Sphegina (Asiosphegina) hansoni Thompson, 1966

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 : 93-94

Sphegina (Asiosphegina) hansoni Thompson, 1966

Figs 38J , 41E , 42 , 52A

Sphegina hansoni Thompson, 1966: 42 . Type locality: Parewavir, Nepal (holotype, ♂, USNM).

Differential diagnosis

Sphegina (Asiosphegina) hansoni resembles other Sphegina with strongly asymmetrical male sternum IV posteriorly armed with strong black setae, but is easily distinguished by the characters given in the key. The carinate metatrochanter is a more unique character which it shares only with Sphegina (Asiosphegina) carinata , S. (A.) malaisei and S. (A.) ornata sp. nov. In the male genitalia, the almost symmetrical surstyli is a unique character within this group of species.

Material examined

Holotype

NEPAL • ♂; Sphegina hansoni : “Parewavir Nepal / elev. III. 26.1957 / leg. Edward I. Coher G. P. Joshi”; “ holotype / Sphegina / hansoni / Thompson ‘64” [faded red label]; genitalia on slide in Canada balsam, tergum IX and cerci lost; USNM.

Redescription

Male

LENGTH. Body 7.1 mm, wing 5.9 mm.

HEAD. Face in lateral view concave, very strongly projected antero-ventrally; frontal prominence strongly developed. Ratio width of vertex at anterior ocellus: width of head 1: 3.8; ratio width of ocellar triangle: width of vertex 1: 2.3; ratio length of ocellar triangle: length of frons 1: 3.3. Face black; light grey pollinose, long pilose along eye-margin. Hypostomal bridge black, long pale pilose. Gena and mouth edge black with large subtriangular non-pollinose shiny area. Frons and vertex black; grey pollinose, a narrow area posterior of lunula yellow, non-pollinose and shiny ( Fig. 38J ); pile short, light yellow. Frons with deep pit antero-medially and wide furrow medially. Occiput black, light grey pollinose, light yellow pilose. Eye without enlarged facets at anterior margin. Antenna with scape and pedicel brownyellow, basoflagellomere yellow, with black setae dorsally on scape and pedicel; basoflagellomere oval, ratio width: length 1: 1.3; arista long pilose, nearly 3.5 times as long as basoflagellomere.

THORAX. Colour dark brown to black, scutum with dense grey-brown pollinosity and pleuron with slight grey pollinosity, sub-shiny; scutum and pleuron with very short adpressed light yellow pile. Scutellum semicircular, black, slightly grey pollinose sub-shiny, with pile slightly longer than on scutum, with two widely set, very short setae medially at posterior margin, ratio length of scutellum: length of seta 1: 0.7.

WING. Entirely microtrichose; hyaline, stigma yellowish, membrane brown infuscated at junction of veins R 2+3 and R 4+5, along veins bm-cu, r-m and M 1. Crossvein dm-cu meeting vein M perpendicularly and vein M

1

meeting vein R

4+5

perpendicularly.

LEGS. Pro- and mesoleg yellow, tarsomeres 3–5 black. Metaleg, Fig. 52A , with coxa black, trochanter yellow with dark brown transverse carina; femur black with basal ¼ yellow, slightly incrassate, ratio width: length 1: 4.4; tibia black and yellow biannulate without apicoventral dens; tarsus entirely brownyellow to dark brown, basitarsomere thin, ratio width: length 1: 4.5.

ABDOMEN. Length ratio of terga I: II: III: IV 1: 4.2: 2.4: 1.5; ratio width at posterior margin: medial length of tergum II and III 1: 5.1 and 1: 1.0. Terga black, anterior ⅓ of tergum III with brown-yellow fascia; pile pale, on terga short, laterally on terga I and II long; tergum I with row of 3 strong black setae at lateral margin; sternum III rectangular, ratio width: length 1: 1.5; sternum IV, Fig. 42B ; sterna VI, VII and VIII with long yellow pile, sternum VII with elongate light yellow pilose finger-like tubercle anteriorly. Genitalia, Fig. 42F (the hypandrium is on the slide with the left side up and the right-side superior lobe is drawn by focusing the microscope to that side): note the almost symmetrical surstyli and the asymmetrical superior lobes.

Female

Unknown.

Figures

Fig. 38. Head, lateral view (C, K), dorsal view (A–B, D, F–J, L) and frontal view (E). A. Sphegina (Asiosphegina) farinosa sp. nov.,holotype, Ƌ, Sabah, Malaysia. B. S. (A.) fimbriata sp. nov., holotype, Ƌ, Thailand. C–D. S. (A.) forceps Hippa, van Steenis & Mutin, 2015, paratype, Ƌ, Myanmar. E. S. (A.) furva Hippa, van Steenis & Mutin, 2015, paratype, Ƌ, Myanmar. F. S. (A.) ghatsi, sp. nov., holotype, Ƌ, India. G. S. (A.) gigantea sp. nov., holotype, Ƌ, China. H. S. (A.) granditarsis sp. nov., paratype, Ƌ, Thailand. I. S. (A.) hamulata sp. nov., holotype, Ƌ, India. J. S. (A.) hansoni Thompson, 1966, holotype, Ƌ, Nepal. K–L. S. (A.) hauseri sp. nov., paratype, Ƌ, Nepal. Scale bars = 0.5 mm.

Fig. 41. Habitus, lateral view. A. Sphegina (Asiosphegina) gigantea sp. nov., holotype, Ƌ, China. B. S. (A.) gigas Hippa, van Steenis & Mutin, 2015, paratype, ♀, Myanmar. C. S. (A.) granditarsis sp. nov., paratype, Ƌ, Thailand. D. S. (A.) hamulata sp. nov., holotype, Ƌ, India. E. S. (A.) hansoni Thompson, 1966, holotype, Ƌ, Nepal, Malaysia. F. S. (A.) hauseri sp. nov., paratype, Ƌ, Nepal. Scale bars = 1.0 mm.

Fig. 42. Sphegina (Asiosphegina) hansoni Thompson, 1966, holotype, Ƌ. A. Posterior part of abdomen, left side lateral view. B. Sternum IV, ventral view. C–F. Genitalia. C. Left surstylus, lateral view. D. Right superior lobe, lateral view, focused in microscope from left side. E. Right surstylus, lateral view. F. Left superior lobe, lateral view. Scale bars = 0.5 mm.

Fig. 52. Metaleg, dorsal view (A) and anterior view (B–F). A. Sphegina (Asiosphegina) hansoni Thompson, 1966, holotype, Ƌ, Nepal. B. S. (A.) index Hippa, van Steenis & Mutin, 2015, ♀, Kambaiti. C. S. (A.) cf. inflata sp. nov., ♀, Philippines. D. S. (A.) inventum sp. nov., paratype, ♀, Sabah. E. S. (A.) javana de Meijere, 1914, paralectotype, Ƌ, Java. F. S. (A.) karnataka sp. nov., paratype, Ƌ, India. Scale bars = 0.5 mm.