322 F. W. EDWARDS. 



Subgenus Ecculex, Felt. 



Adult.— As in Ochlerotatns. but the male palpi are usually no longer than the 

 proboscis ; the vertex and the scutellum in many species are covered with fiat 

 scales ; lower mesepimeral hairs are usually absent ; the male hypopygium has no 

 distinct claspettes, these being represented by hairy basal lobes ; while, on the other 

 hand, the claspers are highly modified in most species, and even in the simple forms 

 are distinguished by having the spine inserted before the tip. The aedoeagus is 

 quite different from that of Ochlerotatns, but almost identical with that of Aedes. 

 The hind claws are usually simple. 



Larva.— Vxz.ct\c?i\\y as in Ochlerotatns, but the pecten usually has detached teeth 

 outwardly, which in Ochlerotatns is rarely the case, and the siphonal tuft is usually 

 distinctly beyond the middle. 



In E. vexans the frontal hairs are situated one in front of the other, as in Ochlcro- 

 tatus, but in the rather numerous Ethiopian species of which the larvae are known 

 the anterior pair is placed outside the posterior, as in Culex and Aedes (s. str.). 



It is only with reluctance, in deference to the opinion of Dyar, that I recognise 

 this as a distinct subgenus, as it is almost impossible to define apart from the characters 

 of the male hypopygium. However, there is no doubt that it is a natural group, 

 representing a distinct line of evolution in which the clasper has undergone 

 specialisation instead of the claspette. The separation is confirmed by present-day 

 distribution, the species being numerous in the Oriental and Ethiopian regions, only 

 a single one extending into the Palaearctic and Nearctic, while none are found in 

 the Neotropical, and only one or two in north Australia. 



33. Aedes (Ecculex) vexans (Mg.). 



Culex vexans, Meigen, Syst. Beschr. vi, p. 241 (1830). 



(?) Culex parvus, Macquart, Suites a Buffon, i, p. 36 (1834). 



Culex articidatus. Rondani, Bull. Soc. Ent. Ital. iv, p. 30 (1872). 



Cidex malariae. Grassi, Atti Ace. Lincei, vii, p. 168 (1898) ; No6, Bull. Soc. Ent. 

 Ital. xxxi, p. 244 (1899). 



(?) Culex arahiensis, Patton (adult, not larva), J. Bombay Nat. Hist. Soc. xvi, 

 p. 633 (1905). 



Apart from the characters of the male hypopygium and the somewhat shorter 

 male palpi, this species is not easy to distinguish from the annulipes group of the 

 subgenus Ochlcrotatus, especially small specimens of A. macnlatus. The structural 

 and scale characters are the same, except that the hind claws are often (not always) 

 simple ; in both the lower mesepimeral bristles are absent. We have therefore, in 

 the case of the female, to rely mainly on coloration for the determination of this species, 

 the most constant feature being the median emargination of the pale abdominal 

 bands. The white tarsal rings are always narrow, but rather variable ; in large 

 specimens they are sometimes not much narrower than those of the narrowest-banded 

 specimens of A . maculatus ; while in the other examples (generally small ones) 

 they are often so narrow as to be visible only under a lens. The head markings 

 (the uppermost of the flat scales at the sides of the head being black, the rest pale) 

 are of a type very rarely met with in Ochlerotatns, but common in Ecculex, Stegomyia 

 and Finlaya. E. vexans differs from the great majority of species of the subgenus 

 in having no flat scales either on the vertex or on the scutellum, its resemblance to 

 the subgenus Ochlerotatus being thus increased. 



Two varieties occur within the Palaearctic region : the typical form, in which 

 the abdomen has only the emarginate white bands on a dark ground ; and the 

 variety nipponii, Theobald, in which the abdominal segments have, in addition to 

 the bands, a median whitish patch. 



