Silba media, Macgowan & Tschirnhaus, 2024

Macgowan, Iain & Tschirnhaus, Michael Von, 2024, Records of Lonchaeidae (Diptera, Cyclorrhapha) from Togo and other African countries, with descriptions of new species, Zootaxa 5514 (1), pp. 1-27 : 9-10

Silba media sp. nov. ( Figures 21–23 )

Description: Holotype male: Head: Eye bare. Frons sub-shining black, dulled by brownish pollinosity and microsculpture. Ratio of frons width at point just above lunule to eye width 0.4:1 Orbital plate bare apart from the orbital seta, sub-shining black, dulled by microsculpture. Frontal and interfrontal setulae short, at most 0.1x length of orbital seta, longer setulae present just on margin above lunule. Lunule, ground colour black, parafacial and face slightly grey pollinose. Antenna, postpedicel black, length to depth ratio approximately 2.1:1. Arista yellowish basally, width of plumosity at maximum approximately the depth of postpedicel, individual plumes bent anteriorly at apex. Anterior genal setulae in a single row of 5–6 along mouth margin, basal to these a strong seta, almost twice as long and strong as the other setulae on the gena. Palpus black.

Thorax: Mesonotum sub-shining blue-black, with a covering of short setulae, these approximately 0.3x length of the orbital seta. Anepisternum with a vertical row of three anterior and three posterior setae. One seta on proepimeron and one on proepisternum. Katepisternum with two setae near the dorsal margin, the posterior slightly stronger and positioned slightly more dorsad than the anterior, a scattering of short setulae located along the anterior margin of this sclerite otherwise the surface is bare. Scutellum covered with grey pollinosity, on margin with three setulae between apical and lateral setae on each side, two between apical setae. Calypter whitish with a white fringe of uniform length. Wing clear with pale brown veins, wing length 3.7mm. Haltere dark. Legs entirely dark.

Male terminalia: In lateral view epandrium at least 2x as high as it is wide, only slightly sclerotised dorsally, bearing strong setae on posterior and ventral margins. Surstylus extending beyond the shell of the epandrium anteriorly as a rounded lobe, prensisetae visible at the base of the cercus. Cercus 0.3x the height of the epandrium, bearing long, strong setae along posterior and ventral margins. In ventral view, five peg-like black prensisetae forming a row on posterior margin of surstylus, a further single prensisetae located medially one third of the way from posterior to anterior margin and a further one at the half way point. Ventral margin of surstylus bearing 9–10 very strong setae posteriorly, the more anterior of them gradually becoming weaker. Postgonites large, square shaped and setulose. Phallus, distiphallus a straight tube, slightly recurved at apex, basiphallus boat shaped with a pair of short, rounded apical processes which enclose the base of the distiphallus.

Female: Unknown.

Diagnosis. This species with its long, narrow epandrium and the presence of isolated prensisetae near the median point of the ventral margin of the surstylus in addition to those on the posterior margin is distinctive from other described Silba species. In the paratype there are three prensisetae medially on the surstylus rather than the two in the holotype. The phallus, with the distiphallus arising between two short rounded apical lobes of the basiphallus, is also characteristic. The single strong seta on the genae is also a feature of this species.

Type material. Holotype: ♂. TOGO: Région des Plateaux: Kodjo-Kopé N of Badou, at creek Djodji , coordinates: 7.648N 0.595E, 24.4.200 8, cocoa, oil palm plantation, leg. M. von Tschirnhaus. Specimen deposited in SDEI; SDEI-Dip-01002.

Paratypes: 1♂, CAMEROON: Route 9, 20km E. of Sangmelima, 7.11.198 7, leg. A. Freidberg. 1♂, UGANDA: Ruwenzori Mts , Ibanda, 1900m, 4.1.199 6, leg. I. Yarom & A. Freidberg. Both specimens deposited in SMNHTAU .

Additional material: 1♂, DEMOCRATIC REPUBLIC OF CONGO: Eala, 14.5.193 6, leg. J. Ghesquière, Specimen deposited in RBINS .

Etymology. The specific epithet refers to the medial position of some of the prensisetae on the inner surface of the surstylus.

Figures

FIGURES 21–24. Silba media sp. nov. 21. Epandrium and associated structures, lateral view. 22. Same, ventral view. 23. Inner surface of surstylus, 24. Phallus, lateral view.