SIMULIIDAE OF AFRICA 43 



numerous hooks (from 110-300 rows of 18-49 hooks). Antennae short (Text-fig. 



288), usually not longer than stem of cephalic fan . . . . . . n 



9 Head-spots positive (Text-figs. 235, 236). Cuticle bare or at most with minute 

 colourless and very inconspicuous simple hairs. Postgenal cleft very small, much 

 shorter than postgenal bridge (Text-figs. 241-244) (except in louletense-group, 

 Text-fig. 245) EUSIMULIUM Roubaud (p. 56) 



- Head pattern negative, on cephalic apotome pale spots separated or surrounded by 



dark pigmentation that often forms an H-shaped mark (Text-figs. 232-234). 

 Cuticle at least of the abdomen with simple or variously modified setae (except 

 bare in bequaerti-group) . Postgenal cleft normally longer than or at least sub- 

 equal in length to postgenal bridge (Text-figs. 246-250) ..... 10 



10 Abdominal cuticle posterodorsally with sparse minute simple or at most slightly 



fusiform setae. Postgenal cleft large and rounded-subcordate (Text-fig. 250). 

 Ventral papillae sometimes rounded and small, rather inconspicuous 



MEILLONIELLUM Rubzov (p. 74) 



- Abdominal cuticle posterodorsally with large erect scales or small more recumbent 



divided setae (of shapes shown in Text-fig. 225), bare in bequaerti-group. Post- 

 genal cleft variously shaped but not of this form. Ventral papillae subconical, 

 well developed POMEROYELLUM Rubzov (p. 66) 



11 Abdominal cuticle bare. Primary brush of the mandible exceptionally prominent 



beyond end of mandible, often strongly arched (Text-figs. 295, 296). Main apical 

 tooth of mandible unusually reduced in size relative to other teeth (Text-figs. 301, 

 302), not noticeably stronger than or even smaller than comb-teeth. Sides of hypo- 

 stomium (outside the rows of setae) broadly expanded and hypostomial teeth very 

 reduced (Text-figs. 276, 277) ......... 12 



- Abdominal cuticle, at least posterodorsally, with small scales (Text-figs. 228, 229) or 



with minute scattered simple setae (Text-figs. 226, 227). Primary brush of 

 mandible normal, not projecting far beyond apex (Text-fig. 294). Main apical 

 tooth of mandible of normal large size, conspicuously larger than comb-teeth and 

 other apical teeth (Text-fig. 300). Sides of hypostomium less widely dilated and 

 hypostomial teeth less reduced (Text-figs. 275, 278-280) . . . . . 13 



12 Rectal gills with numerous finger-like secondary lobules. Antenna four-seg- 



mented, without secondary annulations. Postgenal cleft large and mitre-shaped 

 (Text-fig. 254), much longer than postgenal bridge. [Ethiopian Region only] 



FREEMANELLUM sgen. n. (p. 92) 



- Rectal gills simple trilobate, without secondary lobules. Antenna with 6-8 apparent 



segments because of secondary annulation (Text-fig. 290). Postgenal cleft 

 smaller and more pentagonal (Text-fig. 255), not longer than postgenal bridge. 

 [Malagasy Region only] .... XENOSIMULIUM sgen. n. (p. 86) 



13 Postgenal cleft very small, much shorter than postgenal bridge and forming a sub- 



quadrate or slightly pentagonal notch (Text-fig. 253). Hypostomial setae 

 numerous, 8-24 (usually 12-18) in each row. Abdomen only with simple setae 

 (these so small and sparse that superficially abdomen may appear bare). Rectal 

 gills always with many secondary lobules . . . ANASOLEN Enderlein (p. 88) 



- Postgenal cleft large and much longer than postgenal bridge, broadly sagittate, sub- 



cordate or subcircular (Text-figs. 256-258, 260). Hypostomial setae usually 

 fewer, 3-10 in each row. Abdomen with simple setae or with small flat scale-like 

 setae (Text-fig. 229). Rectal gills simple or compound 



METOMPHALUS Enderlein (p. 96) 



14 Abdomen with subconical ventral papillae. Postgenal cleft much shorter than post- 



genal bridge, usually forming only a small subquadrate notch in posteroventral 

 head margin (Text-fig. 241). Middle comb-tooth of mandible shorter than either 

 first or third. Pupal gill histoblast with four filaments EUSIMULIUM Roubaud (p. 56) 



