SIMULIIDAE OF AFRICA 101 



the hind basitarsus of the male distinctly dilated : in the albivirgulatum-gvoup and 

 the bovis-group the male hind basitarsus is always slender and parallel-sided. 



Included taxa. Simulium (M etomphalus) africanum Gibbins ; S.(M.) cavum 

 Gibbins ; S.(M.) colasbelcouri Grenier & Ovazza ; S.(M.) futaense Garms & Post ; 

 S.[M.) hargreavesi Gibbins ; S.{M.) letabum de Meillon ; S.(M.) medusaeforme 

 Pomeroy ; S.(M.) natalense de Meillon ; S.(M.) ruandae Fain ; S.[M.) taylori 

 Gibbins ; S.(M.) touffeum Gibbins ; S.(M.) vorax Pomeroy ; S.(M.) zombaense 

 Freeman & de Meillon. 



In addition the nomenclaturally unavailable form name angolensis has been 

 applied by Marini de Araujo Abreu (1961) to a taxon of this group. 



Ungrouped species : Simulium gyas de Meillon. 



The species Simulium gyas de Meillon from Madagascar may belong in the sub- 

 genus Metomphalus, but at present it is known only from the larval and pupal stages 

 and there is insufficient evidence for definite assignment to this subgenus. The 

 cocoon in this species is reduced, covering only the pupal abdomen and postero- 

 dorsal part of the thorax, but the abdominal onchotaxy of the pupa conforms with 

 that of Metomphalus : the pupal gill (Text-fig. 208) has six stiff branches arising in 

 pairs, unlike any other African species, but suggesting some possible relationship 

 with 5. hargreavesi Gibbins. If a form such as hargreavesi lost the fine secondary 

 filaments of the gill so that only the main primary arms were retained it would 

 resemble gyas in gill form, so that the six branches existing in gyas could possibly be 

 homologous with the primary gill filaments in hargreavesi and its allies. 



This suggestion of possible affinity with hargreavesi is supported by the larval 

 characters of gyas which have been described and figured by Grenier and Doucet 

 (1949) under the name Simulium sp. M6 ; the form of the postgenal cleft, the man- 

 dible, the cuticular spines of the abdomen, and the hypostomium and its setae all 

 conform with the larval characters of the medusaeforme-group of Metomphalus. 

 Simulium gyas therefore, on the basis of its known stages, shows most affinity with 

 subgenus Metomphalus and could tentatively be assigned to this subgenus pending 

 discovery of the adult stage. 



Subgenus EDWARDSELLUM Enderlein 



Edwardsellum Enderlein, 1921 : 199. Type-species : Simulium damnosum Theobald, 1903, by 

 original designation. 



Diagnosis, o"? : Basal section of radius haired. Pleural membrane bare. Katepisternum 

 bare. Fore tarsus greatly dilated, fore basitarsis 3-6-4-2 times as long as its greatest breadth, 

 with dorsal hair crest. $: cibarium unarmed. Tarsal claws with basal tooth, sometimes small. 

 Scutum black with bluish grey bloom and very inconspicuous pattern of three fine dark longi- 

 tudinal lines. Abdomen densely silver-scaled on segment 2 and with lateral and ventral tufts of 

 silvery white scales on segments 2-5, dorsum of segments 5-9 shining black with only sparse 

 erect hairs. Seventh sternite undeveloped. Gonapophyses attenuate, usually curled acumin- 

 ate. Paraprocts normal. Spermatheca with internal hairs, surface smooth. <J : scutum with 

 bold black and silvery grey pattern. Genitalia with small tapering styles shorter than coxite ; 



