Silba adipata 1956
As with most Silba species identification is best confirmed by examination of the male genitalia . The aedeagus is J-shaped, relatively stout and two segmented, the apical portion is long and almost straight whilst the thicker basal portion usually bears a varying number of tiny spinules (this can be difficult to see under some light conditions). The surstyli ventrally bear a row of 5 - 6 blunt, black teeth on their inner surface, the most ventral of these being relativey large and out of line with the rest, in lateral view it can usually be seen projecting from the shell of the epandrium. There is usually one outstanding strong setae at the ventral corner of the epandrium which is twice as long as the other setulae. In ventral view the inner margin of the surstyli has a seies of ridges which result in a characteristic invaginated outline of the inner margin
Silba adipata - Species description (McAlpine 1956 p524)
A medium sized species somewhat smaller than S. plumossisima (Bezzi). The base of the antennae, the lunule and usually the adjoining areas of the frons brownish or brownish–orange. Thorax, including the scutellum, and the abdomen appearing greasy-shiny ; notum relatively densely whitish pollinose with distinct aeneous green reflections in mature specimens. Scutellum often rather strikingly greenish as in Lonchaea scutellaris Rondani
Male – Head about one fifth wider than high. Frons fully one-fourth as wide as head (2.8 : 11.66); about four-fifths as wide as high (2.8 : 3.5); very little narrowed anteriorly , with a rather conspicuous but poorly defined transverse depression immediately in front of the anterior ocellus; distinctly silky-shiny but also uniformly lightly dusted with whitish pollen which irideces under certain lights; each side with some 12 to 19 inferior orbital setulae, no hairs visible above orbital bristle in side view. Parafacials almost linear, silvery pollinose. Oral setulae uniserial , with an outstanding vibrissa-like bristle among them. Lunule densely silvery pollinose over an orange-brown ground colour, bearing 10 setulae of about the same length as the interfrontal setulae. Third antennal segment about 2 and five eighths as long as wide (3.5 : 1.3), always extensively orange to orange brown at the base inside. Plumosity of arista slightly wider than the width of the third antennal segment, basal one third of the arista orange – yellow.
Mesonotum uniformly rather heavily dusted with whitish pollen; greasy shiny; bronzy-green to aeneous-blue in colour. The usual bristles including two dorsocentrals strong whilst the setulae are short and depressed. Scutelum rather contrasting shining bronzy green in most specimens, always heavily pollinose; with four or five lateral setulae on each side between the lateral and apical scutellar bristles and a weaker pair between the apical bristles. Pleurae entirelly pollinose, concolourous with mesonotum. Sternopleuron often with a weak setula behind the posterior sternopleural bristle. Prosternum with three or four hairs on each side anteriorly.
Legs and tarsi brownish black, preapical dorsal bristles of the mid and hind tibiae hardly distinguishable from the hairs, those of the front tibiae indistinguishable
Wings pale hyaline, veins pale yellowish. Calypterae white or pale yellow with concolourous fringes.
Abdomen, like the mesonotum, entirelly rather densely pollinose and with the same greasy, aeneous colour. Genitalia similar to those of S. filifera (Bezzi) but aedeagus much shorter; in addition the surstyli much more distinctly ridged anteriorly and bearing a lesser number of stout teeth posteriorly.
Female – frons wider than high (3.66 : 3.1) about one third of head width (3.66 : 11.0); transverse depression in front of orbital bristles and the anterior ocellus more clearly defined than in the male, forming an inverted W; with thirteen inferior orbital setulae in the allotype. The aristal plumosity narrower than in the male, i.e. slightly narrower than the third antennal segment. The lowermost two or three oral setulae stronger than the others.
The apical one third of the ovipositor tapering evenly to a sharp point; the apical segment with several very short hairs on each side, the longest of these being hardly as long as the width of the ovipositor opposite the base of the hair.