SIMULIIDAE OF AFRICA 21 



considers to be the only Nearctic species assignable to Helodon, and some North 

 American Prosimulium s. str. On a world basis I can see no justification for treating 

 Helodon as a valid subgenus, and regard it as forming at most a species-group within 

 Prosimulium s. str. equivalent to the hirtipes-gvoup as recognized by Rubzov : I 

 therefore place Helodon as a synonym of Prosimulium s. str. 



Likewise the segregate Urosimulium, described by Contini (1963) as a full genus, I 

 cannot see as more than a moderately distinctive species-group within Prosimulium 

 s. str., and therefore sink the name in synonymy ; Contini cited as diagnostic 

 characters the elongation of the cerci of the female, the triangular shape of the male 

 ventral plate and the bilobate character of the male style, but no differences in the 

 immature stages from Prosimulium s. str. More recently Contini (1966) has been 

 obliged, because of the elongate female cerci and bilobate style, to place in Uro- 

 simulium a second species in which the male ventral plate is quite another shape. 

 The indentation of the style and attenuation of the cerci are matters of degree, and 

 in the absence of clear-cut adult features or of any characters from the early stages 

 for separating Urosimulium it is impossible to accept this segregate as valid at 

 subgeneric level if named segregates are to be adequately balanced : like Helodon, 

 I consider it best to treat Urosimulium as at most a species-group within the sub- 

 genus Prosimulium s. str., and to sink the former name as a synonym. 



The other names cited in synonymy with Prosimulium s. str. (see above) have been 

 discussed by Stone (1963), and no further comment on these is required. 



Rubzov ( 1 959-1 964) recognizes three species-groups in the Palaearctic fauna of 

 Prosimulium s. str., but these have not been considered in detail for purposes of the 

 present paper as only the one species, record cited above, is known from Africa ; 

 this belongs in Rubzov's hirtipes-group, which is therefore the only group of Pro- 

 simulium s. str. found in the African area. 



Included taxa. All Nearctic species placed in the genus Prosimidium in the cata- 

 logue of Stone (1965), and all Palaearctic species placed in Prosimulium and Helodon 

 in the monograph of Rubzov (1959-1964). In addition the following recently 

 described Palaearctic species that are not covered in Rubzov (op. cit.) : albense 

 Rivosecchi, 1961 ; aculeatum Rivosecchi, 1963 (= stefanii Contini, 1963) ; 

 goidanichi Rubzov, 1964 ; juccii Contini, 1966. 



The assignment of all these species to subgenus Prosimidium s. str. in an enlarged 

 concept for the genus does not involve new combinations, except for Urosimulium 

 juccii Contini for which the new assignment is Prosimidium (Prosimidium) juccii 

 (Contini) comb. n. 



Subgenus PROCNEPHIA sgen. n. 



Type-species : Prosimidium rhodesianum Crosskey, 1968. 



Diagnosis. Costa with hair-like macrotrichia only, some macrotrichia in male sometimes 

 thickened and differentiated from hairs but not fully spiniform. Vein Rs not forked, though 

 sometimes slightly expanded apically with suggestion of last remnant of forking. Calcipala 

 absent or very rudimentary (Text-fig. 22). Claws of female with moderately developed to large 



