Silba macrogonite
Description: Male. Head: Eyes bare. Frons sub-shining black, dulled by microsculpture.
Frontal and interfrontal setulae 0.25× length of orbital setae. Lunule,
ground colour orange-brown, viewed from above covered in a relatively dense
silver
pollinosity which extends onto parafacials and lateral margins of face. Antennae
black; postpedicel with a small orange area at extreme medial base, length
to depth ratio 3.0:1. Arista plumose, ratio of plumosity at maximum extent to depth
of postpedicel 1:1. Anterior genal setulae in a single row of four along mouth
margin.
Thorax: Scutum shining blue-black. Anepisternum with two anterior setae and
three posterior setae. Katepisternum with two setae located near dorsal margin,
anterior slightly shorter and weaker than posterior. Scutellum, on margin between
lateral and apical setae, with three setulae on left, four on right, two between apical setae. Calypteres entirely white with a uniform white fringe. Wings clear, veins
brownish, wing length 4.2 mm. Legs entirely black.Male terminalia: Epandrium in lateral view almost as wide as high, with numerous
setulae on posterior and ventral surfaces. Cerci relatively large, approx. 0.6×
height of epandrium, rather pointed posteriorly, bearing numerous setulae on ventral
and apical surfaces. Surstylus extending slightly beyond shell of epandrium as rounded
posterior ventral process, inner surface with row of six closely set prensisetae
along posterior margin. A single prensiseta and several strong setae situated ventral
to these, row of short setulae along medial part of ventral margin, posteroventral
lobe bearing a few stiff setae. A pair of stiff setulae situated centrally below base
of cerci. Pregonites greatly enlarged at apex to form two distinct lobes of almost
equal size, posterior lobe setulose. Phallus very simple open U-shaped.