Silba andasibe, Macgowan, 2019

Macgowan, Iain, 2019, New species of Lonchaeidae Diptera: Schizophora) from Madagascar, Israel Journal of Entomology (Oxford, England) 49 (2), pp. 223-242 : 226-228

Silba andasibe n. sp.

( Figs 6–8)

LSID: urn:lsid:zoobank.org:act:C8ADA2ED-1C3F-400A-B3A1-B508EF62B6D5 .

Etymology: The specific epithet relates to the capture site of the holotype and is a noun in apposition.

Differential diagnosis: The epandrium with an obvious 9 th tergite is apparently unique amongst the described species of Silba . This tergite is evident in Lonchaea species in the Lonchaea polyhamata McAlpine, 1964 species-group (MacGowan 2018) and all known Fulgenta species and may well represent a primitive condition within the family. The row of three closely situated rounded prensisetae, the asymmetrical pregonites with the left being very long and chitinised and the unique phallus serve to distinguish this species from other Silba species.

Description: Male. Head: Eyes bare. Frons sub-shining black, frontal and interfrontal setulae very short, approximately 0.15× length of orbital seta. Lunule, base colour black, when viewed from above covered with moderately dense silver pollinosity, this extending onto parafacials and face. Anterior genal setulae in a single row along mouth margin, none of these particularly strong.Antennae black, postpedicel orange at extreme medial base, length to depth ratio 2.5:1. Arista plumose, ratio of plumosity at maximum extent to depth of postpedicel 1:1.

Thorax: Scutum shining blue-black. Anepisternum with three anterior and three 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 five multiserial setulae on right, two on left, two very short setulae between apical setae. Calypteres pale, with golden margin and fringe. Wings slightly fumose anteriorly, veins brownish, wing length 4.5 mm. All femora and tibiae dark brown, contrasting with the dark setulae and setae (this may be age related fading) tarsomeres entirely black.

Male terminalia: Epandrium with 9 th and 10 th tergites not completely fused, 9 th tergite a rounded lobe, thin and lightly sclerotized, attached to anterior surface of 10 th tergite, 10 th tergite spherical, bearing numerous rather short setulae on ventral margins. Cerci relatively small, bearing numerous short setulae. Surstyli contained within shell of epandrium, with a multiple row of short setulae along ventral margin. Inner surface of surstylus with almost fused row of three rounded prensisetae situated below base of cerci, strong inwardly pointing seta arising from near base of prensisetae, loose row of setulae lying anterior to them. Left pregonite greatly enlarged and sclerotized, forming long, black pointed projection, right pregonite insignificant. Postgonites large and sclerotized. Phallus large open U-shaped, simple basally, on apical third with two long, slender processes, one longer than apex of phallus, other shorter, apex of phallus ribbon-like with numerous small setulae on shaft and especially at apex.

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

Paratype: Madagascar: 1 ♂ with the same data as the holotype .