Silba breviplumosa, Introduction & Fallén & Morge, 2007

Introduction, Iain, Fallén, Lonchaea & Morge, Setisquamalonchaea, 2007, New pecies of Lonchaeidae (Diptera: Schizophora) from Asia, Zootaxa 1631, pp. 1-32 : 17-18

Silba breviplumosa sp. nov.

Description. Holotype male: Head: Eyes bare. Frons just less than half eye width, almost parallel sided between ocellar triangle and bases of antennae, flat apart from some minute linear striations, with some light grey dusting, bearing very short frontal and interfrontal setulae which are not more than one fifth as long as orbital setae, longer setulae present on anterior margin above lunule. Orbital plate narrow and rather matt with fine microsculpture, bare apart from orbital setae. Lunule with orange brown ground colour, this coloration extending across the entire face and lower parafacials, centre of the face slightly metallic in some lights. A single row of six anterior genal setulae extending along mouth edge, basal setulae of this row the strongest on the genae but not markedly stronger than the others. Antennal flagellomere all black, two and a half times as long as deep, reaching over the mouth edge, apex rounded. Arista yellowish basally, plumosity at its maximum extent approximately half as wide as the depth of antennal flagellomere.

Thorax: disc and pleurae lightly dusted, setulae on disc short, only one third as long as orbital setae. Anepisternum with three long and strong anterior setae and three similar posterior setae. One propleural setae and one shorter and weaker stigmatical. Two strong setae on the katepisternum, posterior slightly longer and stronger than anterior, a few longer setulae half as long as anterior setae lying anterior to anterior setae, other shorter setulae also present on anterior part of this sclerite. Scutellum with lateral strong setae situated on the edge of the scutellar disc obviously dorsal to the level of the insertion of the apical setae, the lateral setae long, reaching back over the scutellum three quarters of the way along the length of the apical pair, margin with two short setulae between apical setae, six setulae between apical and lateral setae on one side four on the other, these in double rows with two upper setulae longer than the lower four. Squamae greyish with a dark fringe. Wing length 4.0mm. Legs black.

Male terminalia; Figs. 31–34. In lateral view epandrium one and a half times higher than wide, almost tear-shaped but with a slight excavation on the dorsal margin, posteroventrally with several rows of relatively long setulae these extending down the ventral margin, four or five situated posteriorly these relatively long and strong, three quarters length of the cerci. Cerci leaf-shaped, narrowed at base, half height of epandrium, apical half covered in short setulae. Surstyli projecting posteriorly as a rounded lobe, basal plate also visible, anteriorly also extending as a small rounded lobe. In ventral view lateral margins of surstyli with a fringe of short setulae, basal plate bearing five short, black teeth. One long, thin spine situated at the base of each cercus. Aedeagus with basal part deep, arising from this a single lower rounded process above which lie a pair of thin, straight, pointed processes.

Differential diagnosis; This species is similar to several other Malaysian Silba species with dark squamal fringes and dark legs, apart from the noticeable short plumosity on the arista this species is most easily separated by the distinctive features of the male terminalia.

TYPE MATERIAL: Holotype male. MALAYSIA: Cameron Highlands , 14.iv.1985, leg. D. K. McAlpine.

Only known from the holotype in the AMS.

Etymology. The specific epithet is derived from the relatively short plumosity on the arista.