2. SIMULIIDAE

By E. G. GisBins

(With Plate xx1)

DurRING December 1934 while accompanying the British Museum East

African Expedition the writer was able to devote a few days to the breeding of

Simuliidae in the Namwamba Valley of Mount Ruwenzori. At the time of our

visit the rains were subsiding, the level of the Namwamba was beginning to fall,

and Simuliid larvae and pupae were plentiful on the surfaces of the huge boul-

ders which cause an impediment in the river’s course. The small collection made

included five species, two of which proved new to science.! In order to make the

study of the Simuliudae of the mountain more complete, details are included of

Simulium taylort Gibbins which was taken by the writer from the Bwamba

Pass in 1931. Adults of three additional species were captured by Dr. F. W.

Edwards: Simuliwmn duodecmum Gibbins was represented by a single male

which was caught on the west side of Ruwenzori in the Bwamba Pass, S. dam-

nosum Theobald by a single female taken in the vicinity of the River Mobuku

at 4000 ft. and S. cervicornutum Pomeroy by six females which were taken on

the window inside a bungalow at Kilembe (4500 ft.) where they made no attempt

to bite. Simulium dentulosum and S. kauntzeum have been previously recorded

from the Butahu Valley on the west side of the mountain (1936).

Simulium dentulosum and S. kauntzeum were found breeding at an altitude

of 10,200 ft. in the Namwamba Valley of Mount Ruwenzori and Simuuliwm

larvae (species undetermined) were found by Mr. D. R. Buxton at 12,000 ft. in

the Nyamgasani Wena e Hitherto it was not known that Simulidae bred at

such a high altitude. S. dentulosum and S. masabae were both breeding at

an elevation of 9500 ‘ on the slopes of Mt. Elgon, but though a thorough

search was made in apparently identical watercourses at higher altitudes the

early stages were not found.

Of particular interest was the discovery of three different forms of the pupal

respiratory organ in S. dentulosum. While the adult differed only in size

and was morphologically identical with the type in both sexes, the respiratory

organ of the pupa conformed to three distinct forms with no apparent variation ;

' These two species (S. kauntzeum Gibbins and S, bisnovem Gibbins) were at first de

scribed as new in the present report, but owing to delays in publication and to the fact

that the author wished to refer to them in a pape ah dh preliminary diagnoses were

published by him in 1938 (Ann. Trop. Med., 32.)—F.

J; 2

12 RUWENZORI EXPEDITION

these forms occurred separately at three localities at different altitudes in the

course of the River Namwamba.

With the exception of Simulium bisnovem, of which larva is unknown, and

S. dentulosum, early stages of which have already been described in an earlier

communication, the present study includes an account of the larva and pupa of

each species. The adults of both sexes of the new species are dealt with,

while the male and female terminalia of S. debegene and lepidum and the male

terminalia of S. dentulosum are redescribed and figured in greater detail. Notes

on the breeding places are also given.

Fig. 1.—Female terminalia: S. bisnovem ventral view (a),

paraproct and cercus, lateral view (b). S. kauntzeum

paraproct and cercus, lateral view (c), ventral view (d).

Simulium kauntzeum Gibbins

FEMALE: Length 4mm.; wing 4:5 mm.

Head. Vertex and fronto-clypeus slate grey; vertex covered with silver

and rather wide. Antenna black.

Thorax: Mesonotum dull black, uniformly covered with short golden scales

and with long outstanding black hairs along the posterior margin. Plewrae

slate-blue with a dense patch of pale golden scales on the membrane behind the

thoracic spiracle. Halteres dark brown.

Abdomen lustrous dark brown, thinly and uniformly covered with short

pale golden scales; these are interspersed with long outstanding black hairs on

the seventh and eighth segments; first tergite brown with dense lateral fringe

of pale yellow hairs, a few are of moderate length but the majority are short.

Spermatheca oval and heavily chitinized; outer wall unsculptured. Terminalia:

SIMULIIDAE 113}

Eighth sternite and anterior gonopophyses as in S. bisnovem but with the latter

more densely covered with setae; paraproct and cerci as in Fig. 1, ¢ and d.

Legs dark brown, coxae with long pale yellow scales, front femora sprinkled

with yellow scales, front and hind tibiae with the basal two-thirds pale.

Calcipala present and pedisulcus distinct. Claws with a well-developed basal

projection,

Wings with spines interspersed with hairs on the costa, hairs on the basal

two-thirds of the subcosta and base of the radius, the radial sector.

the cubitus with a distinct double bend; basal cell present.

Mate. Length 4 mm.; wing 4-5 mm. :

Head. Clypeus black with numerous long black outstanding hairs. Eyes

closely approximated. Antenna as in female.

Tig. 2.—Simulium kauntzeum, Male terminalia: coxite and

clasper (a); phallosome, anterior part, ventral view (0),

lateral view (c), cercus (d).

Thorax. Mesonotum velvet-black covered with golden scales. Scutellum

brown with narrow deep golden scales and long outstanding black hairs on the

posterior margin. Plewrae brown with patch of very long narrow scales on the

membrane behind the thoracic spiracle. Halterves dark brown.

Abdomen velvet-black, very sparsely covered with short deep golden scales;

first tergite with dense lateral fringe of long pale hairs which are dark brown

basally. Terminalia (Fig. 2). Coxite large, about half as long again as the

clasper; in ventral view it is convex outwardly with its inner side divided almost

equally into a lower vertical and an upper slightly convex edge. The clasper,

which bears a short tooth on its lower apical edge shows no reduction in width

! The terminology of the male terminalia used throughout this report is that described

in a former paper (1935).

14 RUWENZORI EXPEDITION

basally. Phallosome, anterior part (Fig. 2, 6 and c), broad in ventral view with a

peculiarly long anterior projection bearing short setae; median process broad,

short and bifid distally; posterior part as in dentulosum. Cercus (Fig. 2, d)

circular with short stout bristles.

Legs dark brown. Front legs: femora sprinkled with silver scales and with

very long dark brown hairs along the posterior edge; basal two-thirds of tibiae

covered with silver scales. Middle legs: basal half of tibiae covered with

yellow scales. Hind legs: basal third of tibiae with silver scales; first tarsal

segment very broad; calcipala rounded and pedisulcus distinct.

Wings as in female but with a few hairs only on the base of the subcosta.

Fig. 3.—Larva. Terminal teeth of mentum of S. kawntzeum (a), S. lepidum (b) and

S. taylovi (c). Part of front to show pigmentation: S. kauntzeum (d), S. debegene (e)

Palp of S. debegene (f). Mandible: S. debegene (g), S. kauntzeum (h).

Larva. Length of mature larva 13 mm. General colour dark grey.

Head. Front with pigmented areas as in Fig. 3,d. Antenna normal, slightly

longer than the base of the feeding brushes. Palp as in S. debegene but not so

heavily chitinized. Mandible (Fig. 3, h) with 3 heavily chitinized teeth,

one of which, the outer, is slightly longer than the rest and with ro smaller

lightly chitinized teeth which protrude from its concave surface; of the usual

paired lateral teeth the upper is considerably larger than the lower which is

small and inconspicuous. Mentwm with a terminal row of the usual 9 heavily

chitinized teeth asin Fig. 3, a, the median, which is large and prominent is about

twice the length of the outer; on either side lie about 34 strong spines arranged

irregularly two and three deep along the inner side of a heavily chitinized margin.

Feeding brushes with about 50 bristles, some 14 of which are short.

Thorax. Pseudopod broad and long.

SIMULIIDAE I5

Abdomen with minute spines. Anal gills trilobed, the central lobe with 14

and the lateral with 12 finger-like processes. Anal armature normal. Circlet

with about 300 rows of 30 to 35 strong hooks.

Pura. Head and thorax with disc-like tubercles and short, slender, simple

trichomes. Respiratory organ (Fig. 4, a) semi-translucent, composed of g long

stout filaments with deeply-pigmented tips, 8 of which are arranged in

pairs, and arise from short stems, and one stumpy spine-like basal process.

Under high magnification the outer wall shows the fine striated appearance

depicted in the figure and is slightly more pigmented than in the case of

S. bisnovem,

Fig. 4.—Respiratory organ: S. kauntzeum (a), S. bisnovem (b), S. debegene (c).

Abdomen. Terminal segment without hooks or spines. Dorso-lateral

surface: second segment with a pair of minute spines; third and fourth seg-

ments with four equally spaced hooks. Ventro-lateral surface: fourth segment

with three minute spines, the inner of which is bifid: fifth, sixth and seventh

segments with a pair of strong hooks, those on the two latter segments are

widely spaced.

The cocoon is a gelatinous structure 6 mm. in length with a lateral projection

as depicted in Fig. 5, a.

RuWENzor1: Namwamba Valley, Holotype 3, bred from isolated pupa,

Kiriruma (10,200 ft.), 25.xii.34 (Gibbins). Allotype 9, and 8 g, same data,

also 4 ¢, 1 9 captured, same locality (Edwards).

16 RUWENZORI EXPEDITION

Simulium kauntzeum was found breeding in association with the large form

of S. dentulosum on the surface of clean dark stones which were lying below

cascades in the River Namwamba near Kiriruma at an altitude of 10,200 ft.; the

river in this situation was swiftly flowing and partly shaded by tall tree heath.

WOV

DUOv

S. debegene lateral view (c),

Fig. 5.—Cocoon. S. kauntzeum (a), S. bisnovem (

; S. taylori, ventral

ventral view (d); S. lepidum veal view (e), es view (f)

view (g), lateral view (h).

Simulium bisnovem Gibbins

FEMALE. Length 4:5 mm.; wing 5 mm.

Head. Vertex and fronto-clypeus slate-grey, covered with yellow scales

which are interspersed with long black hairs. Antenna dark brown; scape, first

and base of second flagellar segment light brown.

Thorax. Mesonotum coppery-brown, sparsely covered with short golden

scales and broadly edged slate-blue with dense long narrow golden scales, bear-

ing three long narrow dark blue longitudinal stripes of equal length; the outer

stripes converging slightly on the median anteriorly. Scutellum coppery-brown

with narrow golden scales interspersed with long black hairs and with a row of

SIMULIIDAE 17

long outstanding golden scales situated on either side on the posterior margin.

Pleurae slate-blue without a patch of soft hairs on the membrane behind the

thoracic spiracle. Halteres dark brown.

Abdomen lustrous dark brown. First and second segments densely covered

with golden scales which are sparse on the remaining segments; first tergite

brown with lateral fringe of yellow hairs of moderate length. Tevminalia

(lig. r, a). Eighth sternite with a median chitinized area; anterior gonopo-

physes thinly covered with fine setae and tapering slightly distally; paraprocts

broad in ventral view and almost equally divided into a spiculate basal area and

a heavily chitinized distal area; in lateral aspect (Fig. 1, 6) its large size and

heavily chitinized rounded anterior projection and spiculate basal area are

clearly seen. The cercus is small.

Legs dark brown, femora sprinkled with golden scales; basal two-thirds of

tibiae of front legs with silver scales and middle legs with yellow scales; hind

legs with basal two-thirds of tibiae yellow and basal half of first tarsal segment

with silver scales. Claws with a basal tooth.

Wings as in S. kauntzewm but lacking the basal cell.

Mate. Length 4 mm.; wing 4 mm.

Head. Front-clypeus slate-grey with long black hairs. Antenna dark

brown with long dark hairs on the scape and first flagellar segment. Eyes

closely approximated with a row of dark hairs between them.

Thorax. Mesonotum velvet-black, densely covered with long narrow golden

scales; these are sparse in the median area and interspersed with long black

hairs posteriorly. Scztellwm with golden scales and long black marginal hairs.

Pleurae and halteres as in female.

Abdomen velvet-black. Second, third and fourth segments with dense

golden scales; fifth, sixth and seventh segments with sparse golden scales and a

slate-blue iridescent lateral patch; first tergite dark brown with dense lateral

fringe of long pale yellow hairs. Yerminalia (Fig. 6). Coxtte about the same

length as the clasper and of similar shape to S. kawntzeum. Clasper tapering

gradually to a pointed tip with a small chitinized terminal tooth. Phallosome

anterior part (Fig. 6, b): small and heart-shaped with a long forward projection

bearing setae and with long narrow basal processes which converge in the median

area; median process large, broadening distally with a peculiar posterior flap

on either side, posterior part (Fig. 6, c) membranous with strong spines and a

long narrow apodeme. Cercus as in Fig. 6, d.

Legs as in female except for the presence of long dark brown hairs on the

front femora, golden scales on the mid femora and silver scales on the first hind

tarsal segment which is wide and rounded apically.

Wing as in female but with a basal cell.

LARVA. Unknown.

Pura. Head and thorax with sparse disc-like tubercles and simple trichomes.

18 RUWENZORI EXPEDITION

Respiratory organ (Fig. 4, b) pale and semi-translucent, comprising 18 stout

filaments arranged in pairs with deeply pigmented tips and a finely striated

outer wall.

Abdomen. Terminal segments with a pair of inwardly curved hooks. Dorso-

lateral surface: first and second segments with four closely placed short spicules;

third and fourth segments with four closely placed strong hooks. Ventro-

lateral surface: sixth, seventh and eighth segments with a pair of strong hooks;

those on the seventh and eighth segments widely spaced.

Fig. 6.—Male terminalia. Simulium bisnovem, coxite and clasper (a); phallosome,

lateral view (c), anterior part, ventral view (b), cercus (d).

The cocoon is a gelatinous pocket 5 mm. in length as illustrated in Fig. 5, 0.

RuUWENzORI: Namwamba Valley, 6500 ft., type ¢ and allotype ° bred from

isolated pupae (Gibbins), also 2 g¢ I Q caught (Edwards); Bwamba Pass,

17.X1.193I, I g bred from pupa (Gzbbins).

A few pupae of Simulium bisnovem were found attached to slender tree roots

dangling in a cascade in the river near Kyanjoke (6500 ft.)._ The writer collected

a, single pupa of this species from the River Mpanga at about 6000 ft. on the

Ruwenzori foothills in the Bwamba Pass in 1931. In this case the pupa came

from a small stone lying beneath a cascade and was associated with numerous

pupae of S. dentulosum. This specimen, from which a male was bred, was

previously referred to as N2 (1934).

Simulium dentulosum Roubaud

In the River Namwamba three distinct forms of. Simulium dentulosum were

found breeding ; these are easily separable on the character of the respiratory

SIMULIIDAE 19

organ of the pupa, but apart from a difference in size the adults of both sexes were

identical with those from the type locality. At Kiriruma, (10,200 ft.), the highest

altitude at which Simulium were taken by the writer, pupae of a large form were

occurring in association with those of S. kauntzeum. This form measured 4-6 mm.

with a wing of 4-5 mm. as against 3-5 mm. and 3:7 mm. respectively in specimens

from the type locality. No distinction was noted in the terminalia of the adult

and the pupae differed only in size and in the size and comparative length of the

\ (BZ

EEE!

fmm,

Pig. 7.—Simulium dentulosum. Respiratory organ of pupa. WKilembe form (a), Kiriruma

form (6), IXtyanjoke form (c). (Drawn to the same scale.) It should be noted that owing to

the fact that the pupae of the forms (b) and (c) are very much larger than those of (a)

difference in relative size of the respiratory organs is not so great as appears in the drawings.

individual filaments of the respiratory organ. Lower down the river, at Kyan-

joke (6500 ft.), associated with the early stages of S. bisnovem, pupae were ob-

tained of a form from which the bred adult was slightly larger than that of the

type. Though exhibiting no distinguishing characters externally or in the male

terminalia the pupal respiratory organ was conspicuously different and larger

than in any of the other forms. Still lower in the river’s course, at Kilembe

(4500 ft.), the smaller form was found which had a respiratory organ similar to

that of pupae from the type locality from which typical adults of S. dentulosum

have been bred. The three forms of the respiratory organ of the pupa, drawn

to the same scale, are illustrated in Fig. 7. It will be seen that the filaments

20 RUWENZORI EXPEDITION

number 14 and are paired in all cases. While they arise similarly in the Kilembe

(Fig. 7, a) and the Kiriruma (Fig. 7, 6) forms in the latter the two lateral pairs

on one side are considerably longer than the rest, whereas in the Kilembe

(type) form all the filaments are of uniform length. In the Kyanjoke form

(Fig. 7,c), in which this organ is the largest of the three, the filaments are much

stouter and the base is broad and bladder-like with a short lateral arm support-

ing two pairs of filaments. The general arrangement and sculpture of the outer

Hig. 8.—Male terminalia: Simulium dentulosum, phallosome, lateral view (a), anterior part,

ventral view (b), cercus (c) ; S. debegene, coxite and clasper (d), phallosome, anterior part,

ventral view (e), lateral view (f), cercus (g).

wall of the filaments is similar in every case though in the Kyanjoke form the

pigmented nodules are more widely spaced.

The terminalia (Fig.8,a—c) of an isolated specimen from the type locality have

been dissected and the parts are shown in order to facilitate the accurate deter-

mination of the species.

Simulium debegene De Meillon

Dr. De Meillon’s description (1934) of the male and female is supplemented

by the following notes on the terminalia.

FEMALE. The terminalia shown in ventral and lateral aspect in Fig. 9,

a and b, have been clearly described. The characteristic paraproct is more

highly developed than in any other known African species.

SIMULIIDAE 21

MALE. Fig. 8, d—g, shows the terminalia which were dissected out from a

mature pupa. The coxite is small, about half as long as the clasper which is

slender and tapers gradually to a rounded end bearing a small tooth on its lower

extremity. Phallosome, anterior part (Fig. 8, e and /) rounded anteriorly with

rows of downward projecting spines covering its ventral surface and with large

basal processes; median process bifid, expanded distally with a posterior flap

on either side ; posterior part similar to S. bisnovem but with fewer and shorter

Fig. 9.—Female terminalia. Simuliwm debegene, ventral view (a), lateral view (6).

S. lepidum, eighth sternite and right anterior gonapophyse (c), paraproct and

cercus, lateral and ventral views (e); S. taylori, paraproct and cercus, lateral and

ventral views (d).

spines and without spines on the lower surface of the membrane; apodeme

somewhat shorter. Cercus as in Fig. 8, g.

LARVA. Length of mature larva 9 mm. General colour dark grey.

Head. Front heavily chitinized and sparsely spiculate with irregular pale

patches asin Fig. 3, e. Palp (Fig. 3, f) with a very heavily chitinized broad band,

covered with short spines bearing numerous long slender bristles on its un-

chitinized base. Antenna normal about as long as the base of the feeding brushes.

Mentum with the usual terminal row of nine heavily chitinized teeth (which

were somewhat broken in the only specimen of this species taken) with a single

oblique row of eight to nine stout spines on either side. Mandible (Fig. 3, 2)

with a main and three smaller heavily chitinized teeth situated above and with

22 RUWENZORI EXPEDITION

ten secondary teeth; the usual paired lower teeth are small and inconspicuous.

Feeding brushes with about 57 long and 12 short bristles.

Thorax. Pseudopod broad and long.

Abdomen. Normal. Anal gills trilobed, each lobe with ro to 12 finger-like

processes. Circlet with about 320 rows of 60 to 70 strong hooks.

Pupa. Head and thorax with disc-like tubercles and short simple trichomes.

Respiratory organ (Fig. 4, c) pale and semi-translucent, composed of four long

uniform filaments, three of which arise posteriorly; they have a finely reticulated

outer wall with rounded ends.

Fig. ro.—Male terminaha. Simulium lepidum, coxite and clasper (a); phallosome,

lateral view (b), anterior part, ventral view (c), cercus (d).

Abdomen without terminal hooks or spines. Dorso-lateral surface: second

segment with five minute spines, third and fourth with four equally spaced

strong hooks, sixth, seventh, and eighth with a small spiculate patch. Ventro-

lateral surface: fourth segment with two short heavily chitinized spines, sixth

and seventh with a pair of strong hooks; those on the latter segment widely

spaced, eighth with a simple lateral hook.

The cocoon (Fig. 5, c and d) is a sheath-like gelatinous structure 5-5 mm. in

length.

RuweEnzor1: Namwamba Valley, Kyanjoke (6500 ft). Two pupae and one

larva were taken from stones removed from cascades in the river which was

heavily shaded by dense forest on either side; one adult female was reared.

SIMULIIDAE 23

Originally described from specimens obtained at Magoebaskloof, Tzaneen,

in the Transvaal at 3—4000 ft.

Simulium lepidum De Meillon

The male and female were described by De Meillon (1935). Below the ter-

minalia of both sexes are redescribed and figured in greater detail. The larva

is described for the first time and a full description of the pupa is also given.

FEMALE.

Terminalia (Fig. 9, c and e). Eight sternite with a lightly chitinized

median area; anterior gonopophyses long and tapering almost to a point;

paraproct in ventral view with a large rounded median process on its inner

side and a small anterior projection armed with a pair of spines. Cercus small.

MALE.

Terminalia (Fig. 10). Coxite (Fig. 10, a) about twice the length of the

clasper, slightly narrower apically than basally with a short inner anterior

projection. Clasper tapering gradually to the tip which bears a single broad

chitinized tooth. Phallosome (Fig. to, 6) anterior part (Fig. 10, c) simulating an

inverted V in ventral view with a chitinized V shaped anterior end serrated

outwardly with a basal tuft of long hairs; in lateral view it is broad, serrated

anteriorly and armed with a strong tooth-like process on its posterior surface,

the downward projecting processes are broad and rounded basally; median

process long and narrow; posterior part membranous and bearing large back-

wardly projecting spine-like processes. Cercus (Fig. 10, @) small and with about

seven long apical bristles arising from boss-like bases.

Larva. Length of mature larva g mm. General colour grey.

Head. Front lacking pigmented areas. Antenna normal, slightly longer

than the base of the feeding brushes. Mandible with three main heavily chiti-

nized teeth, the median of which is shorter than the rest and with seven smaller

lightly chitinized teeth which protrude from its concave surface; of the usual

paired lateral teeth the upper is slender, pointed and considerably longer than

the lower which is small and inconspicuous. Mentwm with a terminal row of

nine heavily chitinized teeth (Fig. 3, 6); with the exception of the median which

is considerably the longest all are of uniform length, the outer bearing a shoulder

on its inner edge; on either side is a single oblique row of 6 to 7 strong spines

and in the sub-median basal area lies a single spine which is equal in length to

the smallest. Feeding brushes with 40 to 50 long bristles.

Thorax. Pseudopod short and broad reaching just above the head suture.

Abdomen. Terminal segments with scattered minute spines on the dorsal

surface. Anal gills trilobed; in addition to one large process the median lobe

has six and the outer five small finger-like processes. Anal armature normal,

Circlet with about 220 rows of about 35 to 4o strong hooks

24 RUWENZORI EXPEDITION

Pupa. Head and thorax with numerous large disc-like tubercles; trichomes

simple with the exception of two pairs situated near the ventral suture; these

are long and slender with two branches and arise from a short stem. Respiratory

organ (Fig. 11, 6). Arising medially from a broad base are three upright stems

each bearing a single lateral branch and eight slender filaments which arise

singly from the ventral surface. The latter are fragile and semi-translucent,

whereas the single-branched main stems, which have near the base an outer

wall covered with small nodules as depicted in the figure, are strong and pig-

mented. Two of the main stems unite a short distance above the third and on

either side at the base lying horizontal and in contact with the pupa is a single

semi-translucent caudal appendage.

O-Smm

Fig. 11.—Respiratory organ of pupa. S. taylovi (a), S. lepidum (b).

Abdomen. Dorso-lateral surface: third and fourth segments with four

equally spaced strong hooks. Ventro-lateral surface: sixth, seventh and eighth

segments with a pair of hooks; these are widely spaced on the last two.

Cocoon (Fig. 5, e and f) 4 mm. in length, dark brown and gelatinous.

RUWENZzORI: Namwamba Valley, near Kilembe (4500 ft.), Pupae on loose

stones (Edwards).

Larvae and pupae from which many adults were reared were also found in

abundance by the writer on the face of vertical rock and on the blades of

elephant grass dipping in the swiftly flowing River Nabigwo on Mt. Nkokonjeru

(Eastern Uganda) at an altitude of about 6000 ft.

SIMULIIDAE

Simulium taylori Gibbins

FEMALE. Length 3 mm.; wing 3:5 mm.

Head. Vertex and fronto-clypeus slate-grey, covered with dark hairs.

Antenna dark brown. Palp: sensory spot small and circular.

Thorax. Mesonotum dull black, densely covered with brassy scales which

are interspersed with outstanding long black hairs posteriorly. Pleuwrae slate

blue, lacking hairs on the membrane behind the thoracic spiracle. Halteres

light brown.

Abdomen dull black, covered with golden scales laterally; first tergite dark

brown with dense lateral fringe of pale hairs; dorsal surface with deep reddish

Fig. 12.—Male terminalia. Simulium taylori, coxite and clasper (a), phallosome,

anterior part: ventral view (b) lateral view (c); cercus (d). (Posterior part of

phallosome as in S. lepidwm.)

brown scales with the exception of the first and second segments which are

densely covered with long narrow golden scales. Terminalia. Eighth sternite

as in lepidwm. Paraproct (Fig. 9, d) differing noticeably from that of lepidwm

in the character of its inner side which lacks the median bulge when seen in

ventral aspect.

Legs brown, basal half of femora of front legs with golden scales; basal

two-thirds of front and mid tibiae and basal half of hind tibiae and first tarsal

segment with silver scales. Calcipala present and pedisulcus distinct. Claws

simple.

Wings with a basal cell, hairs along the sub-costa and on the base of the

radius.

MALE. Length 2-5 mm.; wing 3 mm.

Head. Clypeus slate-grey, covered with outstanding long black hairs.

Antenna dark brown,

Thorax. Mesonotwm velvet-black, densely covered with long narrow golden

26 RUWENZORI EXPEDITION

scales. Scutellum velvet-black with sparse golden scales and dense outstanding

long black hairs. Pleuvae as in female. Halteres dark brown.

Abdomen velvet-black, thinly covered with narrow dark brown scales and

with a lateral, broad, diagonal slate-blue patch extending from the apical edge

of the fifth to the seventh segment; first tergite dark brown with dense long

dark brown hairs. Terminalia (Fig. 12). Coxite (Fig. 12, a) about twice the

length of the clasper and in ventral view showing a constriction in the anterior

third with a long inner apical projection. Clasper tapering from the distal

two-thirds to a rounded tip with a sub-apical chitinized tooth. Phallosome,

anterior part (Fig. 12, b and c) similar in shape to S. lebidum but smaller apically

and lacking the tuft of long hairs; median process short and broad; posterior

part asin lepidum. Cercus (Fig. 12, d) indistinct with setae round its outer edge,

Legs dark brown, tibiae with basal two-thirds of front legs and basal third

of middle legs with silver scales; hind tibiae with a small basal patch of yellow

scales.

Wings with basal cell and hairs on the base of the radius; sub-costa lacking

hairs.

Larva. Length of mature larva 7 mm. General colour grey.

Head. Front without pigmented areas. Antenna normal, slightly longer

than the base of the feeding brushes. Mandible as in lepidum. Mentum as in

lepidum with the exception of the terminal row of heavily chitinized teeth which

are of similar length (Fig. 3, c). Peeding brushes as in lepidum.

Thorax. Pseudopod as in lepidum.

Abdomen without scales or spines. Anal gills trilobed, long and simple,

Anal armature normal. Anal circlet as in lepidum.

Pupa. Head and thorax with disc-like tubercles and simple trichomes.

Respiratory organ (Fig. 11, a). From a main slightly chitinized broad basal

appendage arise 15 slender semi-translucent filaments; these arise singly with

the exception of seven, which originate from two short stems covered with small

nodules as depicted in the figure. The two stems arise on the dorsal surface

and support a pair and five filaments respectively, one of the latter group being

considerably shorter than the rest. Unlike that of Jeprdum the basal appendage

is not identical on either side: one side, the longer, tapers to the tip while the

other is rounded and bears a short sub-apical semi-translucent filament on its

upper surface.

Abdomen as in lepidum.

Cocoon (Fig. 5, g and /), 2-5 mm. in length, dark brown and gelatinous.

RUWENZORI: Bwamba Pass, 17.xi.193I, type 3, allotype 9, and 5 g 12

paratypes reared from isolated pupae (Gibbins).

Simulium taylort was found breeding in association with S. dentulosum and

S. bisnovem in the Bwamba Pass of Mount Ruwenzori at an altitude of about

7000 ft. Larvae and pupae were present in small numbers on clean stones which

SIMULIIDAE 27

were removed from below cascades in heavily shaded parts of the River Mpanga.

The pupae were easily distinguished from those of the other two species on

account of their small size and less obvious respiratory filaments.

REFERENCES

De Meillon, B., 1934. Studies on Insects of Medical Importance in South

Africa. Pub. S. African Inst. Med. Res., 6: 253.

1935. Studies on Insects of Medical Importance in South

Africa, Part II. Ibid., 6: 3306.

Gibbins, E. G., 1934. Further Studies on Ethiopian Simuliidae. Trans. R.

Ent. Soc. Lond., 82: 63.

1935. On the Male Terminalia of Simuliidae. Ann. Trop. Med.

& Parasit., 29: 317.

1936. Congo Simuliidae. Ann. Trop. Med. & Parasit., 30; 133.

1938. Notes on Ethiopian Simuliidae—II. /bid., 32.

. Plate XXI

_ RUWENZORI

River Namwamba at 10,200 feet.

Habitat of Simulium kauntzeum Gibbins

RUWENZORI EXPEDITION—VOL. I PLATE XXI

3. MOSQUITOES

By F. W. Epwarps and E. G, GIBBINS

(With Plate xxi)

DurinG the British Museum Expedition of 1934-5 special attention was

given to the mosquitoes of the bamboo zone on the Birunga Mountains and

Ruwenzori; not only were the ground-pools in swampy areas of this zone exam-

ined, but the bamboos themselves were subjected to careful search. Several

species were found breeding in the bamboo stems, the larvae being taken in

clear water, a few inches deep, lying above nodes in the stems of growing bamboo

damaged by a boring caterpillar. Large numbers of bamboo stems were

examined and the results showed that those with a narrow hole about 12 by

6mm. were most favoured. A hole of smaller dimensions appeared to be of

insufficient size to allow the female to enter. The procedure adopted was to

saw off a likely looking piece of bamboo, which by its sound on tapping indicated

the presence of water, some distance above and just below the node, taking care

not to split the stem. Its contents were then emptied into a receptacle and the

inside thoroughly washed out two or three times with clean water as invariably

some of the larvae stayed behind.

The most interesting results of this investigation were: (1) the discovery

of three new species of Culicine mosquitoes (A édes angustus, A. bambusae and

A. gibbinsi), diagnoses of which have been published by Edwards* (Bull. Ent.

Res., 26: 134-135, 1935); and (2) the demonstration of the similarity in the

mosquito fauna of the bamboo zone of these two mountain ranges. In some

parts of tropical Africa species of the subgenus Dunnius and other species of

Aédes of the apicoannulatus group are characteristic inhabitants of the bamboos,

but none of these was found in Uganda.

Search was also made for mosquito-larvae in the tree-heath and Seneczo

zones, above the bamboo, but none was found. It would seem that on these

mountains mosquitoes do not occur above about gooo ft. altitude.

More numerous species were obtained in the foothills of Ruwenzori, but

these are of no special interest, all being widely distributed and well-known

forms.

All the species obtained during the 1934-5 expedition in these areas are

enumerated below, and in order to complete the list of mosquitoes known to

occur on Ruwenzori some earlier records are noted, and a note is also included

of further specimens obtained by Mr. J. F. Shillito in 1936.

* Fuller descriptions and figures of these species will appear in Part [11 of ‘' Mosquitoes

of the Ethiopian Region,’’ now in preparation.

I, 3.

30 RUWENZORI EXPEDITION

1. THE BAMBOO ZONE IN KIGEZI

(BIRUNGA AND NEIGHBOURING MOUNTAINS)

Anopheles Meigen

Anopheles garnhamt Edw. A single male reared from a larva found in a

swamp in the saddle between Mts. Mgahinga and Sabinio(LugeziCamp), altitude

about 8000 ft. This was the only species of Anopheles found on the mountains,

and apparently it has a wide distribution at a rather high altitude in East

Africa; specimens were also taken during the course of the expedition on Mt.

Kinangop, Aberdare Mts., at about 8000 ft., and on Mt. Elgon (Kenya side) at

about 11,000 ft.

Uranotaenia Lynch

Uranotaenia shilitonis Edw. Larvae numerous in bamboos, both on Mts.

Mgahinga and Sabinio and on the Kigezi mountains at Kanaba and Muko,

under the circumstances noted in the introduction to this paper. Neither

adults nor larvae differ in any appreciable respects from those from the type

locality (Fort Portal district).

Aédes Meigen

Aédes (Stegomyia) bambusae Edw. Larvae numerous in bamboos in all the

above localities, in company with the Uranotaenia.

Aédes (Stegomyia) angustus Edw. Taken together with the last two species;

it was perhaps commoner than A. bambusae at Muko, whereas the reverse was

the case in the Birungas.

Aédes (Aédimorphus) dentatus Theo. Larvae numerous in a rather open

temporary swamp at Kanaba Gap, and also at Lugezi Camp.

Aédes (Aédimorphus) gibbinsi Edw. Larvae numerous in swamp near

Lugezi Camp in company with An. garnhami and the species of Culex mentioned

below. Adults also taken biting in the bamboo forest here, and also in the

bamboo zone of the Kigezi Mts., near Behungi by E. G. Gibbins in December

1932.

Eretmopodites chrysogaster Graham. At Muko, in a locality where the

bamboo had been cut, the larvae were numerous in the open stumps, and in a

fallen bamboo pole, lying nearly horizontal, which had been split open along

its upper surface and become partly filled with rain-water, the early stages

were associated with those of Aédes (Stegomyia) angustus.

Culex Linnaeus

Culex andersont Edw. Larvae of this species were found at Muko in the

fallen split bamboos just mentioned; they occupied the lower sections of the

MOSQUITOES Gye

bamboo whereas the Aédes and Evetmopodites were in the upper sections.

Larvae were also found (and one male bred) in a small rock pool in the bed of

a temporary stream at 7000 ft. on Mt. Muhavura.

Culex ninagongoensis Edw. Larvae were numerous in the swamp near

Lugezi camp in company with Aédes gibbinsi,

Culex vansomerent Edw., ssp.n. macrophyllus. Many adults of a species of

Culex closely resembling C. vansomereni, though showing a slight difference in

male genitalia from typical specimens from Kenya, were bred from larvae

found in the swamp at Lugezi camp. Unfortunately no isolated larval skins

were preserved, but whole larvae from the same source bore a close resemblance

to C. andersont (a species of which no adults were reared or seen in the locality),

and certainly did not exhibit the marked characteristics of C. vansomerent.

If, as seems almost certain, these larvae belonged to the adults mentioned

above, it is probable that the form must be treated as specifically distinct

from both C. andersont and C. vansomereni. Meanwhile the above subspecific

name is proposed for the adult, the male hypopygium of which differs from

the typical form in the much larger leaf on the lobe of the coxite, and slightly

in the form of the teeth on the mesosome, and in the shape of the style. In

addition ssp. macrophyllus difiers from typical vansomerent (in both sexes) in

having no scales on a small area immediately below the subalar knob of

the pleurae.

Culex pipiens L. This species did not occur in the bamboo zone, but was

found by Ford breeding in great numbers in the fringing swamps of Lake

Mutanda.

2. THE BAMBOO ZONE ON RUWENZORI

Megarhinus Robineau-Desvoidy

Megarhinus sp. Two or three larvae of a Megarhinus were obtained by

our native collector Kabanga in bamboos in the Nyamgasani Valley; unfortun-

ately all of them died after arrival in the laboratory in Kampala, so that specific

determination was impossible. Hancock (1932) records finding a Megarhinus

pupa in a bamboo on the Bwamba pass, and suggests that it may have been

M. aeneus Evans.

Uranotaenia Lynch

Uranotaenia shillitonis Edw. Also found in bamboos in the Nyamgasani

Valley; previously recorded by Hancock from bamboos on the Bwamba Pass.

It is not confined to the bamboo zone, the first specimens having been obtained

by Shillito from reeds at Nyakasura, near Fort Portal.

32 RUWENZORI EXPEDITION

Aédes Meigen

Aédes (Aédimorphus) gibbinsi Edw. At Kararama Camp, Namwamba

Valley, 8000 ft., in ground pools of muddy water.

Culex Linnaeus

Culex nebulosus Theo, This was reported by Hancock as occurring in both

open and bored bamboos on the Bwamba Pass. It was not found in the bamboo

zone during the 1934-5 expedition.

Culex minagongoensis Edw. In ground pools at Kararama Camp, associated

with Aédes gibbins:. Also recorded by Hancock from the Bujuku Valley.

Culex hopkinst Edw. Found in company with the last at Kararama Camp.

Culex andersom Edw. In company with the last.

Culex vansomerent Edw. ssp. n. toroensts. In company with the last. These

specimens have the male hypopygium almost exactly as in the typical form,

and do not show the enlarged leaf and other slight peculiarities seen in specimens

from Kigezi; on the other hand they agree with ssp. macrophyllus in having

no subalar scales. Quite similar specimens were obtained by Shillito in 1936

at Kisomoro, near Fort Portal, one male being reared from an isolated larva

similar to that figured by Hopkins (Mosq. Ethiop. Reg., 1: 211) as Culex sp.

indet.; it would seem therefore that Hopkins’ peculiar Culex larva (recorded

from Mihunga, Mobuku Valley, Ruwenzori, as well as from Mt. Elgon) can

only be a variety or subspecies of C. vansomerent.

Culex moucheti Edw. Breeding in bamboo stump at Izahura, Bwamba

(Shillito, 1936).

3. THE FOOTHILLS OF RUWENZORI

The following list could no doubt be considerably extended, as many if not

all the species occurring in the surrounding country are likely to extend into

the foothills. A few species additional to those noted below have previously

been recorded from the Fort Portal district, just outside the mountain area.

Anopheles implexus Theo. Kalinzu Forest (Jackson); Kibale Forest

(Edwards).

A. gambiae Giles. Kilembe.

A. marshalli var. gibbinst Evans. Nyakasura.

A. demeillont Evans. Nyakasura; Kilembe.

Megarhinus brevipalpis v. conradti Griinb. Buhundo.

Uranotaenia bilineata Theo., var. Kilembe. The specimens collected are

badly rubbed, but agree with the var. obsoleta Edw. in the faint rings and in-

distinctly pale tips of the hind tarsi. The type of var. obsoleta was from Kasa-

kiro, near Fort Portal. (Gibbins).

MOSQUITOES 33

Uranotaenia mashonaensis Theo. Kilembe, in small swampy patch of

forest, with the last.

U. shillitonits Edw. Nyakasura.

Taemorhynchus (Coquillettidia) fuscopennatus Theo., Mobuku_ Valley,

7300) it., I 6.

T. (C.) maculipennis Theo. Kilembe.

Aédes (Stegomyia) aegypti L. Kilembe.

A. (S.) stmpsoni Theo. Kilembe; larvae in leaf-axils of Colocasia.

A. (S.) apicoargenteus Theo. Kilembe, around hollow tree.

A. (S.) africanus Theo. Kilembe.

A. (Aédimorphus) tarsalis Newst. Kilembe.

A. (Aéd.) quasiunivittatus Theo. Mobuku Valley, 7300 ft., 1 3.

Culex nebulosus Theo. Kilembe; larvae in old wheelbarrow.

C. duttont Theo. Mobuku Valley, 1 ¢ at light.

C. anderson’ Edw. Kyanjoke Camp, Namwamba Valley; larvae in small

tree-hole with clear water near ground-level.

C. hopkinst Edw. Recorded from Kameranjoka (Hopkins).

C. trifilatus Edw. var. Kameranjoka (Hopkins).

C. musarum Edw. Nyakasura; also Mobuku Valley, larvae in leaf-axils

of wild banana.

C. kingianus Edw. Kilembe; adults in small swampy patch of forest.