Silba setigonite, Macgowan, 2019

Macgowan, Iain, 2019, New species of Lonchaeidae Diptera: Schizophora) from Madagascar, Israel Journal of Entomology (Oxford, England) 49 (2), pp. 223-242 : 232-234

Silba setigonite n. sp.

( Figs 18–21)

LSID: urn:lsid:zoobank.org:act:173170CE-C023-454D-8FD4-74E48FC67EF8 .

Etymology: The species name reflects the coat of setulae on the pregonites.

Differential diagnosis: The unusual features of the epandrium and surstyli along with the large ventrally directed prensisetae make this an easily identifiable species distinct from any previously described Silba species.

Description: Male. Head: Eyes bare. Frons sub-shining black, dulled by microsculpture, frontal and interfrontal setulae very short, at most 0.2× length of orbital seta, longer on anterior margin above lunule. Lunule with brownish ground colour, when seen from above moderately silver pollinose as are parafacials and face. Anterior genal setulae in a single row of 7–8 along mouth margin, decreasing in length anteriorly. Antennae, postpedicel black apart from a small orange area at extreme medial base, length to depth ratio 2.8:1. Arista plumose, ratio of plumosity at maximum extent to depth of postpedicel 1.1:1.

Thorax: Scutum shining blue-black contrasting with the rather matt grey-black scutellar dorsum. Anepisternum with four anterior setae and four posterior setae, remainder of sclerite covered in rather sparse, long setulae. Katepisternum with two setae located near dorsal margin, anterior being slightly shorter and weaker than posterior. Scutellum, on margin between lateral and apical setae, with three setulae on each side, none between apical setae. Calypteres pale, with a pale margin and fringe. Wings clear, veins brownish, wing length 4.0 mm.All femora and tibiae dark brown, contrasting with dark setulae and setae, tarsomeres dark.

Male terminalia: In lateral view epandrium of unusual shape, with moderately large rectangular process posteriorly behind which one of strong prensisetae projects, a row of very long setulae present along posterior and ventral margins. Cerci relatively small, slightly rectangular in shape, bearing numerous short setulae. Surstyli extending beyond shell of epandrium posteroventrally as large semicircular lobe. Inner surface of surstyli with two prensisetae, a smaller, medially directed posterior prensiseta located just below base of cerci. A much larger ventral prensiseta directed ventrally, extending beyond outer margin of surstylus, otherwise inner surface with only a few small setulae near ventral margin. Pregonite, moderately large, simple processes, pointed at apex, covered in numerous short setulae. Postgonite, relatively small with short marginal fringe of setulae. Phallus relatively simple, slightly angular, J-shaped tube without ornamentation apart from area of small scales medially.

Holotype: ♂ Madagascar: Mandraka, Rt. 2, 75 km E Antananarivo [18°57'S 47°54'E], 16.iv.1991, A. Freidberg & F. Kaplan (SMNHTAU).

Paratypes: Madagascar: 1♂ Ambohitra, Joffreville , 800 m, 9–12.iv.1991, A. Freidberg & F. Kaplan (SMNHTAU) ; 1♂ NosY, TanikelY, 6.iv.1991, A. Freidberg & F. Kaplan (SMNHTAU); 1♂ Andasibe, Hotel Feon’nYala, 5.xi.2007, L. Freidman (SMNHTAU) ; 1♂ Tananarivo [= Antananarivo], no date, S. V. Friederichs ( MNB). Note: The specimen in the Museum für Naturkunde, Berlin has no further data on the label but according to Enderlein (1920) Dr Friederichs was in Madagascar in 1916 and this is considered the likely date of collection .