906 REPORT OF THE HARVARD AFRICAN EXPEDITION 
dae, it is risky to make any general statement with regard to distribution, it 
would seem that only Atelozella, Ancala, and Euancala are strictly Ethiopian, 
the remaining groups being found also in other parts of the world. 
Key To THE Species or Tabanus OF THE BELGIAN CONGO 
In his Monograph of African Tabanus (1909), Surcouf has arranged the 
Ethiopian species into sixteen groups. Some of these are rather well defined and 
partly correspond to the subgenera defined above. Thus his first group covers 
Ancala Enderlein; his fourteenth and most of his sixteenth groups belong in 
Atylotus Osten Sacken, one species of his sixteenth group being a T’hervoplectes; 
and his fifteenth group is Ewancala Enderlein. His remaining twelve groups 
are based mainly upon combinations of the relative width of the frons, the shape 
of the frontal callosities, and the abdominal markings. They are rather poorly 
defined so that certain species may well be sought for in two or more of these 
groups. Moreover, his grouping has the great disadvantage of placing in differ- 
ent groups species that are undoubtedly related. 
So far as the species of the Belgian Congo are concerned, I have found it 
more practical to divide the Tabanus, proper, into two groups only, viz., (1) those 
with uniformly colored abdomen, and (2) those with the abdomen marked in 
various ways with spots or stripes. Even so, 7. biguttatus Wiedemann and 7. 
xanthomelas Austen may be placed in either group, since the abdomen may be 
spotted or unspotted.! 
iby Ponerinae mmebr es wollen. b.).Aisix as Aeesteve « Sot ane 2 aeeicelienne ar ener ee eee aoe tera De 
Heredibise normal or but slightly wadented 4. n<s sa aoe aes sce ey ee en 3. 
2. Wing speckled black and hyaline; fork of third longitudinal vein with appendix. 
OCH A GRO TUCCUD) ow bo ny Bes a Sree Siege Outer Ue Ee ne Ge: 
Wing hyaline with transverse dark bands; fork of third longitudinal vein without ap- 
pends, “Groupas <GAyiola).. ji... << 2av is 5 yee skis aes ae ee 8. 
3. Eyes densely pubescent. Vertex slightly raised and often with a median longitudinal de- 
pression, but without shiny callosity. Group C (Thertoplectes) ................. ae 
Eyes bare or pubescent. Vertex either with a shiny, well-defined callosity or entirely flat: 4. 
4. Eyes more or less pubescent. Vertex with a well-defined, often shiny callosity; the 
frontal callosity well-developed. Group D (Sziladynus)............. 0.020000 0 0. ibe? 
Eyes bare or pubescent. Vertex without callosity and not appreciably raised......... DE 
5. Eyes more or less pubescent, sometimes very faintly so in the female. Frons with the 
basal callosity either reduced to a small shiny spot, vestigial, or absent; sometimes 
with a small, disconnected median spot above it. Group E (Atylotus)............ lee 
Eyes bare. Basal callosity of the frons always well-developed, large; the median frontal 
callosity distinct, sometimes free, more often connected with the basal callosity. 
TOUT SeIMO TOD Nh ned, ind 5's “os whut, v4. tected. & Teer ig Gad ages ck ee eevee te ee 6. 
6. Abdomen (in well-preserved specimens) uniformly colored, without spots or bands of pale 
pubescence; rarely darker in the middle basally. Group F..................... 14. 
Abdomen with dark markings on a pale background, or with pale spots or bands of 
pubescence or pruinosity on a dark background (sometimes covering entire segments 
or RECUGed Go Tait Imes or spots), GrouprG...<ied.ah » feaaless owe over ae ees Die 
1 The present key is based primarily on the females. The males are as yet unknown for many 
species and are often difficult to correlate with the opposite sex. In most cases, though, my key will in- 
dicate the affinities of the males, even when their specific identity is left in doubt. 
2 Badly preserved specimens of 7’. secedens, T. socialis, T. coniformis and similar species often 
appear as if with unspotted abdomen. 
