Sphegina (Asiosphegina) radula, 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 : 27-29

Sphegina (Asiosphegina) radula sp. n.

Figs 1D, G, 4C, 14A–F

MALE. Body length 6.0– 7.2 mm, wing length 5.0– 6 mm. Head (Figs 1D, G). Face weakly concave and moderately projected antero-ventrally; frontal prominence weakly developed. Width of vertex at anterior ocellus:width of head 1:3.6; the depth of occipital fossa ca. 1/4 of the width of an eye in dorsal view [1:4.3]. Width of face: width of head is 1:3.9. Face brown, ventrally paler and shiny, dorsally darker and densely pale pollinose. Gena shiny brown. Frons with a shallow, broad medial depression; colour black, lunula shiny, behind lunula pale pollinose, the pollinosity weaker posteriorly, short pale scattered pile along eye margin; vertex dull black. Occiput dull black. Antenna brown; basoflagellomere rounded reddish on ventral 1/2; arista pilose. Thorax. Colour black to brown, laterally paler than dorsally; scutum dull black, with more or less distinct medial and sublateral pale pollinose fascia; the pile short and adpressed, reddish or yellow, posteriorly intermixed with longer erect pile; scutellum transversal, trapezoid [ratio length:width 1:2.8] with concave apical margin; pile pale; a pair of long, widely separated pale setae at apical margin. Wing. Hyaline, stigma yellowish. Legs. Pro- and mesoleg yellow, tarsomeres 4 and 5 black to brown. Metaleg: coxa brownish; trochanter simple, yellowish; femur strongly thickened, dark brown, the basal 1/3 yellow; usually basally with a few thin black setullae, which are smaller than ventral setae; metatibia without apico-ventral tooth, brown, the basal 1/3 and narrow yellow medial annulus; tarsus black or brown. Abdomen. Length ratio of tergites I, II, III and IV 1:3.0:2.0:1.5. Colour of tergite black, anterior 1/ 3 of tergite III yellow; pile pale or sometimes with black pile on tergites II and III postero-laterally, short and adpressed, becoming longer laterally; tergite I ( Fig. 4 C) with 3 widely separated strong setae at lateral margin, the anterior one pale and weaker, the posterior ones black and stronger; sternite IV ( Figs 14 A–D) black, pile pale, the number and arrangement of the strong setae and bristles variable, their colour black or mixed black and yellow; sternite VI ( Fig. 14 C) black, the pile long and pale; usually with weakly visible trace of a rounded tubercle on posterior 1/2; sternites VII and VIII black, the pile long and pale. Genitalia, Figs 14 E, F. Note the asymmetrical surstyli, nearly symmetrical superior lobes and the short aedeagal lobe. FEMALE. Body length 6.0–7.0 mm, wing length 5.0–6.0 mm. Similar to male except for the normal sexual dimorphism. Abdomen mainly black, except dorsally an indistinct reddish anterior fascia on tergite III; length ratio of tergites I, II, III and IV 1:3.2:2.5:1.8; tergite I usually with 2 clearly separated strong black setae on apical 1/2 laterally, sometimes anterior seta yellow; ratio of length:width of tergite III and IV 1:1.3 and 1:1.4; tergite V brown with long pale erect pile; tergite VI divided medially by membranous stripe, with very long pale pile; sternite IV trapezoid, about 2 times as long as broad, brown, pile short, pale; sternite V semirectangular, rounded posteriorly, with very long pale pile posteriorly.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m, 11.v.1934, R. Malaise ( SMNH). PARATYPES. 1♂ with same data as holotype except 28.iv. ( SMNH); 1♂ with same data except 18.v. ( SMNH); 5♂ with same data except 25.v. ( SMNH, NBC); 1♂ and 1♀ with same data except 29.v. ( SMNH, NBC); 1♂ and 2♀ with same data except 4.vi. ( SMNH, NBC); 1♂ and 2♀ with same data except 11.vi. ( SMNH, NBC); 4♂ and 3♀ with same data except 12–17.vi. ( SMNH, NBC); 1♂ with same data except 17.vi. ( SMNH); 1♀ with same data except 1800 m, 28.v. ( SMNH); 1♂ with same data except 7000 ft., 2.v. ( BMNH); 4♂ with same data except 7000 ft., 14.v. ( SMNH, NBC); 1♂ with same data except 7000 ft., 15.v. ( SMNH); 5♂ with same data except 7000 ft., 16.v. ( SMNH, NBC); 2♂ with same data except 7000 ft., 18.v. ( SMNH, BMNH); 1♂ with same data except 7000 ft., 23.v. ( SMNH); 2♂ with same data except 7000 ft., 28.v. ( SMNH, NBC); 1♂ with same data except 7000 ft., 1.vi. ( SMNH); 1♂ with same data except 7000 ft., 2.vi. ( SMNH); 1♂ with same data except 7000 ft., 4.vi. ( SMNH); 3♂ with same data except 7000 ft., 7.vi. ( BMNH); 3♀ with same data except 7000 ft., 9.vi. ( SMNH, NBC).

Etymology. The name is Latin, radula , scraper, referring to the scraper-like impression given by the male sternite IV.

Discussion. Sphegina radula is similar to S. raduloides , S. subradula and S. trichaeta . Except for the characters mentioned in the key, it differs from these e.g. by having an angular lobe at the ventral margin of male superior lobe on both sides, from S. subradula and S. trichaeta by much narrower dorsal lobe of the left side surstylus and from S. raduloides by having the latter dorsally smoothly curved, not angular. The aedeagal lobe is short as in S. radula . Male sternite IV is rather variable concerning the size, number and exact placement of the spinose setae and the species may be difficult to distinguish from S. subradula and S. raduloides by this character complex. From S. trichaeta all the mentioned species differ by lacking conspicuously long strong setae on the left side of the male sternite IV. According to its original description S. nigrapicula Huo, Ren & Zheng, 2007 is similar to S. radula , S. raduloides and S. subradula but has black gena (brown in S. radula , yellow in S. raduloides and S. subradula ), and at least partly brownish femur and tibia of pro- and mesolegs (yellow in all three other species).

Figures

FIGURE 4. Tergite I (A – E), lateral view, abdomen (F, G, H), dorsal view. A, F. Sphegina (Asiosphegina) simplex sp. n. (paratype). B. S. (A.) gigas sp. n. (paratype). C. S. (A.) radula sp. n. (paratype). D, H. S. (A.) crassispina sp. n. (paratype). E, G. S. (A.) parvula sp. n. (paratype). Scale 0.5 mm for A – E, 1 mm for F, G, H.

FIGURE 14. Sphegina (Asiosphegina) radula sp. n. (A, B, C, D paratype, E, F holotype). A, B, D. Sternite IV, ventral view; the unmodified pilosity omitted. C. Posterior part of sternite IV, sternite VI and sternite VII, ventral view; the unmodified pilosity omitted. E. Genitalia, lateral view. F. Left surstylus and superior lobe, lateral view. Scale 0.5 mm.