le microscope électronique à balayage.137

GERSON,U. — The associations of Algae with Arthropods (Ire partie). 18

GERSON, U.-The associations of Algae with Arthropods (2nd part, Addendum) . . . 213

JOHN, D. M. - The marine algae of Ivory Coast and Cape Palmas in Liberia (Gulf

of Guinea. 3Q3

KHAN, M. and MATHUR, A. - Algal flora of the rice-fïelds around Dehradun, India. . 333

KAMAT, N. D. — Life history of Dichotomosiphon tuberosus (A. Br.) Ernst.132

LE CALVEZ, Y. - Georges DEFLANDRE (1897-1973). 209

LEMOINE, M. — Contribution a l’étude du genre Lithoporella (Corallinacées). 42

PARKES, H. M. - The presence of tetrasporangia and carposporophytes on the same

thallus in Pterosiphonia thuyoides .299

RICARD, M. - Etude taxinomique des diatomées marines du lagon de Vairao (Tahiti). 161

RICARD, M. - Premier inventaire des diatomées marines du lagon de Tiahura (île de

Moorea, Polynésie Française). 343

SCHWABE, G. H. — Karl Behre (1901-1972) in memoriam. 15

TAYLOR, Wm. R. - Notes on algae from the Tropical Atlantic océan-VIII. 58

THOMASSON, K. — Prof. Henrichs SKUJA (1892-1972). 3

TSUDA, R. T. — Some marine benthic algae from Pitcairn island.325

YACUBSON, S. - El fïtoplancton de la laguna de San Javier del Valle (Esta Mérida)

Venezuela. q.

Source : MNHN, Paris

367

Table des noms d’Auteurs dont les Travaux sont analysés

dans la Bibliographie

Algological studies, 178

ARCHIBALD, R. E. M., 178

BATKO, A., 179

BODARD, M., 179

BOLD.H.C., 361

BOUK, C. B., 179

BOURRELLY, P., 180, 357

BLUMJ.L., 180

CABIOCH, J., 181

CARDINAL, 365

CARR, N. G., 182

CASPER, S. J., 357

COHEN-BAZIRE, G., 183, 198

CORILLION, R., 357, 358

CRAWFORD, R. M., 186

CROASDALE, H. T., 196

DESCY.J.P., 183

DESIKACHARY, J. V., 184

DODGE, J. D., 184, 185, 186

DRAGANO, S.J., 186

DROUET, F., 359

EDWARDS, M. R., 189

FAY, P., 187

FERRARIO, M. E., 186

FEUILLADE, M., 187

FOGG, G. E., 187

FORSTER, K., 188

FOTT.B., 188

GANTT, E., 189

GASSE, F., 189

GAYRAL, P., 360

GREEN, J. C., 194, 195

GUARRERA, S. A., 189

GUERLESQUIN, M., 358

HEYWOOD, P., 189

HIBBERD, D. J., 190

HORTOBAGYI, T., 191

KADLUBOWSKA, J. Z., 192

KALBE.L., 360

KANN.E., 192, 193, 194

KOMAREK, J., 193, 194, 361, 364

KUNISAWA, R., 198

LEADBEATER, B. S. G., 194

LEE, K.W., 361

LEEDALE, G. F., 190

LOPEZ, F. P., 189

LUDVIK, J., 194

MALACALZA, C., 189

MANDEL, M., 198

MANTON, I., 195

MARGALEF, R., 361

MOLLENHAUER, D., 362

Norvegian Journal of Botany, 195

Nova Scotia Research..., 362

PARKE, M., 195

PRESCOTT, G. W., 196

PROVASOLI, L., 189

REINECKE, P., 196

RINOJ. A., 196

ROOS, R., 197

SCHOEMAN, F. R., 197

SEAGRIFF, S. C., 197

SIMS, P. A., 197

SKUJA, H., 364

SOUTH, G. R., 365

STANIER, R. Y., 198

STARMARCH, K., 198, 362

STARR, R. C., 199

STEINJ.R., 199, 200

STEWARD, W. D. P., 187

Surtsey Island, 200, 201

SWALE, E. M. F., 201

TAKAHASHI, E., 201

THRONDSEN, J., 201

TROUGHTON, S. C., 197

TSCHERMAK-WOESS, E., 202

TUPA, D. D., 362

VINYARD, W. C., 196

WALSBY, A.E., 187, 202

WHITTON, B. A., 182

WUTRICH, M., 363

YACUBSON, S., 171,363

Source : MNHN, Paris