Sphegina (Asiosphegina) atricolor, 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 : 55-57

Sphegina (Asiosphegina) atricolor sp. n.

Figs 1F, I, 35A–E

MALE. Body length 6.2–7.5 mm, wing length 5.2–6.5 mm. Head (Figs 1F, I). Face strongly concave and weakly projected antero-ventrally; frontal prominence weakly developed. Width of vertex at anterior ocellus less than 1/4 of the width of head [1:4.4]; depth of occipital fossa ca. 1/6 of the width of an eye in dorsal view. Width of face:width of head 1:4.4. Face black, mostly densely pale pollinose but rather weakly medio-ventrally. Gena shiny brown or yellow. Frons and vertex dull black, densely pollinose behind frontal prominence; lunula shiny brown; the pile pale, erect and short. Occiput dull black. Antenna dark brown, basoflagellomere oval; arista with short pile. Eye with an area of enlarged facets at anterior margin. Thorax. Colour black, densely pale pollinose; scutum with adpressed pale pile; scutellum semicircular, ratio of length:width 1:2.3, semi-shiny dorsally, pile pale, with a pair of long reddish rather widely separated setae at apical margin. Wing. Hyaline, stigma brownish. Legs. Proleg: yellow; trochanter yellow; femur mainly brownish, base and apex yellow; tibia yellowish, usually brownish medially; tarsus yellow, tarsomeres 4 and 5 black. Mesoleg: coxa yellow; trochanter yellow, simple; femur brown, basal 1/5 and apical 1/6 yellowish; tibia yellow, more or less developed brownish annulus on apical 1/2; tarsus yellow, tarsomeres 4 and 5 black. Metaleg: coxa brown; trochanter as rule yellow, simple; femur blackish, extreme base yellow; tibia without apico-ventral tooth, yellow, apical 1/5 dark brown and an obscure dark annulus medially; tarsus dark brown. Abdomen. Length ratio of tergites I, II, III and IV 1:3.2:1.6:1.2. Colour of tergites black, anterior 1/2 of tergite III reddish, posterior margin of fascia unclear, pile pale, short and adpressed, becoming longer laterally; tergite I with an oblique row of 4–5 strong yellow setae laterally; tergites III and IV strongly asymmetric, posterior margin skewed to the right; sternite IV ( Figs 35 A, B) black or brown, with fine pale pile, note the transverse crest at base of the posterior lobe, sternite VI ( Fig. 35 A) simple, black, with an area of long pale pile; sternites VII and VIII black, with pale pile. Genitalia, Figs 35 C–E. Note the strongly asymmetrical surstyli, the only slightly asymmetrical superior lobes, the strongly asymmetrical postero-ventral part of sternite IX, the elongated tergite IX and the narrow cercus. FEMALE. Unknown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 2000 m, 18.v.1934, R. Malaise ( SMNH). PARATYPES. 1♂ with same data as holotype except 8000 ft., 12.v. ( BMNH); 1♂ with same data except 7000 ft., 12.v. ( SMNH); 2♂ with same data except 7000 ft., 14.v. ( SMNH, NBC); 1♂ with same data except 7000 ft., 16.v. ( SMNH); 1♂ with same data except 7000 ft., 2.vi. ( SMNH); 1♂ with same data except 7000 ft., 9.vi. ( NBC).

Etymology. The name is Latin, atricolor , black, referring to the general dark colour of the fly.

Discussion. Sphegina atricolor is similar to S. furva and there are scarcely more non-genitalic characters available to distinguish them than those given in the key. In the male genitalia S. atricolor has tergite IX shorter than S. furva and the dorsal lobe of right side surstylus is much shorter, shorter than the medial lobe (between the dorsal and ventral lobes) (in S. furva much longer than the medial lobe) and on the left side surstylus the two lobes at the dorsal margin are much lower than in S. furva . Both species are also similar to S. adusta . For further discussion, see under the latter.

Sphegina atricolor and S. furva resemble a number of Oriental and east Palaearctic species by the large subtriangular lobe posteriorly on the left side of male sternite IV. In the Oriental region and in the transition zone between the Oriental and Palaearctic region these are: S. javana de Meijere, 1914, S. tricoloripes Brunetti, 1915 , S. micangensis Huo, Ren & Zheng, 2007 and S. univittata Huo, Ren & Zheng, 2007 and in the eastern part of the Palaearctic region S. elongata Shiraki & Edashige, 1953 , S. freyana Stackelberg, 1953 , S. grunini Stackelberg, 1953 , S. amamiensis Shiraki, 1968 , S. fasciata Shiraki, 1968 , S. thoraciaca Shiraki, 1968 and S. anatolii Mutin, 1998b ). From these S. atricolor and S. furva are distinguished by having a tranverse crest subbasally on the abovementioned lobe on sternite IV. Further, they differ e.g. by the following characters: scutum at least partly shiny with pollinose vittae in S. tricoloripes , S. amamiensis , S. elongata , S. fasciata , and S. thoraciaca (entirely pollinose in S. atricolor and S. furva ); katepisternum partly shiny in S. freyana , S. grunini and S. anatolii (entirely pollinose in S. atricolor and S. furva ); metafemur dark and pale annulate in S. javana and S. univittata (not annulated in S. atricolor and S. furva ); gena black in S. micangensis , S. tricoloripes , and S. amamiensis (brown to yellow in S. atricolor and S. furva ); tergite III with subbasal fascia in S. micangensis (with basal fascia in S. atricolor and S. furva ).

In the Kambaiti material there is a third species closely similar to Sphegina atricolor and S. furva , represented by a single male. Its genitalia are lost and we leave it undescribed.

Figures

FIGURE 35. Sphegina (Asiosphegina) atricolor sp. n. (A, B paratype, C, D, E holotype). A. Posterior part of abdomen, lateral view. B. Posterior part of sternite IV, ventral view. C. Genitalia, lateral view. D. Left surstylus, lateral view. E. Left superior lobe, lateral view. Scale 0.5 mm.