Sphegina (Asiosphegina) falcata, Hippa, Heikki, Steenis, Jeroen Van & Mutin, Valeri A., 2015

Hippa, Heikki, Steenis, Jeroen Van & Mutin, Valeri A., 2015, The genus Sphegina Meigen (Diptera, Syrphidae) in a biodiversity hotspot: the thirty-six sympatric species in Kambaiti, Myanmar, Zootaxa 3954 (1), pp. 1-67 : 32-33

Sphegina (Asiosphegina) falcata sp. n.

Figs 17 A–C

MALE. Body length 7.5 mm, wing length 6.4 mm. Head. Face strongly concave and strongly projected anteroventrally; frontal prominence strongly developed (similar to Fig. 1L). Width of vertex at anterior ocellus:width of head 1:3.6; depth of occipital concavity a little less than 1/4 of the width of an eye in dorsal view. Width of face:width of head 1:3.4. Face dorsally brown, ventrally yellow, pale pollinose. Gena shiny yellow. Frons and vertex shiny; lunula brownish; frontal prominence brown, the more posterior part black, weakly pale pollinose along eye margin; vertex with blue reflection; pile short, erect and reddish. Frontal prominence with small, rather deep depression. Occiput mainly dull black, except shiny dorso-medial part. Antenna brown; basoflagellomere large, oval, ratio of length:width 1.5:1.0; arista pilose. Thorax. Colour dull, weakly pollinose, dorsally black except postpronotum and postalar callus yellow, pleura yellowish except posterior part of anepisternum, entire anepisternum and katepimeron brown; the pile of scutum short and adpressed, reddish, scutellum rather trapezoid, shiny medially, the pile similar to posterior part of scutum, a pair of thin, long, pale, widely separated setae at apical margin. Wing. Slightly brownish, without any darker pattern, stigma darkened. Legs. Pro- and mesoleg yellow, protarsus mainly black, with whitish joints of tarsomeres; mesotarsus lost from the single specimen. Metaleg: coxa yellow; trochanter simple, yellow; femur yellow, the apical 1/6 brown, a faint trace of brownish annulus medially; tibia with small apico-ventral tooth, brownish but with a short basal part and a broad annulus on the apical 1/2 yellow; tarsus black. Abdomen. Length ratio of tergites I, II, III and IV 1:4.0:3.0:2.0. Tergites rather dull black, weakly pollinose; tergite III with an antero-medial oval yellow macula, tergite IV with a similar semicircular macula, the pile of tergites pale, short and adpressed, becoming longer towards the lateral margin; tergite I with 4 (3 on right side) strong, reddish setae at lateral margin, 2 placed anteriorly, the other two posteriorly and positioned above one another; sternite IV yellow, almost separated by postero-medial membranous part into two halves with long, pale pile along postero-lateral margin; sternites VI–VIII simple, brown, the pile pale. Genitalia, Figs 17 A–C. Note the symmetrical surstyli and superior lobes as well as the conspicuously trichose, large postero-medial part of aedeagus. FEMALE. Unknown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m, 12–17.vi.1934, R. Malaise ( SMNH).

Etymology. The name is Latin, falcata , sickle-shaped, referring to the shape of the superior lobe.

Discussion. Sphegina falcata is not especially similar to any other Sphegina . Except for the characters appearing in the key it is readily distinguished by the basally broad, apically narrow sickle-shaped and symmetric superior lobes and the large trichose submembranous ejaculatory hood. In the single studied specimen the two most posterior of the strong lateral setae on tergite II are placed one above the other, not in longitudinal row, unlike other Sphegina , except for some specimens of S. bidens and S. simplex we have seen.

Sphegina apicalis Shiraki, 1930 and S. varidissima Shiraki, 1930 are similar to S. falcata by the maculae on tergites III and IV, mainly dark protarsus, well developed frontal prominence, and hyaline wing without infuscate pattern. S. falcata differs from both by entirely pollinose scutum ( S. apicalis with 2 pollinose vittae medially, S. varidissima with 4 brownish pollinose vittae).

Figures

FIGURE 17. Sphegina (Asiosphegina) falcata sp. n. (holotype). A. Left surstylus, lateral view. B. Left superior lobe, lateral view. C. Genitalia, lateral view. Scale 0.5 mm.