SIMULIIDAE OF AFRICA 27 



strate, covering pupal body and often entirely concealing gills. Larva : Head not noticeably 

 convex, cephalic fans present and normal. Cephalic apotome broadest near hind margin or 

 slightly forward. Head-spots positive or pigmentation pattern not definitely classifiable. 

 Postgenal cleft large and elongate, almost subparallel-sided or tapering anteriorly and broadly 

 reaching base of hypostomium, postgenal bridge therefore widely incomplete (Text-fig. 36). 

 Hypostomium characteristic (Text-fig. 37), apical teeth very reduced and inconspicuous, 

 anterior corners of hypostomium unusually rounded. Mandible with three or four mandibular 

 serrations that form together an expanded serrate flange on inner edge of mandible. Cuticle 

 bare. Ventral papillae absent and last abdominal segment without sclerotized accessory ring. 

 Anal sclerite normal. Rectal gills simple. 



Distribution. Nearctic Region (mainly from Manitoba to Alaska and in western 

 United States) and Palaearctic Region (from western Europe and North Africa to 

 eastern USSR, including northern Iran). 



Discussion. The Simuliid fauna of North Africa (Morocco : see Grenier et al., 

 1957) contains two of the species that belong in the taxonomically troublesome 

 miscellany of forms that have up to now been assigned to the genus Cnephia, despite 

 the fact that many of them share few characters in common with those of Cnephia 

 pecuarum (Riley), the type-species of Cnephia, from the Mississippi. Consideration 

 of the characters shown by the species known from Morocco (blanci Grenier & 

 Theodorides and tredecimatum Edwards), while preparing the present revision of 

 African Simuliidae, showed that although they obviously fitted exactly into Rubzov's 

 (1959-1964) pallipes-group of Cnephia this group as a whole was very disjunct in its 

 characters from those of the true Cnephia as shown by the type-species, and that the 

 genus ' Cnephia ' as treated by Rubzov or the subgenus ' Cnephia ' in the sense of 

 Stone (1965 : 184) contains an admixture of forms that fall clearly into two quite 

 separate categories. The two facies are so clear cut that it is difficult to accept that 

 there is any close relationship between the segregates, and — equating the combina- 

 tions of characters with those shown by other genus-group segregates in the 

 Simuliidae — I do not think it possible to treat both as consubgeneric or even as 

 congeneric as recent authors have done without bringing in to the same named 

 segregate forms that are (I believe it fair to judge) clearly polyphyletic. The degree 

 of difference found in the two groups of ' Cnephia ' auct. may be gauged from the 

 following tabulation of the characters involved : 



A. Mesepisternal sulcus wide and shallow, evanescent anteriorly, katepisternum as deep as its 



length in profile. Last segment of maxillary palp subcylindrical, short and usually 

 subequal to third segment. Pleural membrane bare. Female gonapophyses slightly 

 but distinctly produced tongue-like. Pupal abdomen with long strong terminal hooks 

 and without biramous or trifurcate anchor-like or grapnel-like hooks. Cocoon feeble, 

 usually irregular bag-like without well defined anterior rim. Larval head with post- 

 genal bridge complete, broad, postgenal cleft subequal in length to or shorter than post- 

 genal bridge. 



B. Mesepisternal sulcus sharply defined, deep though sometimes wide, almost complete 



anteriorly, katepisternum in profile longer than its depth. Last segment of maxillary 

 palp elongate, almost always much longer than third segment. Pleural membrane 

 haired (a few exceptions). Female gonapophyses bluntly truncate. Pupal abdomen 

 without long terminal hooks (with pair of small blunt tubercles), and with complex 



