Sphegina (Asiosphegina) nasuta, 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 : 37-38

Sphegina (Asiosphegina) nasuta sp. n.

Figs 1K, N, 2C, 21A–D

MALE. Body length 6.5 mm, wing length 5.5 mm. Head (Figs 1K, N). Face strongly concave and moderately projected antero-ventrally; frontal prominence strongly developed, moderately strongly projecting anteriorly. Width of vertex at anterior ocellus:width of head 1:4.5; depth of occipital fossa ca. 1/3 of the width of an eye in dorsal view. Width of face:width of head 1:4.5. Face yellow, dorsally brownish, densely pale pollinose. Gena shiny yellow. Frons and vertex shiny black; lunula brown, a lateral macula of pale pollinosity posteriorly from the frontal prominence; the pilosity scarce, short, erect and pale. Occiput dull black, semi-shiny dorsally. Antenna yellow; basoflagellomere unusually elongated, nearly twice as long as broad [ratio of length:width 1.5:1.0]; arista missing in the studied specimens. Thorax. Colour mainly reddish, postpronotum and anepimeron yellowish, the hair yellowish; scutum brown or black, reddish or yellowish laterally and with weak reddish submedial vittae, the pile adpressed and golden; scutellum semitriangular [ratio of length:width 1:2.8], with the pile similar to that on posterior part of scutum, with a pair of very thin setae at apical margin the same length as the scutellum; all parts slightly pale pollinose, scutellum rather shiny. Wing. ( Fig. 2 C). Rather hyalinous, infuscated along transversal veins, stigma yellow. Legs. Proleg yellow, basotarsomere yellowish with black macula near apex, tarsomeres 2 and 3 black except yellowish margins, 4 and 5 black entirely; tarsus distinctly enlarged and flattened. Mesoleg yellow, apex of tarsomere 3 and whole tarsomeres 4 and 5 blackish. Metaleg: coxa brownish; trochanter simple, brownish; femur: basal 1/4 yellowish, submedial annulus brownish, extended dorsally, apical 1/5 brown, subapical part yellow; tibia without apico-ventral tooth, brownish, the basal 1/4 and a submedial annulus yellow; tarsus brown.

Abdomen: Length ratio of tergites I, II, III and IV 1:3.5:2.5:1.6. Colour of tergites shiny black, tergite III with a narrow reddish fascia at anterior 1/4, tergite IV reddish anteriorly, the pile of tergites short, dark and adpressed, becoming longer and paler laterally; tergite I with 1–2 well separated, strong, reddish setae at lateral margin; sternite IV ( Fig. 21 C) unusually symmetrical, anteriorly brown and yellow posteriorly, the pile and the stronger seta-like postero-lateral pile all pale; sternites VI–VIII simple, black, the pile dark. Genitalia, Figs 21 A, B, D. Note the symmetrical surstyli and superior lobes and the large and complicated aedeagus. FEMALE. Unknown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m, 28.v.1934, R. Malaise ( SMNH). PARATYPE. 1♂ with same data as holotype except 25.v. ( NBC).

Etymology. The name is Latin, nasuta , large-nosed, referring to the strongly protruding ventral part of head.

Discussion. Sphegina nasuta resembles S. bidens and S. simplex . Except for the characters appearing in the key it differs as follows: 1) tergite I with 1–2 strong black setae at lateral margin ( S. bidens 3, S. simplex 2–3), 2) basoflagellomere elongated (short oval), 3) postalar callus black (brown), 4) tergites III and IV with red fascia anteriorly (S. simplex with yellow to red macula on both, S. bidens with anterior 1/3 of tergite III yellow). In male genitalia S. nasuta differs from the two other discussed species by having the ventral lobe of surstylus very large and apically pointed, in S. bidens the lobe has no distinct apex at all and in S. simplex the whole ventral lobe is almost lacking.

Sphegina nasuta is also similar to S. orientalis Kertész, 1914 and has a similarly modified protarsus. S. orientalis differs e.g. by having a truncate, not pointed ventral lobe of the surstylus, and tergites II, III and IV with yellow anterior fascia.

Figures

FIGURE 2. Wing. A. Sphegina (Sphegina) uncinata sp. n. (paratype). B. S. (Asiosphegina) furva sp. n. (paratype). C. S. (A.) nasuta sp. n. (paratype). D. S. (A.) crucivena sp. n. (paratype). E. S. (A.) crassispina sp. n. (paratype). F. S. (A.) bidens sp. n. (paratype). G. S. (A.) carinata sp. n. (paratype). H. S. (A.) index sp. n. (paratype). I. S. (A.) simplex sp. n. (paratype). Scale 0.5 mm.

FIGURE 21. Sphegina (Asiosphegina) nasuta sp. n. (holotype). A. Left surstylus, lateral view. B. Left superior lobe, lateral view. C. Sternite IV, ventral view. D. Genitalia, lateral view. Scale 0.5 mm.