Sphegina (Asiosphegina) pollex, 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 : 61-63

Sphegina (Asiosphegina) pollex sp. n.

Figs 40 A–D

MALE. Body length 4.6–4.9 mm, wing length 4.4–4.8 mm. Head. Face strongly concave and weakly projected antero-ventrally; frontal prominence very weakly developed (similar to Fig. 1E). Width of vertex at anterior ocellus ca. 1/4 of the width of head [1:3.8]; depth of occipital fossa ca. 1/6 of the width of an eye in dorsal view. Width of face:width of head 1:3.8. Face and gena dark, densely pale pollinose. Frons and vertex mainly weakly pollinose, semi-shiny black; lunula shiny brown; the pile short, erect and pale, behind frontal prominence with small oval depression. Occiput dull black. Antenna dark brown, basoflagellomere baso-ventrally reddish; arista pilose. Thorax. Colour black, pale pollinose; scutum with a medial and sublateral semi-shiny fascia, the pile adpressed, reddish; scutellum semicircular, densely pale pollinose, the pile similar to that on posterior part of scutum, a pair of thin, long, black setae at apical margin. Wing. Hyaline, stigma very pale. Legs. Pro- and mesoleg yellow, tarsomeres 4 and 5 black. Metaleg: coxa brownish; trochanter simple, yellow; femur blackish, basal 1/3 yellow, without black setae ventrally on the yellow part; tibia without apico-ventral tooth, colour yellow, the apical 1/4 black and an obscure brownish annulus on the basal 1/2; tarsus black. Abdomen. Length ratio of tergites I, II, III and IV 1:3.4:2.3:1.9. Colour of tergites shiny black, tergite III and IV with a yellow medially interrupted fascia anteriorly; pile of tergites pale, short and adpressed, becoming longer laterally; tergite I with an oblique row of 3 long pale setae laterally; sternite IV ( Fig. 40 A) shiny black except yellow posterior margin, the pile pale, longer posteriorly; sternites VI–VIII simple, black, the pile pale; sternite VIII with pile longer than on sternite VII. Genitalia, Figs 40 B–D. Note the nearly symmetrical surstyli and superior lobes, the thumb-like lobe baso-medially on the dorsal lobe of surstylus and the slightly modified cercus. FEMALE. Unknown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m, 12–17.vi.1934, R. Malaise ( SMNH). PARATYPES. 1♂ with same data as holotype except 12–17.vi. ( NBC); 1♂ with same data except 7000 ft., 12.v. ( SMNH); 1 male with same data except 7000 ft., 14.v ( NBC).

Etymology. The name is Latin, pollex , thumb, referring to the thumb-like lobe on the dorsal lobe of the surstylus.

Discussion. Sphegina pollex is similar to S. culex . Except for the characters mentioned in the key it differs by having the membranous incision at the posterior margin of male sternite IV small and by having a thumb-like subbasal sublobe dorso-medially on the dorsal lobe of the surstylus. In both species the superior lobe is similar to that of S. achaeta but the postero-dorsal lobe-like part is rounded (acute in S. achaeta ).

Sphegina apicalis Shiraki, 1930 is similar to S. pollex based on the medially interrupted fascia on tergites III and IV and the pollinose vittae on mesonotum but S. apicalis differs by a more strongly projecting frontal prominence ( S. pollex weakly projecting) and predominantly dark pro- and mesotarsus ( S. pollex with only tarsomeres 4 and 5 dark).

Figures

FIGURE 40. Sphegina (Asiosphegina) pollex sp. n. (holotype). A. Posterior part of sternite IV, ventral view. B. Left surstylus, lateral view. C. Left superior lobe, lateral view. D. Genitalia, lateral view. Scale 0.5 mm.