Sphegina (Asiosphegina) parvula, 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 : 50-51

Sphegina (Asiosphegina) parvula sp. n.

Figs 4 E, G, 31A–C

MALE. Body length 4.4–4.5 mm, wing length 3.9–4.1 mm. Head Face strongly concave and weakly projected antero-ventrally; frontal prominence very weakly developed (similar to Fig. 1E). Width of vertex at anterior ocellus:width of head 1:3.2; depth of occipital concavity ca. 1/7 of the width of an eye in dorsal view. Width of face:width of head 1:3.8. Face brown, becoming ventrally paler brownish; pale pollinose, denser dorsally. Gena shiny brownish. Frons and vertex black; lunula brownish; frontal prominence shiny dark brown, the more posterior parts pale pollinose with a weak lateral macula of more dense pollinosity above the frontal prominence; the pile very short, rare, erect and pale. Occiput dull black. Eye with a large area of enlarged facets at anterior margin. Antenna brown, scapus and pedicellus paler than the basoflagellomere; basoflagellomere oval; arista nonpilose. Thorax. Colour black, faintly pale pollinose, the pile scattered, pale, short, almost invisible dorsally; scutellum semicircular, ratio of length:width 1:2.4, shiny, with a pair of thin, shorter than length of scutellum, pale setae at apical margin. Wing. Hyaline, stigma yellowish. Legs. Pro- and mesoleg yellow, tarsomeres 4 and 5 black.

Metaleg: coxa brown; trochanter simple, yellow; femur yellow, the apex and a wide annulus on the basal 1/2 brown; tibia without apico-ventral tooth, yellowish, the apical part and an annulus on the basal 1/2 brown; tarsus brown. Abdomen ( Fig. 4 G). Length ratio of tergites I, II, III and IV 1:3.1:1.5:1.5. Tergites shiny brown, tergite III with a yellow fascia on the anterior 1/2, sometimes more or less darkened along anterior margin, the pile of tergites pale, short, adpressed, becoming longer towards the lateral margin; tergite I ( Fig. 4 E) with an oblique row of 3–4 pale setae laterally; sternite IV ( Fig. 31 C) brownish, the posterior margin together with lobe paler yellowish, the pile pale; sternites VI–VIII black, the pile short and pale. Genitalia, Figs 31 A, B. Note the nearly symmetrical surstyli and the enlarged cercus. The superior lobes are symmetrical. Sternite IX is ventrally asymmetrical. FEMALE. Unknown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m, 19.iv.1934, R. Malaise ( SMNH). PARATYPES. 1♂ with same as holotype data ( NBC); 1♂ with same data except: 7000 ft., 27.iv. ( SMNH); 1♂ with same data except 7000 ft., 16. v. and Sphegina asciiformis Brun , det. v. Doesburg ( SMNH); 1♂ with same data except 7000 ft., 18. v. and Sphegina asciiformis Brun , det. v. Doesburg ( NBC).

Etymology. The name is Latin, parvula , very small, referring to the small size of the fly.

Discussion. Sphegina parvula is similar to S. pusilla and S. minuta and it may be difficult to distinguish between them without reference to male sternite IV and genitalia (see table 1). In S. parvula the lobe posteriorly on the male sternite IV is remarkably large and immediately distinguishes it from the other two species. In S. parvula the superior lobe has a third lobe between the dorsal and ventral lobes (lacking in S. minuta ), the mentioned third lobe has a shallow notch on margin (deep notch in S. pusilla ), the dorsal lobe of the left side surstylus has a small subapical medio-dorsal sublobe (very large sublobe in dorsal position in S. minuta , no sublobe at all in S. pusilla ). See also under S. sinesmila . Sphegina asciiformis Brunetti, 1915 which we only know on the basis of its description ( Brunetti 1915) resembles all of the mentioned species. Only the female of S. asiiformis is known, so maybe one of the 3 here described species is conspecific. S. potanini Stackelberg, 1953 and S. taibaishanensis Huo & Ren, 2006 are similar to S. parvula and S. pusilla by having reminiscent three-lobed surstylus and very similar superior lobe. They differ by having the medial lobe of surstylus narrow, as narrow as the dorsal and ventral lobes and by having their cercus greatly enlarged.

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 31. Sphegina (Asiosphegina) parvula sp. n. (holotype). A. Genitalia, lateral view. B. Left surstylus, lateral view. C. Posterior part of sternite IV, ventral view. Scale 0.5 mm.