Sphegina (Sphegina) angustata, 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 : 20-22

Sphegina (Sphegina) angustata sp. nov.

urn:lsid:zoobank.org:act:94A6F831-FFFF-49E3-BF04-C13C309E0B48

Figs 2 A–B, 3B–C, 4, 19B

Differential diagnosis

Similar to Sphegina (Sphegina) abbreviata sp. nov. For distinguishing characters, see under that species.

Etymology

The specific epithet is Latin ‘ angustata ’, meaning ‘narrowed’, referring to the unusually narrow abdomen.

Type material

Holotype

NEPAL • ♂; “ 27°58 ʹ N, 85°00 ʹ E / Mal. Tr. 1, 11.100’ [feet] / 29 June 1967 / Can. Nepal Exped.”; “ CNC DIPTERA / # 143315”; CNC.

Paratypes

NEPAL • 1 ♂; same data as for holotype; “ 19 June 1967 ”; JSA • 1 ♀; same data as for holotype; “ 3– 5 June 1967 ”; CNC • 1 ♀; same data as for holotype; “ 24 June 1967 ”; JSA • 1 ♀; same data as for holotype; “ 27 June 1967 ”; CNC .

Description

Male

LENGTH. Body 5.2–5.4 mm, wing 4.9–5.2 mm.

HEAD. Face in lateral view, Fig. 3C , concave, very strongly projected antero-ventrally; frontal prominence very strongly developed. Ratio width of vertex at anterior ocellus: width of head 1: 2.7–3.0; ratio width of ocellar triangle: width of vertex 1: 2.4–2.6; ratio length of ocellar triangle: length of frons 1: 2.5–2.8. Face dull dark brown, ventral half light-brown to yellow, pale pollinose, long pilose along eye-margin. Hypostomal bridge light-brown, long pale pilose. Gena and mouth edge yellow, pale pollinose with large subtriangular non-pollinose shiny area. Frons and vertex dark brown, predominantly grey pollinose, a subtriangular area posterior of lunula non-pollinose and shiny; pile short, light yellow brown. Frons with deep antero-medial pit and wide medial furrow. Occiput brown, light grey pollinose, light yellow pilose. Eye without enlarged facets at anterior margin. Antenna dark brown, with black setae dorsally on scape and pedicel; basoflagellomere oval, ratio width: length 1: 1.1–1.3; arista pilose, short and relatively thick, about 2.0–2.5 times as long as basoflagellomere.

THORAX. Colour dark brown, weakly greyish pollinose; postpronotum yellow to light-brown; scutum and pleuron with very short adpressed pale-brown pile. Scutellum subtriangular, dark brown, grey pollinose, 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. Proleg brown to brown-yellow, tarsomeres 3–4 dark brown to black. Mesofemur yellow with apical ⅔ dark brown; mesotibia yellow with basal ¾ dark brown; mesotarsus with tarsomeres 2–5 dark brown. Metaleg dark brown with yellow; femur dark brown on basal 2/5, weakly incrassate, ratio width: length 1: 4.2–4.6; tibia black and yellow biannulate, club shaped, without apicoventral dens; basitarsomere thin, ratio width: length 1: 3.9–4.2.

ABDOMEN. Length ratio of terga I: II: III: IV 1: 3.4–3.6: 2.7–3.0: 2.2–2.5; ratio width at posterior margin: medial length of tergum II and III 1: 3.4–3.8 and 1: 2.1–2.4. Terga dark brown; pile mixed dark brown to light-brown, short, laterally on terga I and II long; tergum I with only normal pile; sternum I elongate oval, ratio width: length 1: 1.9–2.1; sterna II–III not sclerotized; sternum IV, Fig. 4A ; sterna VI, VII and

VIII with long yellow pile. Genitalia, Fig. 4 B–D: note the almost symmetrical surstyli and symmetrical superior lobes.

Female

Similar to the male except normal sexual dimorphism.

LENGTH. Body 4.8–5.2 mm, wing 5.0– 5.5 mm.

HEAD. Ratio width of vertex at anterior ocellus: width of head 1: 3.2–3.4; ratio width of ocellar triangle: width of vertex 1: 2.1–2.4; ratio length of ocellar triangle: length of frons 1: 2.1–2.5 ( Fig. 3B ). Basoflagellomere round to slightly oval, ratio width: length 1: 1.0–1.2; arista pilose, short and relatively thick, about 2.5 times as long as basoflagellomere.

THORAX. Scutellum with two closely set, short setae medially at posterior margin, ratio length of scutellum: length of seta 1: 0.9–1.1.

LEGS. Metaleg, Fig. 19B , with femur slender, only very slightly incrassate, ratio width: length 1: 6.1–7.4, basitarsomere thin, ratio width: length 1: 4.2–4.6.

ABDOMEN. Length ratio of terga I: II: III: IV: V 1: 4.1–4.5: 3.8–4.2: 3.4–3.7: 1.0–1.3; ratio width at posterior margin: medial length of tergum II and III 1: 1.1–1.4 and 1: 0.5–0.7. Sternum I oval, ratio width: length 1: 0.6–0.8; sternum II oval, ratio width: length 1: 1.7–2.1; sternum III rectangular, ratio width: length 1: 1.2–1.6; sternum IV squarish, ratio width: length 1: 0.9–1.2; sternum V trapezoidal, posterior margin short, ratio width: length 1: 0.5–0.7.

Figures

Fig. 2. Habitus, lateral view. A. Sphegina (Sphegina) angustata sp. nov., paratype, Ƌ, Nepal. B. S. (S.) angustata sp. nov., paratype, ♀, Nepal. C. S. (S.) guptai Mutin, 1998, paratype, ♀, India. D. S. (S.) kumaoniensis Mutin, 1998, Ƌ, Myanmar. E. S. (S.) quadriseta Huo & Ren, 2006, ♀, China. F. S. (S.) uncinata Hippa, van Steenis & Mutin, 2015, paratype, Ƌ, Myanmar. Scale bars = 1.0 mm.

Fig. 3. Head, lateral view (C, E), and dorsal view (A–B, D, F). A. Sphegina (Sphegina) abbreviata sp. nov., paratype, ♀, Nepal. B. S. (S.) angustata sp. nov., paratype, ♀, Nepal. C. S. (S.) angustata sp. nov., paratype, Ƌ, Nepal. D. S. (S.) guptai, 1998, holotype, Ƌ, India. E–F. S. (S.) quadriseta Huo & Ren, 2006, ♀, China. Abbreviations: a = width of head; b = width of vertex; c = width of ocellar triangle; d = length of frons; e = length of ocellar triangle. Scale bars = 0.5 mm.

Fig. 4. Sphegina (Sphegina) angustata sp. nov., holotype, Ƌ. A. Posterior part of 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. 19. Metaleg, anterior view. A. Sphegina (Sphegina) abbreviata sp. nov., paratype, ♀, Nepal. B. S. (S.) angustata sp. nov., paratype, ♀, Nepal. C. S. (S.) uncinata Hippa, van Steenis & Mutin, 2015, Ƌ, Myanmar. D. Sphegina (Asiosphegina) brevipilis sp. nov., paratype, Ƌ, China, abbreviations: a = length of basitarsus of metatarsus; b = width of basitarsus of metatarsus. E. S. (A.) collicola sp. nov., holotype, Ƌ, Malaysia. F. S. (A.) crinita sp. nov., paratype, ♀, Java, abbreviations: a = length of metafemur; b = width of metafemur. Scale bars = 0.5 mm.