ON THE BRITISH SPECIES OF SIMULIUM. 41 



12. Simulium subexcisum, sp. n. (figs. 1, 2, 3, 6). 



Lengthy 2-2-3 mm. 



Male. — Thorax velvet-black, with yellowish, not deep golden pubescence (in 

 the two specimens examined the mesonotum was much denuded) ; scutellum with 

 yellowish hair which is longer than usual. Pleurae bare. Abdomen velvet-black, hair 

 on the basal segment yellowish. Genitalia (two mounts compared : fig. 1, n) : side-pieces 

 large ; claspers roundish in section, tapering towards the tip, somewhat curv^ed, with 

 a single short spine at the tip ; adminiculum as in the figure. Legs uniformly blackish, 

 with coarse yellowish pubescence, except on the tarsi ; front femora and hind femora 

 and tibiae with long dark hair, which is denser on the hind tibiae than in any other 

 British species except S. hirtipes (one of the specimens is denuded). Front tarsi 

 thin, cylindrical ; hind metatarsi distinctly thickened, though not so much so as in 

 S. latipes. Second hind tarsal joint (fig. 6, c) with only an irregular emargination 

 at the base, not a definite excision as in the eleven preceding species. Wings with 

 normal venation. Halteres blackish. 



Fig. 6. Tip of metatarsus and whole of second tarsal joint of : 

 a, Simulium equinum, ; b, S. hirtipes ; c, S. subexcisum ; 



X 60. 



Female. — Head clothed with coarse yellowish pubescence ; face yellowish grey ; 

 frons greyish below, darker and slightly shining above, narrower than in the other 

 species. Antennae all black. Thorax dull blackish-grey, the mesonotum densely 

 clothed with coarse pubescence, which is sometimes uniformly yellowish, sometimes 

 however showing three broad longitudinal stripes of dark brown.* Abdomen dark, 

 densely clothed with coarse yellowish pubescence. Legs (fig. 3, e, front tarsus) 

 entirely dark brownish-black ; less hairy than in the male ; hind metatarsi not 

 thickened ; second hind tarsal joint as in the male ; claws (fig. 2, /) much 

 resembling those of >S. latipes and its allies. Halteres yellow. 



Type (J in the Cambridge Museum, from Crowborough, Sussex, 9.iv.l904: (J.). 



Time of appearance. — April to June. 



Distribution. — Though widely distributed, apparently a rare species, as I have not 

 seen more than four specimens from any one locality. England : New Forest 

 (D. Sharp, Y .) ; Crowborough, Sussex (J .) ; Harrow Weald, Mddlesex (E) ; Tarrington, 

 Hereford (Y.). Scotland: Aviemore, Dunachton and Nethy Bridge (G., Y .) \ 

 Nairn (Y.) ; The Mound, Sutherland (Y.). 



Habits. — Nothing recorded. 



* It is possible that these two forms of the female may represent distinct species, but 

 there are no structural differences. 



