Sphegina (Asiosphegina) bilobata, 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 : 41

Sphegina (Asiosphegina) bilobata sp. n.

Figs 1L, O, 3A, 24A–D

MALE. Body length 7.5–7.8 mm, wing length 6.0– 6.2 mm. Head (Figs 1L, O). Face strongly concave and strongly projected antero-ventrally; frontal prominence strongly developed. Width of vertex at anterior ocellus:width of head 1:3.9; depth of occipital fossa 1/3 of the width of an eye in dorsal view. Width of face:width of head 1:4.5. Face yellow, pale pollinose. Gena shiny yellow. Frons and vertex dull black, with a pair of pale pollinose maculae behind frontal prominence; lunula yellow; frontal prominence brownish, almost yellow anteriorly, with medial groove, the pile short, erect and pale. Occiput dull black. Antenna entirely yellow; basoflagellomere enlarged, nearly 1.5 times as long as broad; arista short pilose. Thorax. Colour dull yellow or yellowish scutum with a black medial fascia and a black sublateral fascia which is interrupted at the transverse suture, the pile short, adpressed and pale; scutellum trapezoid, ratio of length:width 1:2.3, shiny yellow or yellowish brown, the pile similar to posterior part of scutum, a pair of thin, long, pale, widely separated setae at apical margin. Wing. Hyalinous, stigma yellowish, the pattern brownish. Legs. Pro- and mesoleg yellowish; protarsus and tarsomere 5 on mesotarsus brown. Metaleg ( Fig. 3 A): coxa brownish; trochanter simple, yellow; femur yellow, the apical 1/6 brownish and a ventrally interrupted annulus on the basal 1/2 weakly brownish; tibia with an apico-ventral tooth, colour yellow except the apical 1/5 brown and an annulus on the basal 1/2 brownish; tarsus brown. Abdomen. Length ratio of tergites I, II, III and IV 1:3.8:2.5:2.0. Tergites shiny brownish, tergites III and IV with a yellowish medially almost interrupted fascia on the anterior 1/2, the pile of tergites pale, short and adpressed, becoming longer towards the lateral margin; tergite I with an oblique row of 3 long, pale, rather thin setae laterally; sternite III ( Fig. 24 D), unusually well-developed, pale, with black setae; sternite IV ( Fig. 24 D) nearly symmetrical, pale yellow, the pile long erect and pale, the strong bristles on the posterior lobes black; sternites VI–VIII simple, brownish, the pile pale yellowish. Genitalia, Figs 24 A–C. Note the symmetrical surstyli and superior lobes and the large partly non-setose cercus. FEMALE. Body length 8.4 mm, wing length 7.5 mm. Similar to male except for the normal sexual dimorphism. Protarsus yellow with tarsomere 5 obscure brownish yellow. Metaleg ( Fig. 3 A) paler than in the male; femur almost entirely yellow, tibia without a distinct apicoventral tooth, with brownish subbasal annulus and apex; tarsus brownish dorsally. Abdomen entirely yellow; length ratio of tergites I, II, III and IV 1:3.3:2.1:1.6; sternites III and IV elongated, with distinct medial notch posteriorly, pile short and pale; tergite V semitriangular with short pale pile; sternite V semi-rectangular, shorter than broad, with pale pile.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m, 11.v.1934, R. Malaise ( SMNH). PARATYPES. 1♀ with same data as holotype except 18.v. ( SMNH); 1♂ with same data except 7000 ft., 5.v. ( BMNH); 1♂ with same data except 7000 ft., 14.v. ( SMNH); 1♂ with same data except 7000 ft., 9.vi. ( NBC).

Etymology. The name is Latin, bilobata , two-lobed, referring to the posteriorly two-lobed male sternite IV.

Discussion. Sphegina bilobata is not especially similar to any other described Sphegina . It is easily distinguished in both sexes by its pale yellowish general colour with three black longitudinal stripes on the scutum in combination with the infuscated pattern at cross veins on the wing. The male sternite IV with its symmetrical pair of short spinose lobes posteriorly is quite unique. Even the male genitalia do not have any close similarity to other species.

Figures

FIGURE 3. Metaleg, prolateral view (A, D female, B, C, E male). A. Sphegina (Asiosphegina) bilobata sp. n. (paratype). B. S. (A.) forceps sp. n. (paratype). C. S. (A.) minuta sp. n. (paratype). D. S. (A.) gigas sp. n. (paratype). E. S. (A.) carinata sp. n. (paratype). Scale 1.0 mm.

FIGURE 24. Sphegina (Asiosphegina) bilobata sp. n. (holotype). A. Left surstylus, lateral view. B. Left superior lobe, lateral view. C. Genitalia, lateral view. D. Posterior part of abdomen, ventral view. Scale 0.5 mm.