76 R. W. CROSSKEY 



treatment of these subgenera ; from the Oriento-Australasian subgenera Gom- 

 phostilbia and Morops it is distinguished by almost all the characters separating 

 these from Pomeroyellum already given. 



One species of the subgenus, Simulium (M eilloniellum) adersi Pomeroy, is unique 

 among all the more ' primitive ', or at least less specialized, Ethiopian species of 

 Simulium (those in subgenera Eusimulium, Pomeroyellum and M eilloniellum) in hav- 

 ing the pleural membrane haired ; all other characters however confirm the position 

 of adersi in M eilloniellum. 



Attention should be drawn to the nature of the setae on the larval abdomen. 

 For brevity, these have been described in the diagnosis and foregoing discussion as 

 simple spinous setae but the actual shape is slightly fusiform or very narrowly 

 lanceolate as the setae are slightly widened near the middle from which they taper 

 to a point (well shown by Garms & Post, 1967, fig. 7L). 



Included taxa. Simulium (M eilloniellum) adersi Pomeroy ; S.(M.) hirsutum 

 Pomeroy ; S.(M.) sexiens de Meillon ; S.(M.) urundiense Fain. 



Subgenus LEWISELLUM sgen. n. 



Type-species : Simulium neavei Roubaud, 1915. 



Diagnosis, o"? : Basal section of radius haired. Pleural membrane bare. Katepisternum 

 bare. Fore tarsus not dilated, about 5-25-7 times as long as its greatest breadth. $ : cibarium 

 unarmed. Tarsal claws with small or minute basal tooth, sometimes virtually simple. Scutum 

 without pattern. Abdomen thickly covered with scales*. Seventh sternite usually distinct. 

 Gonapophyses simple bluntly rounded lobes. Paraprocts normal. Spermatheca without sur- 

 face pattern or internal hairs, o" : scutum without pattern. Genitalia with small styles much 

 shorter than coxites, style abruptly narrowed on about apical third and with one spinule ; 

 coxite not produced beyond base of style ; ventral plate not toothed, with large rounded 

 shoulders and median apical U-shaped notch (Text-fig. 105), basal arms very small and directed 

 more or less forwards ; median sclerite a large broad elongate band, parallel-sided or slightly 

 constricted medially ; paramere small tapering subtriangular, one long very strong outwardly 

 directed parameral hook (Text-fig. 89). Pupa : Gill filamentous, eight long slender sinuous 

 filaments arising near base and branching in 3 + 3 + 2 arrangement (Text-fig. 195) ; gill as long as 

 or longer than pupal body. Abdomen with normal basic onchotaxy and in addition with a row, 

 usually of four, of small hooklets each side dorsally on segment 2 and some supernumerary min- 

 ute hairs dorsally or dorsolaterally on segments 1, 2, 5 and 6, also one or two supernumerary 

 dorsal hairs on hooklet-bearing segments 3 and 4 ; ventrally segment 4 with pair of small hook- 

 lets (in addition to normal two pairs of ventral hooks on segments 5-7) ; terminal segments 

 dorsally without definite spine-combs, or with trace of rudimentary combs on segments 7 and 8. 

 Cocoon simple, without neck or median projection. Larva : Head atypically elongate and 

 cephalic apotome unusually parallel-sided (Text-fig. 283), posterior corners of cephalic apotome 

 evenly rounded ; cephalic fans normal. Hypostomium atypical in older and mature larvae, 

 with subequal teeth numbering thirteen in apical row and with lateral margins less strongly con- 

 vergent than normal (Text-fig. 268) ; hypostomial setae 4-7 in each row, rows lying parallel to 

 lateral margins of hypostomium. Head-spots negative, on cephalic apotome delimited by 

 darker pigmentation forming H-shaped mark (Text-fig. 283), apotome sometimes rather evenly 

 pigmented and spots indefinite. Postgenal cleft small, quadrate, much shorter than postgenal 

 bridge (Text-fig. 251). Mandible atypical, long and slightly tapering with outer edge less arched 



* See Appendix 



