SIMULIIDAE OF AFRICA 99 



The undeveloped neck to the cocoon, also atypical for Metomphalus, may be a 

 character associated with the fact that the species breeds often in rather slow waters. 



Included taxa : Simulium {Metomphalus) albivirgulatum Wanson & Henrard. 



bovis-group. Small species, wing length 1-6-2-3 rnm. o" scutum without pattern or with 

 very bold conspicuous pattern of black and pale silver-grey, as in Text-fig. 76 or with the centre 

 vitta merging with lateral black vittae. o* ventral plate of varied form, usually body of plate 

 subtriangular with divergent basal arms, or broadly transverse with parallel basal arms (Text- 

 fig. 115) ; coxite often produced as a narrow elongate process beyond base of style. $ cibarium 

 unarmed. Pupal gill with stout primary filaments and fine slender secondaries, without basal 

 arms. Pupal abdomen unusual, lacking hooks or showing only one minute inconspicuous hook- 

 let each side on segment 5. Cocoon with neck. Postgenal cleft very large and rounded. 

 Hypostomium with normal teeth (Text-fig. 280), 4-5 setae in each hypostomial row. Larval 

 thoracic cuticle bare, abdominal cuticle with minute flattened truncate • scales posterodorsally 

 and abdominal shape as in Text-fig. 228. 



This group contains species that are most uniform in the immature stages but 

 more diverse in the characters of the male and female terminalia, particularly 

 because of the inclusion of S. wellmanni in the group. This species differs from all 

 other African Simulium s.l. in possessing multiple spinules on the style of the $ 

 genitalia (Text-fig. 153) and from other members of the bovis-group by having the 

 median sclerite deeply cleft and the apical prolongation of the coxite equal in length 

 to the style : characters of the female, larva and pupa of wellmanni, however, 

 undoubtedly indicate close affinity of this species with bovis and its immediate allies 

 (for description of the larva of wellmanni see Grenier et al. (1961 : 1139)). Until 

 recently S. wellmanni also appeared unique on account of the long straight very 

 slender and backwardly-directed gonapophyses of the female terminalia (Text-fig. 

 160) but S. janzi has been shown to have similar gonapophyses (figured by Marini de 

 Araujo Abreu (1961 : 84)) ; the male of S. janzi has a complex ventral plate 

 essentially of transverse shape like that of wellmanni, but has only one apical spinule 

 on the style and a much shorter coxite process, thus providing an aggregate of 

 characters intermediate between those of wellmanni and those of bovis. The form 

 of the pupal gill of janzi also falls between that of wellmanni and that of bovis, and 

 supports the inclusion of wellmanni in the bovis-group. 



The larvae of the bovis-group species are small and usually very pale, with little 

 body mottling and with the head capsule often creamy white with almost no pig- 

 mentation ; the membranous area of the large rounded postgenal cleft tends to be 

 inconspicuous against the pale head colour (in contrast to the larvae of the medusae- 

 forme-group in which pigmentation is well marked and the postgenal cleft conspic- 

 uous). Body form in the larvae tends to resemble that occurring in the subgenus 

 Pomeroyellum, but without ventral papillae (Text-fig. 228) ; the scales of the abdomen 

 are minute and inconspicuous, so that the larvae appear bare at first glance, unlike 

 the very large abdominal scales found in the albivir gulatum-gr oup of Metomphalus 

 or the cervicornutum-group of Pomeroyellum (Text-fig. 224) that are immediately 

 obvious. 1 



1 McCrae (personal communication) has now obtained bovis-group larvae from Ethiopia, that appear 

 to be those of S. fragai or a very closely related new species, in which abdominal scaling is obvious on 

 much of the dorsum of the abdomen and around the sides of the terminal segments. 



