34 R. W. CROSSKEY 



upon the importance to be attached to the exceptional head and wing characters, 

 which make gariepense difficult to assign satisfactorily to any of the existing genera : 

 if it is not placed in a new genus then it would have to be assigned to Simulium, and 

 it could possibly be treated as an aberrant subgenus within Simulium s.l. I have 

 been uncertain as to which is the better course but have decided that, until garie- 

 pense becomes better known through discovery of its larval stage and biology (when 

 re-assessment of its genus-group status might be made), it is best to place it as a full 

 genus distinct from Simulium. 



Included taxon. Afrosimulium gariepense (de Meillon) comb. n. 



SIMULIUM Latreille 



Simulium Latreille, 1802 : 426. Type-species : Rhagio colombaschensis Fabricius, 1787, by 

 monotypy. 



Diagnosis. 0*$ : Antenna with 11 segments (very rare exceptions with 10 or 12). Head and 

 eyes normal, latter rarely somewhat reduced in $. Last segment of maxillary palp elongate, 

 conspicuously longer than either of the two preceding segments (rare exceptions). Pleural 

 membrane bare or haired. Mesepisternal sulcus narrow and deep, sharply defined and complete. 

 Katepisternum bare or haired, in profile longer than its depth. Costa with spiniform and hair- 

 like macrotrichia. Vein Rs simple, Cut sinuous. Basal cell absent, or vestigial. Basal section 

 of radius bare or haired. Wing membrane with normal microtrichia. Fore tarsus slender or 

 dilated. Calcipala large (except in Neotropical Andean subgenus Pternaspatha Enderlein). 

 Pedisulcus present, o" : hypopygium with styles and ventral plate of extremely varied form, 

 ventral plate sometimes toothed; style usually with one apical spinule, spinules multiple in a 

 few forms ; parameral hooks very varied, usually many but sometimes only one strong hook 

 each side, sometimes completely vestigial ; median sclerite very varied. $ : cibarium unarmed 

 or with pointed teeth or blunt granulations between cornuae. Claws with or without basal 

 tooth. Gonapophyses varied, sometimes produced into pointed or tapering curled processes. 

 Pupa : Gill of immensely varied form. Abdominal cuticle membranous, without clearly 

 sclerotized terga or sterna and without conspicuous pleural plates or pleurites, abdomen of cast 

 pupal pelt almost entirely pale transparent (except parts of last segment), at most weak pale 

 brownish tergal sclerotization anteriorly ; no longitudinally striate areas. Last segment with blunt 

 terminal tubercles, these at most slightly thorn-like. Abdominal onchotaxy with almost constant 

 basic plan (segments 3 and 4 dorsally each with four hooks each side, segments 5-7 ventrally each 

 with two hooks on each side of which those on segment 5 close together and those on 6 and 7 

 well separated), but aberrant forms of onchotaxy occur (mainly in phoretic forms) ; dorsum of 

 abdomen with or without backwardly-directed spine-combs on some segments. Cocoon well 

 formed, of discrete shape, with or without neck, sometimes with anterodorsal projection, some- 

 times reduced to cover only pupal abdomen. Larva : Head with cephalic fans, head shape 

 usually not strongly convex. Cephalic apotome broadest near posterior margin (some excep- 

 tions in which broadest near middle or well forward). Head pattern positive, negative or un- 

 classifiable. Postgenal cleft of very varied form, sometimes absent, rarely reaching hypostom- 

 ium. Hypostomium almost always with row of nine apical teeth with only middle tooth and 

 each corner tooth slightly prominent (varied bizarre exceptions occurring, mainly in island or 

 phoretic forms). Mandible varied, nearly always with two serrations on inner margin but these 

 sometimes obliterated or accompanied by one or two supernumerary serrations. Cuticle bare or 

 with setae of various forms and extent of distribution. Ventral papillae present or absent, last 

 abdominal segment almost always without definite accessory ring. Anal sclerite normal X- 

 shaped. Rectal gills simple or compound. 



