Sphegina (Asiosphegina) index, 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 : 19-21

Sphegina (Asiosphegina) index sp. n.

Figs 2 H, 9A–E

MALE. Body length 7.6 mm, wing length 6.0 mm. Head. Face strongly concave and moderately projected anteroventrally; frontal prominence weakly developed (similar to Fig. 1J). Width of vertex at anterior ocellus a little more than 1/4 of the width of head; depth of occipital fossa ca. 1/3 of the width of eye in dorsal view. Width of face:width of head 1:3.9. Face black, medio-ventral part brownish, pale pollinose. Gena shiny black. Frons and vertex dull black; lunula shiny brown. Occiput dull black. Antenna brown, basoflagellomere darker dorsally; arista pilose. Thorax. Colour blackish, weakly pollinose; postalar callus brownish; scutum semi-shiny, with a pair of indistinct darker submedial fascia; pile short, adpressed, reddish; scutellum short, about 2.5 times broader than long, apically rounded; the pile similar to that on scutum; with a pair of long thin, dark, setae at apical margin. Wing, Fig. 2 H.

Hyalinous, the infuscated pattern brownish, stigma yellowish. Cross vein dm-cu perpendicular to vein M1+2, slightly s-curved; vein M1 straight. Legs. Pro- and mesolegs yellow; tarsomeres 4 and 5 black. Metaleg: coxa brownish; trochanter yellow, simple; femur black, the narrower curved basal part yellow, antero-dorsally with 2 long dark erected setae near the apex (in holotype broken off, only 2 sockets visible); tibia without apico-ventral tooth, black, the basal 1/6 and a broad annulus on the apical 1/2 yellow; tarsus blackish. Abdomen. Length ratio of tergites I, II, III and IV 1:4.2:2.5:1.5; tergites shiny black, tergite III yellow on anterior 1/3; pile of tergites short and adpressed, reddish and blackish; tergite I with 3 black, widely separated setae at lateral margin (in holotype only 2 visible); sternite IV ( Figs 9 A, B) mainly brown, the pile adpressed and pale, the strong setae black; sternite VI ( Fig. 9 A) with a long, narrow, straight process on anterior part and a conical tubercle on posterior part, black, with long, pale pile; sternite VII simple, black, with long pale pile; sternite VIII simple, black, with pale pile on anterior part, shorter than that on sternite VII. Genitalia, Figs 9 C–E. Note the strongly asymmetrical surstyli and superior lobes and the basomedial lobe on the surstylus. FEMALE. Unknown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m., 11.v.1934, R. Malaise ( SMNH).

Etymology. The name is Latin, index , forefinger, referring to the finger-like lobe on the superior lobe.

Discussion. Sphegina index is similar to S. carinata . Except for the characters mentioned in the key they differ as follows: 1) the two lateralmost of the enlarged setae on the left side of male sternite IV are ca. twice longer than the longest one of the more medial setae (in S. carinata ca. five times longer), 2) male superior lobe has an inconspicuous lobe baso-dorsally (pointed finger-like lobe) and 3) male superior lobe with a large flip-like lobe ventrally, partly covering a recurrent finger like lobe (small flip-like lobe in more dorsal position, far from a ventral straight finger-like lobe). For further discussion, see under S. carinata .

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 9. Sphegina (Asiosphegina) index sp. n. (holotype). A. Posterior part of abdomen, lateral 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.