Silba longidentata, Introduction & Fallén & Morge, 2007

Introduction, Iain, Fallén, Lonchaea & Morge, Setisquamalonchaea, 2007, New pecies of Lonchaeidae (Diptera: Schizophora) from Asia, Zootaxa 1631, pp. 1-32 : 23-25

Silba longidentata sp. nov.

Description: Holotype male: Head: Eyes bare. almost parallel sided widening only slightly dorsal to antennal bases, at narrowest point two thirds eye width, dull black with microsculpture, bearing short frontal and interfrontal setulae no more than one fifth the length of orbital setae, some longer setulae present along anterior margin. Orbital plates dulled by microsculpture, without setulae. Lunule with four setulae on each side, ground colour dull black but with slight silvering. Face subshining black, slightly silvered, parafacials slightly silvered. Anterior genal setulae in a single row of six along mouth margin, these slightly separated from other setulae on the genae, basal two anterior setae amongst the strongest on the genae although there is also a strong setae-like setulae on the anterior edge of the main group of setulae under eye. Antennal flagellomere entirelly black, two and three quarters as long as deep. Arista brownish basally, with plumosity at its maximum extent just less than depth of antennal flagellomere.

Thorax: Disc subshining black, almost entirely covered with fine dust, covered with setulae approximately one third as long as orbital setae. Pleurae dusted. Anepisternum with three strong anterior setae and three strong posterior setae. Katepisternum with two setulae, anterior one slightly weaker than posterior. One propleural and one weaker stigmatical setae. Scutellum lightly dusted on disc, margin on each side with four to five setulae between lateral and apical setae, one on each side situated slightly dorsal to the others and slightly stronger than them. Squamae pale with a gold margin and gold fringe. Wings slightly yellowish anteriorly. Wing length 4.0mm.

Legs: black with basal tarsomeres of all legs brownish.

Male terminalia; Figs. 49–52. In lateral view epandrium one and a quarter times wider than high, rather rounded with a blunt apical process, posteroventral and ventral margins bearing a few rows of moderately long setulae. Cerci forming a broad, rounded lobe half as high as epandrium, all margins with long setulae, a few longer ones present apically. Surstyli extending beyond the shell of the epandrium posteroventrally as a flat rather rounded lobe, also extending apically as a smaller lobe, teeth on basal lobe visible from the lateral aspect. In ventral view margins of surstyli with a fringe of short setulae, anteriorly with two rather “club-like” processes, basal plate bearing six very long, black and rather fine teeth. Aedeagus in the shape of a shallow letter U, with a single basal process slightly emarginate at the apex, upper sinuous part narrowing gradually towards apex, bearing a few small spicules basally.

Female: unknown

Differential diagnosis: There are many externally similar species present in south-east Asia but the brownish basal tarsomeres make this species stand out from the others. The male genitalia are the main guide in identifying this species, the broad epandrium, very long surstylar teeth and characteristic aedeagus distinguishes it from other Silba species. S. combi sp. nov. also has long surstylar teeth but differs from this species in having a taller epandrium, larger cerci, shorter and more numerous surstylar teeth and a much simpler aedeagus.

TYPE MATERIAL: Holotype male: THAILAND: Chiang Mai Prov., Chiangmai (Suandok), 330m, 18°79’N / 98°97’E, 29.x.2000, B. Merz.

Only known from the holotype which in the MHNG .

Etymology. The specific epithet refers to the long teeth present on the basal plate of the surstyli.