Silba vanemdeni McAlpine

Both sexes of Silba vanemdem can usually be distinguished from atratula (Walker) by the presence of a single, strong, clearly outstanding vibnssa-like bristle in the middle of the series of oral setulae (several much weaker setulae in this position m atratula); m addition, it is smaller in size and has paler brownish wmgs. The short male aedeagus with a Y-shaped process at base (fig. 20, McAlpine 1956) is the best means for positive identification (aedeagus long and slender with no basal process in atratula. Figs. 30-32).

Comparison of the specimens which I earlier identified as atratula McAlpine 1956, following van Emden's identification) and additional specimens studied since then, with the holotype of atratula Walker (see above) showed that they belong to a different but related species. This opportunity is taken to name it m honour of the late Dr. F van Emden, formerly of the British Museum (Nat Hist.). Description. A full description of the male with figures of the genitalia was provided in my 1956 paper (loc. cit). Female. Differing from male as follows Somewhat smaller and distinctly more shmmg on mesonotum and abdomen Frons much broader, with sides almost parallel; length from anterior ocellus to lunule equal to width at lunule (10 0 10.0), weakly shining brownish black Wings paler with more yellowish veins Calyptrae white with pale yellowish margins and fringes Abdomen much longer in relation to width Ovipositor (Figs 35, 36) widest m middle, gradually tapered to apex Apical segment about 2lh times as long as wide, sides gently converging to bluntly angular apex, subapical ventral hairs slightly longer than subbasal dorsal hairs