SIMULIIDAE OF AFRICA 65 



The Japanese species aforementioned have been placed by Rubzov (1959-1964 : 

 308-312) in his batoense-group of Eusimulium, but batoense Edwards has the 

 characters of the subgenus Gomphostilbia, a weakly-defined subgenus near to 

 Eusimulium but considered distinct in an earlier paper (Crosskey, 1967a). In that 

 paper, the three Japanese species in which the katepisternum is haired and the pupal 

 gill has eight filaments, viz. S.(G.) omntaense Ogata & Sasa, S.(G.) shogakii (Rubzov) 

 and S.(G.) ogatai (Rubzov), were removed from Eusimulium and placed in Gompho- 

 stilbia, where it is here considered that they should be assigned ; but the other 

 three Japanese species in Rubzov's batoense-group (mie, yamayaense and sasai 

 mentioned above) have the katepisternum bare and 4 or 6 filaments in the pupal 

 gill, and these remain best placed in Eusimulium near to the loutetense-group as 

 here defined. Nevertheless it must be recognized that those forms of Eusimulium 

 with many parameral hooks, with six or eight gill filaments, and with a large pointed 

 larval postgenal cleft, approach closely to those forms placed in Gomphostilbia and 

 that their characters are intermediate between those of typical Eusimulium and 

 Gomphostilbia. It would be possible to widen the definition of Eusimulium, sink 

 Gomphostilbia in synonymy, and treat the species now placed in Gomphostilbia as a 

 species-group of Eusimulium, but Eusimulium is more discretely defined if the 

 Gomphostilbia segregate is excluded : it is here preferred to treat Gomphostilbia as a 

 valid subgenus close to Eusimulium, showing possible affinity with the loutetense- 

 group. 



The two Ethiopian species {rutherfoordi and narcaeum) placed in the same group 

 with loutetense have the female claw-tooth strongly developed (as do the Japanese 

 species cited above), whereas in loutetense itself the claw-tooth is extremely reduced : 

 the size of the claw-tooth is not used as a diagnostic character for the loutetense- 

 group. Furthermore these two species have the pupal gill with four filaments and 

 the cocoon a simple pocket without trace of neck, the pupal stage thus closely 

 resembling the ruficorne-group. The spermatheca of the female in all three species 

 has a hexagonal reticulate pattern, as normal in subgenus Eusimulium. 



The loutetense-group is unknown from the Malagasy Region. 



Included taxa. Ethiopian Region : S.(E.) loutetense Grenier & Ovazza ; S.(E.) 

 narcaeum de Meillon ; S.(E.) rutherfoordi de Meillon. Nearctic Region : S.(E.) 

 furculatum (Shewell). 



aureum- group. Postnotum with patch of scales on each side. Style very small in relation 

 to coxite, constricted and twisted (Text-fig. 142) ; ventral plate not lamellate, with small sub- 

 triangular body and very large widely divergent and outwardly directed basal arms (Text-fig. 

 102) ; parameres long and narrow, with one long strong parameral hook ; median sclerite in 

 form of very long slender rod, sometimes frayed at tip. Pupal gill with 4 filaments, long and 

 slender. Cocoon a simple pocket without anteromedian projection. Larval antenna without 

 secondary annulations, larval mandible without supernumerary serrations. Larval postgenal 

 cleft small and quadrate, much shorter than postgenal bridge. 



Simulium {Eusimulium) aureum Fries is type-species of Eusimulium and this 

 discrete and very uniform group is nomenclaturally the typical species-group in 

 subgenus Eusimulium. The males of aureum-group species are, however, somewhat 



