Sphegina (Asiosphegina) achaeta, 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 : 58-59

Sphegina (Asiosphegina) achaeta sp. n.

Figs 37 A–E

MALE. Body length 7.0 mm, wing length 5.9 mm. Head. Face strongly concave, weakly projected anteroventrally; frontal prominence weakly developed (similar to Fig. 1F). Width of vertex at anterior ocellus:width of head 1:4.5, depth of occipital concavity ca. 1/5 of the width of an eye in dorsal view. Width of face:width of head 1:4.3. Face dark brown, pale pollinose. Gena shiny brown. Frons and vertex black, densely pale pollinose; lunula shiny brownish; the pile short, erect and pale. Occiput dull black. Eye with an area of enlarged facets at anterior margin alongside face. Antenna brown; basoflagellomere semicircular; arista pilose. Thorax. Colour black, pale pollinose; scutum with short, adpressed reddish pile; scutellum semicircular, the pile similar to posterior part of scutum, a pair of convergent long pale setae at apical margin. Wing. Hyaline, stigma brownish. Legs. Proleg mainly yellow; femur yellow with wide, near 1/2 of femur length, apical brownish annulus; apical 1/2 of tibia diffusely brownish; tarsus yellowish, tarsomeres 4 and 5 lost in the single specimen. Mesoleg lost. Metaleg: coxa brown; trochanter brown, simple; femur brown with basal 1/4 yellow; tibia without apico-ventral tooth, brown with the basal 1/4 and an annulus on apical 1/2 yellow; tarsus dark brown. Abdomen. Length ratio of tergites I, II, III and IV 1:3.0:2.0:1.9. Tergites shiny black, tergite III with a yellow fascia on the anterior 1/2, the pile of tergites adpressed and pale, becoming longer towards the lateral margin; tergite I laterally with vertical row of 5 long, thin, pale setae which are only weakly differentiated from the other lateral vestiture; sternite IV ( Fig. 37 B) with a lobelike part posteriorly on the left side, brown, the pile pale; sternites VI–VIII simple, black, the pile pale. Genitalia, Figs 37 A, C–E. Note that the surstyli and the superior lobes are nearly symmetrical. FEMALE. Unknown.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 7000 ft, 14.v.1934, R. Malaise ( SMNH).

Etymology. The name is derived and Latinized from Greek words a, without, and chaite, long hair, referring to the lack of strong setae laterally on tergite I.

Discussion. In Sphegina achaeta the transverse postero-lateral row of 4–5 setae on abdominal tergite I differs from other species having this structure by having the setae weak, not much deviating from the other vestiture and in that the row is almost transverse, scarcely oblique. In its general appearance S. achaeta resembles S. adusta , S. atricolor and S. furva but is not especially similar to any of them and is easily distinguished by the characters given in the key. The male genitalia recall S. pollex and S. culex , especially in the superior lobe which posteriorly is widened both dorsally and ventrally. S. achaeta differs by having the posterodorsal corner acute. The surstylus of S. achaeta differs from both by having it much broader, from S. pollex also by lacking a subbasal dorsal thumb-like lobe. S. achaeta is similar to S. japonica Shiraki & Edashige, 1953 by the chaetotaxy of tergite I but differs by normal metatibia (in S. japonica apically strongly carinate), asymmetrical sternite IV (in S. japonica symmetrical), and the normal-sized apically rounded cerci (in S. japonica very large and triangular).

Figures

FIGURE 37. Sphegina (Asiosphegina) achaeta sp. n. (holotype). A. Right superior lobe and aedeagus, lateral view. B. Sternite IV, ventral view. C. Genitalia, lateral view. D. Left surstylus, lateral view. E. Left superior lobe, lateral view. Scale 0.5 mm.