Sphegina (Asiosphegina) adusta, 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

Sphegina (Asiosphegina) adusta sp. n.

Figs 34 A–D

MALE. Body length 8.3 mm, wing length 6.7 mm. Head. Face strongly concave, moderately projected anteroventrally; frontal prominence weakly developed (similar to Fig. 1J). Width of vertex at anterior ocellus:width of head 1:4.5; depth of occipital fossa less than 1/4 of the width of an eye in dorsal view. Width of face:width of head 1:3.7. Face blackish brown, medially slightly paler brown, faintly pale pollinose. Gena brown, faintly pale pollinose. Frons and vertex dull blackish brown; lunula paler brown; frons with a slight depression posterior to the frontal prominence; the pile brown. Occiput black, faintly pale pollinose. Antenna blackish; basoflagellomere as long as broad, semiquadrangular; arista pilose. Thorax. Colour blackish brown, faintly pale pollinose, postalar callus paler brown, the pile short, adpressed and brown; scutellum shiny dark brown, the margin slightly paler brown, the pile similar to that on the posterior part of scutum, at apical margin with two setae of which only the sockets are left in the single specimen. Wing. Slightly brownish, stigma brown. Legs. Pro- and mesoleg unicolorous dark brown, only the knees slightly paler. Metaleg: unicolorous dark brown; trochanter simple, tibia without an apico-ventral tooth. Abdomen. Length ratio of tergites I, II, III and IV 1:4.4:2.4:0.0. Tergites shiny dark brown, the pile brown, short, and adpressed, becoming longer and paler towards the lateral margin of tergite II; tergite I laterally with an oblique row of 5 pale setae laterally; sternite IV ( Fig. 34 A) brown, the pile pale; sternites VI–VIII simple, brown, the pile pale. Genitalia, Figs 34 B–D. Note the strongly asymmetrical surstyli. The superior lobes are symmetrical. FEMALE. Body length 8.6 mm, wing length 7.7 mm. Similar to male except for the normal sexual dimorphism. Length ratio of tergites I, II, III and IV 1:4.3:2.4:2.1; tergite II predominantly darkorange; tergite I laterally with an oblique row of 4 yellow setae; ratio of length:width of tergites III and IV 1:1.8 and 1:2.0; sternite IV broadly trapezoidal, brown; sternite V broadly rectangular, pale brown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 7000 ft., 5.v.1934, R. Malaise ( BMNH). PARATYPE. 1♀ with same data as holotype except: 2000 m, 19.iv. ( NBC).

Etymology. The name is Latin, adusta , tanned or brown, referring to the almost unicolorous dark-brown colour of the fly.

Discussion. Sphegina adusta is dissimilar to all other species described in this paper. Its large size, general dark-brown colouration and the characters appearing in the key unmistakably identify the species. The left side surstylus with a number of unusual sublobes is very distinctive. By having a large subtriangular lobe sinistrolaterally at the posterior margin of male sternite IV S. adusta recalls S. atricolor and S. furva but it lacks a tranverse crest at the base of this lobe characteristic of these species. For more discussion, see under S. atricolor .

Figures

FIGURE 34. Sphegina (Asiosphegina) adusta sp. n. (holotype). A. Posterior part of sternite IV, ventral view. B. Genitalia, lateral view. C. Aedeagus, lateral view. D. Left surstylus, lateral view. Scale 0.5 mm.