Silba longigonite, Macgowan, 2019

Macgowan, Iain, 2019, New species of Lonchaeidae Diptera: Schizophora) from Madagascar, Israel Journal of Entomology (Oxford, England) 49 (2), pp. 223-242 : 228-230

Silba longigonite n. sp.

( Figs 9–13)

LSID: urn:lsid:zoobank.org:act:20143B64-A464-4F4E-ACBF-09C60723B481 .

Etymology: The species name relates to the long pregonites.

Differential diagnosis: On external characters this is a rather standard Silba species apart from the brownish legs; it is unclear whether or not this is just a feature of ageing. The main specific characters are in the structure of the male terminalia, in particular in only having three distinct prensisetae on the posterior margin of each surstylus and a very small, simple phallus.

Description: Male. Head: Eyes bare. Frons sub-shining black, frontal and interfrontal setulae very short, less than 0.1× length of orbital setae, a few longer setulae on anterior margin. Orbital plates shining, bare apart from orbital seta. Lunule, ground colour dark, when seen from above lunule, parafacials and face lightly silver pollinose.Anterior genal setulae in a single row of six along mouth margin, stronger basally but these not noticeably stronger than other setulae on genae.Antennae black; postpedicel slightly orange at extreme medial base, length to depth ratio 2.6:1. Arista plumose, ratio of plumosity at maximum extent to depth of postpedicel 1:1.

Thorax: Scutum shining blue-black. Anepisternum with four anterior setae (one of these on right side is rather weak) and three rather long, curving posterior setae. Katepisternum with two setae located near dorsal margin, anterior only slightly shorter and weaker than posterior. Scutellum, on margin between lateral and apical setae, with three setulae on each side, two between apical setae. Calypteres entirely pale, with a uniform pale fringe. Wings clear, veins brownish, wing length 4.0 mm. Legs brown, contrasting with black setulae, tarsomeres appearing darker due to density of setulae.

Male terminalia: Epandrium in lateral view rather circular, slightly wider than high, with numerous setulae on posterior and ventral surfaces. Cerci small, 0.3× height of epandrium, not sclerotized, bearing numerous rather stiff setulae, these thicker and shorter on ventral surface. Surstylus contained within shell of epandrium, inner surface with three well-spaced prensisetae along posterior margin, a single row of relatively long setulae along ventral margin with a slightly multiserial row lying just anterior to these, a pair of stiff setulae situated centrally below base of cerci. Pregonites long and finger like, directed posteriorly at apex, setulose basally with a small lateral process on outer surface. Postgonites large with setulose margins. Phallus simple U-shaped.

Holotype: ♂ Madagascar: Andasibe , Analamazaotra forest, 18°56'S 48°24'E, 950 m, 31.x–4.xi.2007, L. Friedman (SMNHTAU).