Sphegina (Asiosphegina) atrimanus, 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 : 39-43

Sphegina (Asiosphegina) atrimanus sp. nov.

urn:lsid:zoobank.org:act:5DC1DA56-B25E-42C2-B4F3-969E9FCC830B

Figs 11B , 12 , 61A

Differential diagnosis

Sphegina (Asiosphegina) atrimanus sp. nov. is similar to S. (A.) granditarsis sp. nov., S. (A.) incretonigra sp. nov., S. (A.) nasuta , S. (A.) nigrotarsata sp. nov. and S. (A.) orientalis but is distinguished by the characters mentioned in the key. In male genitalia these species differ from other Sphegina (Asiosphegina) known to us by having an area of very long setae on the cercus and by having small setae on the surstylar apodeme and the membrane between the apodeme and the ventral margin of tergum IX. Sphegina (A.) atrimanus sp. nov. differs from S. (A.) granditarsis sp. nov., S. (A.) nigrotarsata sp. nov. and S. (A.) orientalis by having the angle between dorsal and ventral lobe of the surstylus as a right angle (acute in the others); by having the apex of its ventral lobe long, extending much more ventrally than the posterior part of the surstylar apodeme (both approximately at the same level); and by having the cercus enlarged. Sphegina (A.) atrimanus sp. nov. differs from S. (A.) nasuta by having the dorsal lobe of surstylus slightly angled and dilated on the apical part (evenly curved and evenly tapering towards the apex). The genitalia of S. (A.) atrimanus sp. nov. and S. (A.) incretonigra sp. nov. are almost identical, the former having the apical part of the surstylus, especially on the left side, and the superior lobe wider ( Figs 12 B–C and 46B–C).

Etymology

The specific epithet is from the Latin ‘ atrimanus ’, meaning ‘black-hand’, referring to the predominantly black protarsus. The name is a noun in apposition.

Material examined

Holotype

VIETNAM • ♂; “ Viet Nam : Mt. Lang / Bian 1500–2000 / 19.V–8.VI.1961 ”; “ N. R. Spencer / Collector / Bishop”; BPBM.

Description

Male

LENGTH. Body 6.2 mm, wing 5.2 mm.

HEAD. Face in lateral view concave, weakly projected antero-ventrally; frontal prominence strongly developed. Ratio width of vertex at anterior ocellus: width of head 1: 5.3; ratio width of ocellar triangle: width of vertex 1: 1.4; ratio length of ocellar triangle: length of frons 1: 1.9. Face black, ventral half yellow; light grey pollinose, long pilose along eye-margin. Hypostomal bridge yellow, long pale pilose. Gena and mouth edge yellow with large subtriangular non-pollinose shiny area. Frons and vertex black; frons largely shiny, non-pollinose except for subtriangular grey pollinose macula at eye-margin; pile short, light yellow. Frons with wide and deep pit antero-medially. Occiput black, light grey pollinose, light yellow pilose. Eye without enlarged facets at anterior margin. Antenna with scape dark brown, pedicel and basoflagellomere dark yellow with black setae dorsally on scape and pedicel; basoflagellomere oval, ratio width: length 1: 1.6; arista short pilose, about 3 times as long as basoflagellomere.

THORAX. Colour dark brown to black, postpronotum and medial part of pleuron yellow; weakly greyish pollinose, pleuron more heavily 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, very short setae medially at posterior margin, ratio length of scutellum: length of seta 1: 0.7, but possibly apices of setae broken off.

WING. Partly destroyed on both sides. Entirely microtrichose; hyaline, stigma yellowish, membrane brown infuscated along veins bm-cu, M 1, at the junction of veins M 1 and R 4+5. Crossvein dm-cu meeting vein M perpendicularly and vein M 1 meeting vein R 4+5 perpendicularly.

LEGS. Pro- and mesoleg yellow, protarsus with tarsomere 1 on basal half yellow, on apical half black, tarsomeres 2–5 black and mesotarsus with tarsomeres 4 and 5 dark brown to black; protarsus enlarged and flattened, ratio apical width of tibia: width of tarsomere 2 1: 1.6. Metaleg with coxa black, trochanter yellow; femur black and yellow biannulate, slightly incrassate and club shaped, ratio width: length 1:

4.7; tibia black and yellow biannulate, without apicoventral dens; tarsus entirely black, basitarsomere very thick, ratio width: length 1: 2.9.

ABDOMEN. Length ratio of terga I: II: III: IV 1: 4.1: 2.7: 2.5; ratio width at posterior margin: medial length of tergum II and III 1: 5.0 and 1: 1.5. Terga black, tergum II with sub-anterior light-brown fascia, 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 yellow setae at lateral margin; sternum III elongate, ratio width: length 1: 4.1; sternum IV, Fig. 12A ; sterna VI, VII and VIII simple, with long yellow pile. Genitalia, Fig. 12 B–D: note the area of long setose pile deviating from other pilosity on cercus and the small setae on postgonal apodeme and the membrane between the apodeme and ventral margin of tergum IX.

Female

Unknown.

Distribution and biology

Collected together with Sphegina (Asiosphegina) lucida sp. nov., S. (A.) nigrotarsata sp. nov., S. (A.) spenceri sp. nov. and S. (A.) vietnamensis sp. nov.

Remarks

Even if the genitalia of Sphegina (Asiosphegina) atrimanus sp. nov. are largely similar to those of S. (A.) incretonigra sp. nov., we are sure they belong to different species based on the difference in the characters of protarsus which is in the same magnitude between these two species and that of S. (A.) granditarsis sp. nov. and S. (A.) nigrotarsata sp. nov.

Figures

Fig. 11. Habitus, lateral view. A. Sphegina (Asiosphegina) atricolor Hippa, van Steenis & Mutin, 2015, paratype, Ƌ, Myanmar. B. S. (A.) atrimanus sp. nov., holotype, Ƌ, Vietnam. C. S. (A.) bidens Hippa, van Steenis & Mutin, 2015, paratype, ♀, Myanmar. D. S. (A.) bifida sp. nov., holotype, Ƌ. E. S. (A.) bilobata Hippa, van Steenis & Mutin, 2015, paratype, Ƌ, Myanmar. Scale bars = 1.0 mm.

Fig. 12. Sphegina (Asiosphegina) atrimanus sp. nov., holotype, Ƌ. A. Sternum IV, ventral view. B. Left surstylus, lateral view. C. Left superior lobe, lateral view. D. Genitalia, right side, lateral view. Scale bars = 0.5 mm.

Fig. 61. Protarsus, dorsal view. A. Sphegina (Asiosphegina) atrimanus sp. nov., holotype, Ƌ, Vietnam. B. S. (A.) granditarsis sp. nov., holotype, Ƌ, China. C. S. (A.) incretonigra sp. nov., holotype, Ƌ, Vietnam. D. S. (A.) nigrotarsata sp. nov., paratype, Ƌ, Vietnam. E. S. (A.) orientalis Kertész, 1914, Ƌ, Taiwan. F. S. (A.) plautus sp. nov., holotype, Ƌ, China. Scale bars 0.5 mm.