Silba bisulcata
Length of the body, 4 mm. ; of the wing, 4*2 mm.
Frons proportionally narrow, a little less than twice as long as broad ; it is duUish
black, with sericeous reflexions and with shining black vertical plates ; in front of
the ocellar plate there is a rounded depression, from the sides of which emerge
two rather deep furrows, which converge towards the antennae, ending separately
at the upper border of the lunula. Antennae wanting in the type. Face black,
greyish-dusted, with rather shining antennal grooves ; cheeks linear ; jowls narrow ;
palpi and proboscis black ; chaetotaxy normal. Thorax shining black, with no distinct
bluish reflexions ; chaetotaxy normal ; two equally strong sternopleural bristles.
Scutellum aeneous and faintly dusted, with numerous bristly hairs between the
usual bristles. Squamuiae yellow, with pale yellowish cilia ; halteres black.
Abdomen coloured and shining like the mesonotum, with black hairs and short
black bristles on the sides ; ventral membrane broad and reddish, ventral plates
shining black ; ovipositor short, as long as the last two abdominal segments together.
Legs entirely black ; middle femora with rather short but complete ciliation on
hind side. Wings yellowish, deeper yellow at base and on fore half ; veins yellowish,
but the costa appearing darker on account of its short black ciliation ; second costal
cell but little widened outwardly ; terminal portions of third and fourth veins parallel,
not diverging ; small cross- vein before the middle of the discoidal cell ; hind crossvein
straight, about twice as long as its distance from the end of the fifth vein ; sixth
veiQ with spurious continuation.
Type female, a single specimen