Amencan Museum

ovitates

PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY

CENTRAL PARK WEST AT 7QTH STREET, NEW YORK 24, N.Y.

NUMBER 1956 AUGUST 5, 1959

Sibling Species of Trigona from Angola

(Hymenoptera, Apinae)!

By CHARLES D. MICHENER

Recently a considerable amount of biological work has been pub-

lished concerning small West African bees of the subgenus Hypoirt-

gona, at first identified as Trigona gribodoi Magretti, and later, thanks

to Guiglia’s (1955) clarification of the characters of that species, as

T. braunst Kohl. Every recent paper concerning the biology of these

bees has referred to two forms. These forms are clearly distinguished

by the natives of Angola, who have different names for them in their

languages. Because Portugal-Aratjo and Kerr (in press) have shown

them to be sympatric and reproductively isolated, these forms must

represent distinct species. The taxonomic necessities are provided here

in order that those authors can satisfactorily present their data on

reproductive isolation and allied matters.

The two species herein segregated differ from other African Hypo-

trigona by the dull, finely and very closely punctate mesoscutum and

scutellum, the latter but little more shining and more finely punctate

than the former. In other species the scutellum is distinctly more

shining than the mesoscutum.

The separation of these species (braunsi, sensu lato) from gribodot

Magretti was indicated by Kohl (1894) but was not properly docu-

mented until Guiglia (1955) compared type material of braunsi and

gribodoi, tabulated the differences, and gave photographs of the pos-

terior legs. Meanwhile, the differences between them were often re-

1 Contribution Number 1024 from the Department of Entomology of the Uni-

versity of Kansas, Lawrence, Kansas.

2 AMERICAN MUSEUM NOVITATES NO. 1956

garded as inconsequential and not of specific value (Cockerell, 1934;

Schwarz, 1948). It now becomes apparent that one of the species

(braunsi) so recently differentiated by Guiglia is itself composite, as

shown below.

The following characters are important features of workers of both

braunsi and its sibling, described below as araujot: scutellum opaque,

punctation not much different from that of mesoscutum; posterior

margin of hind tibia more strongly rounded apically than elsewhere,

not angulate apically; metatarsus broader at or beyond middle than

basally.

Trigona (Hypotrigona) braunst Kohl

Trigona braunsi Kon., 1894, p. 280. Frizsz, 1909, p. 456. Guieiia, 1955,

p. 310.

Trigona gribodot form cassusso PoRTUGAL-ARAUJO, 1955a, p. 108; 1955b,

p- 25; 1956, p. 10.

Trigona braunsi form cassusso PORTUGAL-ARAUJO, 1958, pp. 203-211.

This form, known as nanga in the Bacongo dialect and as cassusso

in the Kimbundu dialect, is the smaller of the two sibling species. For-

tunately the photograph of the leg of a cotypical worker by Guiglia

(1955) shows the one significant structural difference between braunsit

and araujot (shape of basitarsus) so that no doubt exists as to which

of the species should have the name braunsi. Kohl’s measurements

(length 2.5 to 8 mm.) support this conclusion.

The differences between this species and araujoi are indicated in

table 1.

The species was described from the Cameroons, and specimens before

me are from Dande and Luanda, Angola. Other records (see Friese,

1909) may or may not relate to braunsi, sensu stricto.

Trigona (Hypotrigona) araujoi, new species

Trigona gribodot form landula PorTUGAL-ARAUJo, 1955a, p. 105; 1955b,

p. 24; 1956, p. 9.

Trigona braunsi form landula PorTUGAL-ARAUJO, 1958, pp. 203—211.

This species is distinguished by the natives from braunsz. It is known

as brussuso in the Bacongo dialect and as landula in the Kimbundu

dialect. It is not only larger than its close relative, braunsi, but is

larger than other African Hypotrigona.

This species is named for Virgilio de Portugal-Araujo of Luanda,

Angola, who first published on the biological distinctions between

the forms here separated as species. It is unlikely that the species would

have been recognized except for the biological differences; at least the

1959 MICHENER: 'TRIGONA 3

two principal taxonomic specialists on Trigona in the world did not,

after examining specimens, regard it as distinct from braunsi (or even

gribodot) in spite of the biological differences established by Portugal-

Araujo.

Trigona (Hypotrigona) araujoi differs from braunst by the characters

listed in table 1.

TABLE 1

DIFFERENCES BETWEEN Two SIBLING SPECIES OF Trigona*

Landula

Trigona araujot,

new species

Cassuso

Trigona braunst Kohl

Entrance of nest 3-4 mm. in diameter; 2-5 10 mm. in diameter; 5-7

cm. long cm. long

Usual colony population 400-600 2000-2500

Arrangement of brood cells In clusters Vertical layers

Honey and pollen pots 5 by 5 mm. 7 by 10 mm.

Temperament Aggressive when first dis- Gentle

turbed

Defense of colony Pouring honey into entrance Fighting

Robbed by Lestrimelitta

cubiceps Commonly Rarely

Length 2.5-3 mm. 3.2-4 mm.

Head width 0.54-0.63 mm. 0.67-0.74 mm.

Scutellum Slightly more shining an- As dull as mesonotum

teriorly than mesonotum

Hind basitarsus Widest beyond middle (fig. 1) Widest medially (fig. 1)

Hamuli® 5 6

*The biological differences listed are the more obvious features extracted from the

publications of Portugal-Aradjo (1955a, 1955b, 1956, 1958). The structural features

are based on workers.

’This character was found by Alvaro Wille of the University of Kansas. One speci-

men of araujoi had five hamuli on one wing; perhaps one was broken off.

Type MATERIAL: Holotype (worker) and 46 paratypes (workers):

Luanda, Angola, December 10, 1957; V. de Portugal-Araujo. Thirty

paratypes (workers): Dande, Angola, December 10, 1957; V. de Portu-

gal-Araujo.

The holotype and various paratypes will be deposited in the collection

of the American Museum of Natural History. Paratypes will be placed

in the Snow Entomological Museum, University of Kansas; the British

Museum (Natural History); and the collection of J. S. Moure, Curitiba,

Parana, Brazil.

4 AMERICAN MUSEUM NOVITATES NO. 1956

Fic. 1. Outer surfaces of hind tibiae and tarsi of workers of Trigona braunst

(small) and T. araujoi (large), lighted to show shape (left) and pubescence

(right).

Because the principal non-behavioral difference that has been found

between T. braunst and T. araujoz is size, measurements of head widths

of 147 workers of the former and 83 workers of the latter were made.

This feature was selected for study simply because it is easily measured.

NUMBER OF

i 3 5 7 9 ON 1 8 W 9 2 23 25 27 29 31

HEAD WIDTH

Fic. 2. Histograms to show differences in size between workers of T. braunsi

and those of T. araujot. Measurements were of the total width of the head.

The scale on the abscissa is an arbitrary one, in which each division equals

0.0064 mm., starting with 1 = 0.5440 mm. The widths of the head, in the

series measured, vary for braunsi from 0.5440 to 0.6272 mm.; for araujoi,

from 0.6656 to 0.7360 mm.

1959 MICHENER: TRIGONA 5

Figure 2 shows that no overlapping in head width was found between

the two species. Sizes of most other structures would probably be

equally distinctive. Measurements were made from workers from seven

colonies of braunsi and four of araujoi; within a species, intercolony

differences were negligible.

ACKNOWLEDGMENTS

I am entirely indebted to Mr. Virgilio de Portugal-Araujo of Luanda,

Angola, for the material on which this paper is based and to him and

Dr. Warwick E. Kerr of the Escola Superior de Agricultura “Luiz de

Queiroz,” Piracicaba, Sdo Paulo, Brazil, for encouragement to prepare

this paper.

LITERATURE CITED

CocKERELL, T. D. A.

1934. Some African meliponine bees. Rev. Zool. Bot. Africaines, vol. 26,

pp. 46-62.

FRIESE, H.

1909. Die Bienen Afrikas. Jn Schultze, L., Zoologische und Anthropolo-

gische Ergebnisse einer Forschungsreise im westlicken und zentralen

Siidafrika. Jena, Gustav Fischer, vol. 2, pp. 83-476, pls. 9-10.

GUIGLIA, DELFA

1955. Missione del Prof. Giuseppe Scortecci in Migiurtinia, Hymenoptera.

Ann. Mus. Civ. Stor. Nat. Genova, vol. 68, pp. 306-311, pl. 6.

Kou, F.

1894. Zur Hymenopterenfauna Afrikas. Ann. Naturhist. Hofmus. Wien,

vol. 9, pp. 279-350.

PORTUGAL-ARAUJO, VIRGILIO DE

1955a. Notas sdbre colénias de meliponineos de Angola—Africa. Dusenia,

vol. 6, pp. 97-114.

1955b. Colmeias para “abelhas sem ferrdo.” Bol. Inst. Angola, no. 7, pp.

9-34, figs. 1-30.

1956. La culture des mélipones et son introduction en Europe. Luanda,

Instituto de Angola, pp. 1-11 (mimeographed; printed cover).

1958. A contribution to the bionomics of Lestrimelitta cubiceps (Hymen-

optera, Apidae). Jour. Kansas Ent. Soc., vol. 31, pp. 203-211.

PorTUGAL-ARAUJO, VIRGILIO DE, AND WARWICK EstTEVAM KERR

{in press.] A case of sibling species among social bees.

ScHWARzZ, H. F.

1948. Stingless bees (Meliponidae) of the Western Hemisphere. Bull.

Amer. Mus. Nat. Hist., vol. 90, pp. i-xviii, 1-546.