Sphegina (Asiosphegina) vietnamensis, Steenis & Hippa & Mutin, 2018

Steenis, Jeroen Van, Hippa, Heikki & Mutin, Valeri A., 2018, Revision of the Oriental species of the genus Sphegina Meigen, 1822 (Diptera: Syrphidae), European Journal of Taxonomy 489, pp. 1-198 : 190-192

Sphegina (Asiosphegina) vietnamensis sp. nov.

urn:lsid:zoobank.org:act:0930F518-0F49-4608-9B37-770DAAB6320A

Figs 88L , 93E , 97E , 98

Differential diagnosis

Similar to Sphegina (Asiosphegina) bracon sp. nov. and S. (A.) furcillata sp. nov. For distinguishing characters, see under S. (A.) bracon sp. nov.

Etymology

The specific epithet is from the Latin ‘ vietnamensis ’, meaning ‘of Vietnam’ and referring to the type locality, Vietnam.

Material examined

Holotype

VIETNAM • ♂; “ Viet Nam : Fyan / 900–1000 m / 11.VII–9.VIII.’61”; “ N.R. Spencer / Collector / Bishop”; BPBM.

Paratypes

VIETNAM • 5 ♂♂; same data as for holotype; BPBM • 4 ♂♂; same data as for holotype; JSA • 1 ♂; “ Viet Nam : Mt. Lang / Bian 1500–2000 / 19.V–8.VI.1961 ”; “ N. R. Spencer / Collector / Bishop”; BPBM • 1 ♂; “ Viet Nam : Dalat / 6km S. 1400–1500 m / 9.VI–7.VII.1961 ”; “ N. R. Spencer / Collector; / Bishop”; BPBM .

Description

Male

LENGTH. Body 6.3–7.2 mm, wing 4.2–5.1 mm

HEAD. Face in lateral view concave, weakly projected antero-ventrally; frontal prominence very weakly developed. Ratio width of vertex at anterior ocellus: width of head 1: 4.4–4.8; ratio width of ocellar triangle: width of vertex 1: 1.7–1.9; ratio length of ocellar triangle: length of frons 1: 2.4–2.9. Face black, ventral half brown-yellow, light grey pollinose, long pilose along eye-margin. Hypostomal bridge brown-yellow, long pale pilose. Gena and mouth edge yellow, pale pollinose with large subtriangular non-pollinose shiny area. Frons and vertex black, predominantly grey pollinose, a semi-circular area posterior of lunula non-pollinose and shiny ( Fig. 88L ); pile short, light yellow. Frons with deep medial furrow. Occiput black, light grey pollinose, light yellow pilose. Eye with an area of enlarged facets at anterior margin. Antenna yellow to brown-yellow with black setae dorsally on scape and pedicel; basoflagellomere oval, ratio width: length 1: 1.2–1.6; arista pilose, about 3 times as long as basoflagellomere.

THORAX. Colour dark brown to black, weakly greyish pollinose; postpronotum and dorso-medial part of anepisternum and anepimeron yellow, pleuron entirely more heavily grey pollinose; scutum and pleuron with very short adpressed light yellow pile. Scutellum semicircular with concave lateral margin, black, shiny, with pile slightly longer than on scutum, with two widely set short setae medially at posterior margin, ratio length of scutellum: length of seta 1: 0.9–1.1.

WING. Entirely microtrichose; hyaline, stigma yellowish. Crossvein dm-cu meeting vein M obliquely and vein M 1 meeting vein R 4+5 perpendicularly.

LEGS. Pro- and mesoleg yellow, tarsomeres 4–5 black. Metaleg with coxa black, trochanter yellow; femur black and yellow biannulate, slightly incrassate, ratio width: length 1: 3.8–4.1; tibia black and yellow biannulate, with weak and short apicoventral dens; tarsus black, in some specimens tarsomeres 2 and 3 dark brown, basitarsomere thin, ratio width: length 1: 3.9–4.4.

ABDOMEN. Length ratio of terga I: II: III: IV 1: 4.8–5.7: 2.1–2.7: 1.8–2.1; ratio width at posterior margin: medial length of tergum II and III 1: 3.9–4.2 and 1: 0.8–0.9. Terga black, anterior ⅓ –½ of tergum III with yellow fascia and posterior 1/5 of tergum IV with brown-yellow fascia; pile pale, on terga short, laterally on terga I and II long; tergum I with 2–3 strong dark brown to black setae at lateral margin; sternum III squarish to rectangular, ratio width: length 1: 1.5–2.1; sternum IV, Fig. 98A ; sterna VI, VII and VIII with long yellow pile, sternum VII with a large rounded yellow pilose widely conical processes with a narrower sharp medial projection. Genitalia, Fig. 98 C–G: note the asymmetrical surstyli, bifid ventral lobe of right surstylus and the slightly asymmetrical superior lobes.

Female

Not separable from female of Sphegina (Asiosphegina) bracon sp. nov. and S. (A.) furcillata sp. nov.

Figures

Fig. 88. Head. lateral view (C, E, F, J) and dorsal view (A–B, D, G–I, K–L). A. Sphegina (Asiosphegina) spathigera sp. nov., holotype, Ƌ, Philippines. B–C. S. (A.) spenceri sp. nov., paratype, Ƌ, Vietnam. D–E. S. (A.) strigillata sp. nov., holotype, Ƌ, Vietnam. F. S. (A.) tricoloripes, Brunetti, 1915, ♀, India. G. S. (A.) tricoloripes, Ƌ, India. H. S. (A.) umbrosa sp. nov., holotype, Ƌ, China. I. S. (A.) varidissima Shiraki, 1930, Ƌ, Taiwan. J. S. (A.) varidissima, ♀, Taiwan. K. S. (A.) verrucosa sp. nov., paratype, Ƌ, Vietnam. L. S. (A.) vietnamensis sp. nov., paratype, Ƌ, Vietnam. Scale bars = 0.5 mm.

Fig. 93. Habitus, lateral view. A. Sphegina (Asiosphegina) tricoloripes Brunetti, 1915, Ƌ, India. B. S. (A.) umbrosa sp. nov., holotype, Ƌ, China. C. S. (A.) varidissima Shiraki, 1930, Ƌ, Taiwan, yellow form. D. S. (A.) verrucosa sp. nov., paratype, Ƌ, Vietnam. E. S. (A.) vietnamensis sp. nov., paratype, Ƌ, Vietnam. Scale bars = 1.0 mm.

Fig. 97. Habitus, dorsal view. A. Sphegina (Asiosphegina) umbrosa sp. nov., holotype, Ƌ, China. B. S. (A.) varidissima Shiraki, 1930, Ƌ, Taiwan. C. S. (A.) varidissima, ♀, Taiwan, yellow form. D. S. (A.) verrucosa sp. nov., paratype, Ƌ, Vietnam. E. S. (A.) vietnamensis sp. nov., paratype, Ƌ, Vietnam. Scale bars = 1.0 mm.

Fig. 98. Sphegina (Asiosphegina) vietnamensis sp. nov., holotype, Ƌ (A–E), paratype 1 (F) and paratype 2 (G). A. Sternum IV, ventral view. B. Sternum VII, ventral view. C. Left surstylus, lateral view. D. Left superior lobe with associated parts, lateral view. E. Genitalia, right side, lateral view. F–G. Left and right superior lobe, lateral view. Scale bars = 0.5 mm.