SIMULIIDAE OF AFRICA 35 



Distribution. Widely distributed in all zoogeographical regions and present 

 almost everywhere on continental land-masses providing suitable watercourses exist 

 for the immature stages. Absent from New Zealand, Hawaii, Samoa and Tonga 

 and coralline islands. Present on following isolated islands : Azores, St. Helena, 

 Seychelles, Reunion, Mauritius, Rodriguez, Ryukyu Islands, Bonin Islands, Mariana 

 Islands, Caroline Islands, New Hebrides, New Caledonia, Fiji, Tahiti, Marquesas 

 Islands. Occurring also throughout East Indian Archipelago and New Guinea, in 

 Iceland, Greenland, Mediterranean islands, Madeira and Canary Islands. 



Discussion. Simulium, in the broad sense used here and accepted by the majority 

 of simuliid taxonomists, is by far the largest genus of Simuliidae and contains 

 several hundred species — probably amounting to three-quarters or more of the world 

 black-fly fauna. The genus falls into a number of segregates' distinguishable by 

 aggregates of characters taken in combination from the adult, pupal and larval 

 stages, and many of the segregates are currently recognized as named subgenera. 

 This course is considered to be the best taxonomic treatment possible, although it 

 has to be admitted that some subgenera are much more distinctive than others and 

 that they cannot all be distinguished by completely satisfactory characters in all 

 stages : some may be virtually inseparable from related subgenera in one sex or one 

 stage, although readily separated by obvious character differences in others. 



On a world basis there is as yet no completely worked out and universally applied 

 subgeneric classification for Simulium s.l. but at the present time it appears that the 

 world fauna may fall into some 30-35 subgenera, assuming segregates comparable to 

 those already recognized for the Holarctic faunae and recognized in the present 

 paper for the fauna of Ethiopian Africa and Malagasia. Most of the subgenera are 

 endemic to one or confined to two zoogeographical regions, only Eusimulium having 

 an almost cosmopolitan range. For Africa and its islands a total of 16 subgenera are 

 here recognized in the Simulium fauna : eight of these are confined to the Ethiopian 

 Region (Anasolen, Edwardsellum, Freemanellum, Lewisellum, Meilloniellum, Metom- 

 phalus, Phoretomyia and Pomeroyellum) and one to the Malagasy Region (Xeno- 

 simulium), one occurs only on St. Helena Island (Dexomyia), one is common to the 

 Holarctic and Ethiopian Regions (Byssodon) and one is cosmopolitan (Eusimulium) ; 

 the remaining four subgenera occur in Palaearctic Africa but are absent from 

 Ethiopian Africa (Wilhelmia, Odagmia, Simulium s. str., Tetisimulium) and of these 

 four all except Simulium s. str. are confined to the Palaearctic Region (Simulium 

 s. str. is present also in the Nearctic and Oriental Regions). Keys for the recognition 

 of the sixteen subgenera occurring in the African area are given below for both sexes 

 and for the pupal and larval stages. 



One species occurring in Morocco, Simulium gracilipes Edwards, is known only 

 from the female holotype and is subgenerically unplaceable (see Crosskey, 1965 : 

 667) ; it may belong to the Palaearctic subgenus Schoenbaueria Enderlein but this 

 cannot be confirmed on the female alone. However it is possible that future 

 collecting in North Africa may show the presence of this subgenus in the area here 

 covered. 



Species of Simulium s.l. from other zoogeographical regions sometimes show 



