Silba japonica
With the basal plate of the surstylus
projecting from the epandrium shell as a rounded
process bearing the prensisetae and a strong seta on the
genae this species shows affinities with the Silba virescens
Macquart, 1851 group of species
Description. Male. Head: Eyes bare. Frons half width
of eye, widening slightly from level of ocellar triangle
to antennal bases, dull black, frontal and interfrontal
setulae short, less than one fifth length of orbital setae.
Orbital plates shining black and bare apart from orbital
seta. Lunule bearing approximately eight setulae. Face
and parafacial slightly greyish black. A single row of 6
or 7 anterior genal setulae along mouth margin, becoming
progressively longer and stronger basally, basal one
very strong and long, seta-like and clearly strongest
setula on gena. Antenna entirely black, 1st flagellomere
long, nearly 3 times longer than deep, arista short
haired, maximum width of arista plus hairing approximately
half depth of 1st flagellomere.
Thoracic disc subshining black, covered with short
setulae of no more than one-third length of orbital seta.
Pleura subshining black. Anepisternum with 3 strong
setae anteriorly and 3 posteriorly. Katepisternum with
two strong seta near dorsal margin, posterior slightly
stronger than anterior, otherwise bare apart from 7–8
short setulae along anterior margin. Proepimeron with
one seta, one slightly weaker stigmatical seta. Scutellar
disc shining, margin between lateral and apical setae
with 4 setulae, 5 very short setulae between apical setae.
Calypteres greyish with yellowish fringe. Legs entirely
dark. Wings clear with dark veins, wing length 4.0 mm.
Male genitalia (Figs 8–9): Epandrium in lateral view
wider than high, ventrally with a rounded process at
base of cercus, bearing row of longer setulae along posterior
margin and scattered setulae on posterior surface.
Cercus descending posteriorly, almost as long as epandrium
is high, bearing rather coarse setulae apically.
Surstylus projecting slightly posteriorly beyond shell
of epandrium, basal plate prominent, bearing 5 prensisetae,
posterior four long, strong and curved, lower
thinner and more seta-like. In ventral view one moderately
strong seta located beneath base of each cercus.
Ventral margin of surstylus bearing regular row of
strong setae, inner surface with four or five small lateral
ridges. Phallus, two-segmented a simple J-shape, where
the apical portion meets basal slightly serrated, base of
phallus with very distinctive pair of large claw-like internal
basal processes.