SIMULIIDAE OF AFRICA 95 



cephalic fans normal. Hypostomium with usual nine apical teeth, these short and blunt ; 3-6 

 setae in each hypostomial row, rows divergent behind from lateral margins of hypostomium. 

 Head-spots positive, usually very distinct and not lost in general pigmentation. Postgenal cleft 

 large, much longer than postgenal bridge, broadly and bluntly sagittate or subcordate. 

 Mandible normal, first three comb-teeth evenly decreasing, two serrations. Antenna short, with 

 four segments. Thoracic cuticle bare. Abdominal cuticle appearing bare but posterodorsally 

 with a few very minute deeply trifid setae. Abdominal shape normal. Ventral papillae absent. 

 Accessory sclerites absent. Rectal scales absent. Rectal gills without secondary lobules. 

 Posterior circlet with about 90-120 rows of 17-30 hooks. 



Distribution. Confined to the Palaearctic Region, and well represented in the 

 Mediterranean area and the Middle East. The distribution includes the British 

 Isles, Japan, Iran and West Pakistan but excludes Iceland ; the range may overlap 

 the fringes of the Oriental Region in Kashmir and West Pakistan proper. North 

 African distribution is shown on Map 9. 



Discussion. Wilhelmia forms an isolated subgenus in the Palaearctic Simidium 

 fauna having little or no apparent affinity with any other segregate in the region. 

 The formation of the pupal gill, the unique type of male hypopygium, the enlarged 

 claws and slender elongate gonapophyses of the female, all set the group apart from 

 the rest of the Palaearctic fauna ; on the other hand some of these characters 

 together with the characters of the larvae indicate almost certain phyletic affinity 

 with the endemic Ethiopian subgenera Metomphalus and Edwardsellum. The three 

 segregates taken together seem to form a natural group of subgenera within Simidium 

 having the following characters in common : Basal section of radius haired ; 

 styles of male genitalia small in relation to large coxites ; body of ventral plate 

 typically subtriangular with divergent basal arms ; scutum of female with at least 

 a trace of a lyrate dark mark (resembling Text-fig. 72) ; no trace of sclerotized 

 seventh sternite on female abdomen ; gonapophyses of female terminalia drawn out 

 into thin pointed processes, often curled ; cocoon with neck ; pupal gill composed 

 of large thin-walled basal arms with stout tubular filaments arising between them ; 

 dorsum of pupal abdomen without spine-combs ; postgenal cleft of larval head 

 large ; larval hypostomium with short blunt teeth and the rows of hypostomial 

 setae diverging posteriorly from the margin of the hypostomium ; larval antenna 

 about equal in length to stem of cephalic fan ; larval abdomen without ventral 

 papillae ; typically fast water forms with mammalophilic females. 



Stone (1963) placed the names Edwardsellum and Metomphalus as synonyms of 

 Wilhelmia, but it is here considered preferable to treat the three as closely related 

 but separate subgenera. Further discussion of the reasons for this is given under 

 Edwardselhim. 



The subgenus Wilhelmia forms a predominant component in the Simulium fauna 

 of the Mediterranean basin and its islands ; on the African continent it ranges from 

 Morocco to Tunisia. Two species, canariense and pseudequinum, that belong in the 

 subgenus have been described from the Canary Islands by Seguy (1921) : the 

 descriptions are of adults only and the identity of these species is uncertain, but it is 

 likely that at least one of the names applies to (and has priority over) mediterraneum 

 Puri. Adequate recognition of species in the subgenus Wilhelmia requires the pupal 



