28 R. W. CROSSKEY 



anchor-like or grapnel-like hooklets on each side of terminal segments. Cocoon well 

 formed, with discrete definite shape and usually a well defined anterior rim. Larval 

 head with incomplete postgenal bridge, a long postgenal cleft extending forwards to 

 reach the hypostomium. 



The type-species of Cnephia has fades A delimited above, and so also does 

 lapponica Enderlein, the type-species of Astega Enderlein, which Rubzov (1959- 

 1964) places in his lapponica-group of Cnephia. Hence the name Cnephia strictly 

 applies to this segregate and Astega is a synonym of Cnephia. 



Forms with the second facies B delimited above, it is here considered, cannot be 

 assigned to the same genus or subgenus as those with facies A, and therefore cannot 

 be placed in Cnephia : there is no available genus-group name already published 

 that can be applied to the group, and the new genus Metacnephia is therefore here 

 erected for them, with Cnephia saileri Stone fixed as type-species (this species has 

 been chosen as type because more material is available than for the other included 

 species). The new genus includes all the taxa assigned to the pallipes-group by 

 Rubzov and six of the species listed in subgenus Cnephia by Stone (1965) : a 

 complete enumeration of the assigned species, establishing the new combinations 

 that arise, is given later. 



Metacnephia has a suite of characters intermediate between those of Prosimulium 

 s.l. and those of Simulium s.l., and is therefore an annectant genus between typical 

 forms of Prosimuliini and Simuliini, tending to bridge such character break — at 

 best a rather weakly defined one — that exists between these tribes. Some of the 

 characters of Metacnephia are almost unique to the genus or of very rare occurrence 

 elsewhere among world Simuliidae : the larval head-capsule is broadly membranous 

 in the mid- ventral line without a sclerotized postgenal bridge interposed between the 

 usual cleft and the hypostomium (i.e. the postgenal cleft reaches forward on the head 

 capsule to abut broadly on to the base of the hypostomium, thus completely separat- 

 ing the sclerotized genal regions of the two sides of the head as shown in Text-fig. 

 36) ; such a head never occurs in the larvae of Prosimuliini (in which the floor of the 

 head-capsule is fully sclerotized for a long distance behind the hypostomium), but 

 there are a few forms of Simuliini in which the cleft reaches forward to the hypo- 

 stomium (in the subgenera Byssodon and Simulium s. str. of Simulium) — hence the 

 larval head suggests closer affinity with Simuliini than with Prosimuliini. No clear 

 evidence of affinity, however, is suggested by the extraordinary ramified (usually 

 biramous anchor-like or triramous grapnel-like) hooklets at the end of the pupal 

 abdomen in Metacnephia, for these are of sporadic occurrence elsewhere, e.g. in at 

 least some species of Gigantodax Enderlein (Prosimuliini) and Austrosimulium 

 Tonnoir (Simuliini) , and in the type-species of the anomalous (at present monotypic) 

 segregates Greniera Doby & David from western Europe and Par austrosimulium 

 Wygodzinsky & Coscaron from Tierra del Fuego. The reduced terminal tubercles of 

 the pupal abdomen and the well formed cocoon are of the type found in Simuliini. 



The adult stage of Metacnephia resembles Prosimuliini because of the lack of 

 pedisulcus and presence of a basal cell in the wing, but the nature of the mesepi- 

 sternal sulcus and katepisternum (which I believe provides a fundamental distinction 



