go R. W. CROSSKEY 



Continent. In southern Africa and in West Africa, where land levels in general are 

 lower than in East Africa and Ethiopia, Anasolen species occur at much lower 

 altitudes of 2,500-5,000 feet, but with the same ecological restriction to cascade 

 conditions. As with certain species of the subgenus Metomphalus, the smooth 

 submerged rock surfaces under the cascading water often appear black from the 

 enormous numbers in which Anasolen larvae and pupae thrive there. 



The subgenus Anasolen, though rather clearly related to Freemanellum sgen. n. 

 (also from the Ethiopian Region) and to Xenosimulium sgen. n. (from the Malagasy 

 Region) is an isolated segregate of Simulium s.l. showing no evidence of close 

 affinity with any subgeneric segregate in the Holarctic, Oriental or Australasian 

 Regions. Outside of the African area the relationships appear to lie most closely 

 with the subgenus Grenierella Vargas & Diaz Najera from South America, or at least 

 with the type-species of this subgenus, S.(G.) lahillei Paterson & Shannon : in the 

 absence of a complete revision of the segregates of Neotropical Simulium it is 

 difficult to make a satisfactory comparison, but it is here considered that Grenierella 

 can tentatively be accepted as a valid subgenus (Stone, 1963, places Grenierella as 

 a synonym of Chirostilbia Enderlein but there seems as yet insufficient evidence for 

 this) having many characters in common with, and probably phyletically close to, 

 African Anasolen. The larval and pupal stages of Grenierella, judging from the 

 excellent figures of lahillei given by Wygodzinsky (1949), do not appear to differ 

 subgenerically from those of Anasolen, and have for instance the following characters 

 conforming with those of the latter group : similar larval body shape with extremely 

 numerous hooklet rows in the circlets, no ventral papillae, similar hypostomium, 

 hypostomial setae, antennae and mandibles, and similar rectal gills, cocoon with 

 long very well formed neck, similar form of stiff gill branches with pointed tips, 

 similar lack of spine-combs dorsally on the pupal abdominal segments. The adults 

 of Grenierella and Anasolen also conform in many characters (haired base to radius, 

 slender fore tarsus, bare katepisternum, haired ventral plate, minute claw-tooth in 

 female, unarmed or almost unarmed cibarium) but differ as follows : pleural 

 membrane bare in Grenierella (usually but not invariably haired in Anasolen), male 

 styles longer than coxites in Grenierella, scutum of female with definite pattern, the 

 paraprocts enlarged and the gonapophyses somewhat rounded in Grenierella. 



There are also some resemblances between Anasolen and certain other Neotropical 

 segregates in particular characters : the pointed subtriangular form of the female 

 gonapophyses is not unlike that found in subgenus Notolepria Enderlein and the 

 larval postgenal cleft and the black-tipped pupal gill filaments resemble to some 

 extent those of certain species of the New World subgenus Hearlea Vargas, Martinez 

 Palacios & Diaz Najera, but both Notolepria and Hearlea have the basal section of 

 the radius bare and differ by so many other major characters that it is unlikely that 

 there is close phyletic relationship between these subgenera and Anasolen. 



Within the African area there is little doubt that Anasolen is closely related to the 

 subgenera Freemanellum and Xenosimulium, the three subgenera apparently forming 

 a natural monophyletic group. In common they share the following characters : 

 basal section of radius haired, scutum without strong pattern, cibarium unarmed, 



