Sphegina (Asiosphegina) subradula, 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 : 30-31

Sphegina (Asiosphegina) subradula sp. n.

Figs 16 A–E

MALE. Body length 6.5–8.0 mm, wing length 5.5–6.5 mm. Head. Face strongly concave, weakly projected antero-ventrally; frontal prominence weakly developed (similar to Fig. 1F). Width of vertex at anterior ocellus more than 1/4 of the width of head [1:3.6]; the depth of occipital fossa:width of an eye in dorsal view is 1:3.7. Width of face:width of head is 1:4.6. Face ventrally brownish, weakly pale pollinose, dorsally blackish and densely pale pollinose. Gena shiny yellow. Frons dull black; lunula shiny brown, a narrow pale pollinose vitta behind and at side of frontal prominence; the pile short and scattered; vertex dull black. Occiput dull black. Antenna brown; arista pilose. Thorax. Colour black, more or less densely pale pollinose; postalar callus yellowish; the pile of scutum short and adpressed, reddish and black, posteriorly intermixed with longer erect pile; scutellum shorttrapezoidal, ratio of length:width 1:2.8, pile pale, with a pair of long, thin rather widely separated pale setae at apical margin. Wing. Hyaline; stigma yellowish. Legs. Proleg yellow, tarsomeres 4 and 5 black or brown. Mesoleg yellow, femur for the most part dark except basal 1/4 and extreme apex yellow, tarsomeres 4 and 5 blackish. Metaleg: coxa brownish; trochanter simple, yellow; femur strongly thickened, dark brown with the basal 1/3 yellow; tibia with small apico-ventral tooth, the basal 3/5 yellow, apical 2/5 brown, sometimes with distinct narrow dark annulus near middle; tarsomeres brown. Abdomen. Length ratio of tergites I, II, III and IV 1:3.3:2.0:1.3; colour of tergite black, anterior 1/3 of tergite III yellow; pile pale, short and adpressed, becoming longer laterally; tergite I with 3 modified setae at lateral margin, the first one thin, long and pale, the second and third ones shorter and thick, convergent, dark or the third one pale; sternite IV ( Figs 16 A, B) brown, pile pale, the strong setae and bristles black mixed with yellow ones, their number and arrangement variable; sternite VI with a rounded conical tubercle on posterior 1/2, black, the pile rather short adpressed and pale; sternites VII and VIII black, the pile short and pale. Genitalia, Figs 16 C–E. Note the strongly asymmetrical surstyli and slightly asymmetrical superior lobes, the medial lobe at the base of the dorsal lobe of the left side surstylus and the long aedeagal lobe. FEMALE. Body length 6.8–7.9 mm, wing length 6.2–7.2 mm. Similar to male except for the normal sexual dimorphism. Abdomen mainly black except dorsally dark-yellow anterior macula on tergite III; tergite V entirely orange-brown; length ratio of tergites I, II, III and IV 1:2.8:2.1:1.8; tergite I with 2 strong yellow lateral setae on posterior 1/2, sometimes posterior seta black; ratio of length:width of tergite III and IV 1:1.4 and 1:1.7; tergite V broad with long pale erect pile; sternite IV oval, brown, pile short, pale; sternite V rectangular, rounded posteriorly, with very long pale pile posteriorly.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 7000 ft., 25.v.1934, R. Malaise ( SMNH). PARATYPES. 1♀ with same data as holotype except 23.v. ( SMNH); 1♂ and 2♀ with same data except 12–17.vi. ( SMNH, NBC); 1♀ with same data except 7000 ft. 15.v. ( SMNH).

Etymology. Modified from the name of S. radula by adding the Latin prefix -sub, almost, referring to the close similarity of the two species.

Discussion. Sphegina subradula is similar to S. radula . Except for the characters appearing in the key it differs by having the male superior lobe narrower, without a ventral angular sublobe, and by having the left side surstylus very broad on the basal half. Also, the aedeagal lobe is longer than in S. radula . By male sternite IV the two species may be indistinguishable. S. subradula is also similar to S. radula and S. raduloides . For more discussion, see under the latter.

Figures

FIGURE 16. Sphegina (Asiosphegina) subradula sp. n. (A, C, D, E holotype, B paratype). A. Posterior part of sternite IV, sternite V and sternite VI, ventral view; the unmodified pilosity omitted. B. Posterior part of sternite IV, ventral view; the unmodified pilosity omitted. C. Genitalia, lateral view. D. Left surstylus, lateral view. E. Left superior lobe, lateral view. Scale 0.5 mm.