Sphegina (Asiosphegina) clavigera, 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 : 55-58
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|Sphegina (Asiosphegina) clavigera|
Sphegina (Asiosphegina) clavigera sp. nov.
The specific epithet is from the Latin ‘ clavigera ’, meaning ‘bearing claws’ and referring to the two clawlike lobes on the male superior lobe.
VIETNAM • ♂; “NW VIETNAM: Tonkin / Hoang Lien N.P. 15 km / W Sa Pa c. 1900 m / 15–21.X.1999 Malaise traps / [leg] C. v. Achterberg; RMNH ‘99”; NBC.
VIETNAM: 1 ♀; same data as for holotype; NBC.
LENGTH. Body 7.2 mm, wing 6.3 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: 2.4; ratio length of ocellar triangle: length of frons 1: 2.3. 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, slightly pollinose, a narrow subtriangular area posterior of lunula non-pollinose and shiny; pile short, light yellow. Frons without antero-medial depression. Occiput black, light grey pollinose, light yellow pilose. Eye with an area of enlarged facets at anterior margin. Antenna with scape and pedicel black, basoflagellomere dark brown with black setae dorsally on scape and pedicel; basoflagellomere oval, ratio width: length 1: 1.5; arista long pilose, nearly 3.5 times as long as basoflagellomere.
THORAX. Pleuron entirely grey pollinose; scutum and pleuron with very short adpressed light yellow pile. Scutellum subtriangular, black, shiny medially, laterally weakly pollinose, with pile slightly longer than on scutum, with two closely set, long setae medially at posterior margin, ratio length of scutellum: length of seta 1: 2.0.
WING. Entirely microtrichose; hyaline, stigma yellowish, membrane brown infuscated at junction of veins R2+3 and R4+5, along veins bm-cu, r-m, M1, at the junction of veins M1 and R4+5 and at apical appendix of vein R2+3. Crossvein dm-cu meeting vein M perpendicularly and vein M1 meeting vein R4+5 perpendicularly. Apical part of vein R2+3 with short appendix, vein CuA1 slightly extended to vein dmcu.
LEGS. Pro- and mesoleg yellow, tarsomeres 4 and 5 black. Metaleg with coxa black, trochanter yellow; femur black with basal half yellow, slightly incrassate, ratio width: length 1: 4.8, dorso-basally slightly concave; tibia black and yellow biannulate, without apicoventral dens; tarsus entirely black, basitarsomere very thin, ratio width: length 1: 4.8.
ABDOMEN. Length ratio of terga I: II: III: IV 1: 3.0: 1.9: 1.3; ratio width at posterior margin: medial length of tergum II and III 1: 4.4 and 1: 1.1. Terga black, anterior ⅓ of tergum III with yellow fascia; pile pale, on terga short, laterally on terga I and II long; tergum I with 2 widely separated strong black setae at lateral margin; sternum III rectangular with concave posterior margin, ratio width: length 1: 2.3; sternum IV, Fig. 20B View Fig ; sterna VI, VII and VIII ( Fig. 20A View Fig ) with long yellow pile, sternum VII with two processes of which the more anterior one is conical with long light-brown setae at base and the more posterior one low crescent-shaped. Genitalia, Fig. 20 View Fig C–E: note the asymmetrical surstyli, the finger-like process basomedially on surstyli and the only slightly asymmetrical superior lobes.
Similar to the male except normal sexual dimorphism.
LENGTH. Body 7.3 mm, wing 6.4 mm.
HEAD. Ratio width of vertex at anterior ocellus: width of head 1: 3.6; ratio width of ocellar triangle: width of vertex 1: 2.5; ratio length of ocellar triangle: length of frons 1: 3.3. Mouth edge narrowly brown. Basoflagellomere oval, ratio width: length 1: 1.4, about 3.5 times as long as basoflagellomere.
THORAX. Scutellum with two closely set, long setae medially at posterior margin, ratio length of scutellum: length of seta 1: 2.0.
LEGS. Metafemur slightly incrassate, ratio width: length 1: 5.6, yellow on basal ½, basitarsomere very thin, ratio width: length 1: 4.6.
ABDOMEN. Length ratio of terga I: II: III: IV: V 1: 2.1: 1.6: 1.0: 0.6; ratio width at posterior margin: medial length of tergum II and III 1: 3.0 and 1: 0.9. Tergum I, Fig. 8D View Fig black; tergum II posterior ⅓ yellow; sternum III elongate, ratio width: length 1: 2.8; sternum IV trapezoid, ratio width: length 1: 1.0; sternum V rectangular, with crenelated posterior margin, ratio width: length 1: 1.2.
Distribution and biology
Collected together with Sphegina (Asiosphegina) index and S. (A.) malaisei in a Malaise trap near the Tram Ton Pass, the highest mountain pass in Vietnam (1900 m), near Fan Si Pan mountain. The Malaise trap had been set up in an area of montane forest disturbed by buffaloes grazing, containing muddy areas and small streams. Despite the cold and wet weather insects were still rather abundantly flying (C. van Achterberg, pers. comm).
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