SIMULIIDAE OF AFRICA 15 



Pupae 



1 Last abdominal segment with a pair of very long strong terminal hooks (Text-figs. 42- 



44). Abdominal cuticle with distinctly sclerotized tergal and sternal plates, con- 

 spicuous by pale yellowish brown colour in cast pupal pelt. Sides of abdomen 

 often with discretely formed pleurites. Mid venter of segments 6 and 7 (sometimes 

 also 8) with semi-membranous longitudinally striate areas dividing the sternal 

 plates. PROSIMULIUM Roubaud (p. 17) 



- Last abdominal segment without long terminal hooks but with a pair of very small 



blunt or at most slightly thorn-like tubercles. Abdominal cuticle forming mainly 

 a delicate transparent pellicle without strong sclerotization, cast pupal pelt showing 

 brownish plates only on the last segment or weakly on the dorsum of the first few 

 segments. Abdomen without pleurites. Mid venter of segments 6-8 without 

 conspicuous longitudinally striate area ........ 2 



2 Sides of last two abdominal segments with complex biramous anchor-like spinous 



hooklets, sometimes variously multifid (Text-fig. 35). Gill arborescent. [North 

 Africa]. . METACNEPHIA gen. n. (p. 26) 



- Abdomen completely without anchor-like hooklets. Gill of varied form ... 3 



3 Gill with three elongate tapering and flattened branches (Text-figs. 223). Abdominal 



dorsum without spine-combs. [Southern Africa only] 



AFROSIMULIUM gen. n. (p. 30) 



- Gill not of this form (except in some Byssodon). Abdominal dorsum with or without 



spine-combs on segments 6-9. [Widespread throughout area] 



SIMULIUM Latreille (p. 34) 



Larvae 



[Note: the larva of Afrosimulhim is unknown and the generic key cannot therefore be complete 

 for the larval stage] 



1 Postgenal bridge incomplete, divided by long anteriorly tapering postgenal cleft that 



broadly reaches the hypostomium (Text-fig. 36). [North Africa] 



METACNEPHIA gen. n. (p. 26) 



- Postgenal cleft not broadly reaching the hypostomium, postgenal bridge therefore 



complete medially even if reduced to narrow strip ...... 2 



2 Hypostomium with large, often rather fusiform, teeth aggregated into three main 



groups (Text-figs. 46, 49-52), sometimes only median tooth very prominent (Text- 

 fig- 53)- Cervical sclerites merged with upper ends of postocciput in band of 

 continuous sclerotization (Text-fig. 20). Mandible with third comb-tooth enorm- 

 ously enlarged (Text-figs. 54, 55) and inner edge usually with long saw-like series of 

 mandibular serrations. Maxilla with conspicuous dark dense hair tuft near base of 

 palp (Text-fig. 56). Cephalic apotome with positive head-spots and widest some 

 way before hind margin (Text-fig. 48). Third antennal segment much darker 

 pigmented than remainder of antennae (Text-fig. 47). Abdominal cuticle bare. 

 Rectal gills simple PROSIMULIUM Roubaud (p. 17) 



- Hypostomium not of this form, teeth not exceptionally produced and usually not so 



aggregated. Cervical sclerites discrete and isolated from postocciput (Text-fig. 21). 

 Mandible with third comb-tooth not enlarged like this and inner edge without saw- 

 like series of serrations (almost always two serrations, rarely reduced to one or 

 obliterated, very rarely one or two supernumerary serrations). Hair tuft of 

 maxilla near base of palp pale, sparse and very inconspicuous. Third antennal 

 segment normally not more strongly pigmented than other parts of antenna. 

 Abdominal cuticle bare or setose. Rectal gills simple or compound. Cephalic 

 apotome with positive or negative spots, broadest near posterior margin (a few 

 exceptions) ....... SIMULIUM Latreille (p. 34) 



