Sphegina (Asiosphegina) lobulata, 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 : 118-121

Sphegina (Asiosphegina) lobulata sp. nov.

urn:lsid:zoobank.org:act:01493A30-4C65-46F3-AF5D-47CD4D81670C

Figs 47F , 56C , 57 A–G, 59B

Differential diagnosis

Sphegina (Asiosphegina) lobulata sp. nov. is similar to S. (A.) radula , S. (A.) raduloides and S. (A.) subradula . Except for the characters mentioned in the key, it is distinguished by having the dorsal lobe of male surstylus on both sides equally wide (wider on the left side in the other species) and by having the ventral lobe of the right side surstylus with notched posterior margin (even margin in the others). All the species mentioned resemble Sphegina (Asiosphegina) nigrapicula Huo, Ren & Zheng, 2007 , from China. The latter differs by having all the setae posteriorly on male tergum IV rather thin and those on the right side all short, shorter than on the left side.

Etymology

The specific epithet is from the Latin ‘ lobulata ’, meaning ‘having lobes’ and referring to the lobes on the male superior lobe.

Material examined

Holotype

VIETNAM • ♂; “Viet-Nam vi / Ha-noi / Strnad [sic], 1990”; ZFMK Dipt / QR code / 00011900”; ZFMK.

Paratypes

VIETNAM • 1 ♂; same data as for holotype; ZFMK • 9 ♂♂, 5 ♀♀; “ Vietnam / Vinh Phuc prov. Tam Dao / 21°27 ʹ 52 ″ N, 105°38 ʹ 46 ″ E 1.200 m / 19–22.VI.2014 hand collected / leg. M. Hauser & N. von Ellenrieder ”; CSCA • 6 ♂♂, 3 ♀♀; same data as for preceding; JSA • 1 ♀; “ Vietnam, Tam Dao / pr. Vinh Phu 1000 m / forest 10.11.1990 / leg. N. Nartshuk ”; “coll V. Mutin ”; VMK .

Description

Male

LENGTH. Body 6.9–7.3 mm, wing 4.4–5.1 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: 4.5–4.7; ratio width of ocellar triangle: width of vertex 1: 1.7–1.9; ratio length of ocellar triangle: length of frons 1: 2.8–3.0. 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, predominantly grey pollinose, a large more densely pollinose rectangular area posteriorly from lunula with antero-medial semi-circular non pollinose macula; pile short, light yellow. Frons with narrow medial furrow. Occiput black, light grey pollinose, light yellow pilose. Eye with enlarged facets at anterior margin. Antenna black with black setae dorsally on scape and pedicel; basoflagellomere elongate, ratio width: length 1: 1.9–2.2; arista long pilose, slightly more than 3 times as long as basoflagellomere.

THORAX. Colour black, weakly greyish pollinose, pleuron entirely more heavily grey pollinose; scutum and pleuron with very short adpressed light yellow pile. Scutellum semicircular, black, 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: 0.8.

WING. Entirely microtrichose; brown tinged, stigma yellowish. Crossvein dm-cu meeting vein M obliquely and vein M

1

meeting vein R

4+5

perpendicularly.

LEGS. Pro- and mesofemur and tibia black with only base and apex narrowly yellow or entirely yellow to dark yellow; pro- and mesotarsus with tarsomeres 3 and 4 black. Metaleg with coxa black and trochanter yellow; femur black with basal ¼ yellow or black and yellow biannulate, slightly incrassate, ratio width: length 1: 3.6–3.8, with basally 3 black setulae in the yellow part; tibia black and yellow biannulate with short but widely rounded apicoventral dens; tarsus entirely black, basitarsomere rather thin, ratio width: length 1: 3.7–3.9.

ABDOMEN. Length ratio of terga I: II: III: IV 1: 4.7–4.9: 2.0–2.2: 1.6–1.7; ratio width at posterior margin: medial length of tergum II and III 1: 6.0–6.1 and 1: 1.0–1.1. Terga black, anterior ⅓ of tergum III with yellow fascia; pile pale, on terga short, laterally on terga I and II long; tergum I, Fig. 47F with a horizontal row of 3 long, strong, black setae at lateral margin; sternum III elongate, subtriangular, ratio width: length 1: 3.2–3.3; sternum IV, Fig. 57 A–C; sternum VII anteriorly with wide but weak tubercle and posteriorly with low ridge like tubercle; sterna VI, VII and VIII with long yellow pile. Genitalia, Fig. 57 D–G: note the equally wide and almost symmetrical surstyli and the slightly asymmetrical superior lobes.

Female

Similar to male except for the usual sexual dimorphism.

LENGTH. Body 5.7–6.1 mm, wing 4.5–4.9 mm.

HEAD. Ratio width of vertex at anterior ocellus: width of head 1: 3.8–4.3; ratio width of ocellar triangle: width of vertex 1: 1.8–2.1; ratio length of ocellar triangle: length of frons 1: 2.0–2.3. Basoflagellomere oval, ratio width: length 1: 1.4–1.7; arista long pilose, about 2.5 times as long as basoflagellomere.

THORAX. Scutellum with two widely set, very short setae medially at posterior margin, ratio length of scutellum: length of seta 1: 0.8–0.9.

LEGS. Metafemur, ratio width: length 1: 3.9–4.3; metatarsus with basitarsomere thick, ratio width: length 1: 3.1–3.3.

ABDOMEN. Length ratio of terga I: II: III: IV: V 1: 3.5–3.9: 2.5–2.9: 2.0–2.4: 0.9–1.3; ratio width at posterior margin: medial length of tergum II and III 1: 2.9–3.3 and 1: 0.8–0.9. Tergum II predominantly dark yellow; anterior ⅓ of tergum III with orange-brown fascia; terga IV and V predominantly to entirely dark yellow; sternum III rectangular, ratio width: length 1: 2.8–3.2; sternum IV crescent-shaped with convex posterior margin, ratio width: length 1: 0.4–0.6; sternum V rectangular, ratio width: length 1: 0.7–0.8.

Remarks

The colouration of the legs shows a high degree of interspecific variation with extensively blackcoloured forms to predominantly yellow-coloured ones. The yellow-coloured specimens tend to have a yellow mouth edge, yellow basoflagellomere and yellow proepisternum and proepimeron. There are many intermediate specimens in which the yellow gradually shifts from dark yellow via brown and dark red-brown to black. All females and two males belong to the yellow form and no differences have been found in any other character including the male genitalia. The existence of intermediate specimens and the lack of differences in the genitalia indicates that all these specimens belong to one species. The holotype is an extensively black-coloured specimen.

Figures

Fig. 47. Tergum I, lateral view (A, C–D) and dorsal view (B, E–F). A. Sphegina (Asiosphegina) dentata sp. nov., paratype, Ƌ, Taiwan. B. S. (A.) distincta sp. nov., paratype, Ƌ, Vietnam. C. S. (A.) falcata Hippa, van Steenis & Mutin, 2015, holotype, Ƌ, Myanmar. D. S. (A.) farinosa sp. nov., holotype, Ƌ, Sabah, Malaysia. E. S. (A.) javana de Meijere, 1914, Paralectotype Ƌ, Java, Indonesia. F. S. (A.) lobulata sp. nov., paratype, Ƌ, Vietnam. Dotted line indicates unknown length of right sided setae, the right metaleg (erased in GIMP) obscured these setae. Scale bars = 0.5 mm,

Fig. 56. Habitus, lateral view. A. S. (A.) karnataka sp. nov., paratype, Ƌ, India.B. Sphegina (Asiosphegina) licina sp. nov., holotype, Ƌ, Thailand. C. S. (A.) lobulata sp. nov., paratype, Ƌ, Vietnam. D. S. (A.) lucida sp. nov., paratype, Ƌ, Vietnam. E. S. (A.) lucida sp. nov., paratype, ♀, Vietnam. F. S. (A.) malaisei Hippa, van Steenis & Mutin, 2015, paratype, Ƌ, Myanmar. Scale bars = 1.0 mm.

Fig. 57. Sphegina (Asiosphegina) lobulata sp. nov., holotype, Ƌ (A, D, E, G), paratype, Ƌ Tam Dao 1 (C, F) and paratype, Ƌ Tam Dao 2 (B). A–C. Sternum IV, ventral view. D. Left surstylus, lateral view. E. Left superior lobe with associated parts, lateral view. F. Right superior lobe with associated parts, lateral view. G. Genitalia, right side, lateral view. Scale bars = 0.5 mm.