Description. Male: Head. Eyes bare. Frons matt black with light grey dusting, parallel sided, half width of eye.
Frontal setulae short, approximately one fifth length of orbital setae. Interfrontal setulae equally short and sparse.
Orbital plate subshining black, bare apart from orbital setae which are slightly shorter than the ocellar setae.
Lunule, face and parafacials matt black with only slight silver dusting. Lunule bearing approximately eight short
setulae. Genal setae short, anteriorly forming a single row of five along the oral margin, becoming stronger posteriorly,
the basal of the five being the strongest on genae. Antennae entirelly black, 1st flagellomere 2.5 times longer
than deep. Arista short plumed for a Silba species, with maximum extent of plumosity equal to half depth of the 1st
flagellomere. Palpus entirelly black.
Thorax. Thoracic dorsum and sclerites subshining black, covered with light grey dusting, setulae covering dorsum
very short, at maximum 0.25 length of orbital seta. Anepisternum with three strong setae anteriorly, three posteriorly.
Other setulae on the sclerite rather sparse and short, no more than 0.25 of the setae. One propleural and one
stigmatical seta. Prosternum with three weak seta on each side. Dorsal margin of katepisternum with one strong
seta, a much shorter and finer seta situated anterior to it (in some paratypes this anterior seta is practically indistinguishable
from other setulae on the sclerite), remainder of katepisternum bare apart from a scattering of five to
seven short setulae on anterodorsal portion. Scutellar dorsum subshining, lightly grey dusted, slightly more brassy
in colour than thoracic dorsum, with three short marginal setulae between lateral and apical setae, two tiny setulae
present on the margin between apical setae. No setulae present anterior to lateral setae. Calypteres pale with pale
margins and a short whitish fringe. Wings hyaline. Wing length 3.7 – 3.8mm. Legs entirelly black.
Male terminalia (Figs. 1–3). Epandrium in ventral view slightly longer than wide with semi circular excavation
anterodorsally, long setulae scattered posteroventrally. Cerci extending posteriorly, about half height of epandrium
(Fig. 1), not sclerotised, bearing short setulae on margins and apex. Surstyli not projecting beyond shell of
epandrium although the upper surstylar teeth are just visible posteriorly. In ventral view surstyli slightly visible
ventrally, their margins bearing a row of brownish setulae with the posterior 5 are strong and spine-like. A row of 7
relatively large sharp black teeth present on posterior lobe forming a curved row on inner surface of the surstyli,
gradually decreasing in size ventrally. A pair of short setulae present just below bases of cerci. Aedeagus distinctive
(Fig. 3), a rather simple U-shape with two basal side arms, these gradually narrowing and pointed apically.
Female. Similar to male except with overall shorter setulae on the integument and wider frons 0.25 the width
of an eye.
Female terminalia ( Fig 4). Aculeus gradually narrows towards apex, Apical segment dorsoventrally flattened,
diamond shaped, basally embedded into the aculeus, with a pair of downward pointing short lateral setulae and two
or three very short setulae lying anterior to these. Aculeus and apical segment noticeably golden-brown.
Description of third stage larva (N=2). Length 4.5-5mm; maximum width 0.68-0.83mm; maximum height
0.83-0.91mm. Truncate posteriorly, tapered anteriorly; dirty white except for black margins of posterior spiracular
plates, red-brown margins of posterior spiracles and black sclerotised cephalopharyngeal skeleton; anterior spiracles
consisting of eight respiratory bulbs arranged in a fan; posterior spiracular plates borne on short (0.05-
0.06mm) projections and sited on upper apical margin of anal segment; spiracular plates oval, separated by about
two times the width of the spiracular plate; spiracular openings straight, about equidistant from each other and ger than wide (0.03mm long x 0.01mm); cuticular scar black and on inner, upper margin of plate; four groups of 3-
4, short, interspiracular setae present; oral lobes of pseudocephalon coated in cirri; integument without vestiture
except the following: anterior margin of prothorax circumvented by numerous, short, straight or curved bars of
upright microspicules generally orientated transversely across the segment; locomotory spicules on the anterior and
posterior segmental boundaries of all abdominal segments consisting of 7 transverse rows of even sized spicules
with 4 rows on the posterior margin and 3 on the anterior margin of each segment; mesothorax and metathorax
without spicules or vestiture; anus surrounded by short spicules anteriorly and longer spicules posteriorly, laterally
without surrounding spicules. Cephalopharyngeal skeleton (Fig. 5) length 0.36mm; mandible with rectangular
base, a curved apical hook and an oval-shaped dental sclerite sclerotised black; intermediate sclerite sclerotised
black, bar-shaped; vertical plate and dorsal cornu sclerotised; ventral cornu brown, not as sclerotised; cibarial