Nothybus acrobates Frey

Lonsdale, O. & Marshall, S. A., 2016, Revision of the family Nothybidae (Diptera: Schizophora), Zootaxa 4098 (1), pp. 1-42 : 14-16

Nothybus acrobates Frey

Figures 31, 32

Nothybus acrobates Frey 1958: 38 . Steyskal 1977: 30 [Oriental catalogue].

Description. Head: Light yellowish-orange in base colour. First flagellomere dark brown except for pale basal margin. Face white tomentose on ventral half with medial dark brown glabrous spot. Frons with dark velvety patches well developed, posteromedial patch pentagonal and not reaching base of setae; ocellar tubercle black. Labellum with blackish lateromedial spot.

Thorax: Yellowish-orange in base colour. Postpronotum mostly light yellow; brown to dark brown dorsally (band tapering anteriorly) and along anteroventral margin; dorsal half iridescent. Scutum with brownish, ill-defined medial stripe between two rows of setulae; posterolaterally with thin, short, floating, ill-defined reddish-brown stripe on dorsocentral row that is broken at suture and thicker presuturally; region above wing base reddish-brown; reddish-brown presuturally lateral to dorsocentral row, being darker around and anterior to light yellow notopleural tubercle. Scutellum brownish with apical margin yellow and posterolateral margin narrowly orange-yellow; subscutellum brownish dorsally. Burmese specimens with medial scutal stripe slightly more distinct, lateral stripe sometimes indistinct presuturally and anterior margin of scutellum yellowish. Katatergite and anatergite brownish. Pleuron mostly light yellow; oblique orange-brown stripe extending from anterodorsal corner of anepisternum to posterodorsal margin of katepisternum (colour only conspicuous on katepisterum and posteroventral margin of anepisternum), continuous with dark ventral stripe on postpronotum anteriorly; whitish-yellow stripe from posterodorsal corner of anepisternum to meron; posterodorsal corner of anepisternum brown; supporting sclerites below wing base mottled with light brown. Four very regular, widely spaced rows of presutural acrostichal setulae in medial patch; lateral patch of 2 additional rows of setulae not clearly differentiated from medial rows.

Wing: Wing length 8.9mm. As described for N. biguttatus (two clear, iridescent subapical wing spots) with apical cloud on CuA1 nearly indistinct. Calypter margin dark brown. Halter yellowish. Base of R4+5 with several very small, thin hair-like setulae ventrally.

Legs: Light yellow with apices of femora brown, tibiae dark brown with base paler; tarsi dark brown with slightly more than distal half of fore basitarsomere white excluding narrowly dark brown apex.

Abdomen: Mostly yellow, but becoming increasingly mottled with orange from tergite 3 to tergite 1. Tergite 1 with broad, ill-defined, dark brown medial stripe and with posterior margin broadly dark brown; tergites 2–6 with broad, dark brown, velvety posteromedial spot with anterior margin faded and slightly produced medially; lateral margin of tergites 1–4 narrowly dark brown; tergite 5 dark brown posterolaterally.

Male terminalia: Unknown.

Distribution. Burma, Laos.

Holotype: LAOS. “Muong Om”, [19.9˚ N 102.1 ˚E], 19.i.1919, R. Vitalis de Salvaza (1♀, UZMH). Additional Material examined. BURMA. Mt. Victoria, Chinhills, 1400m, iv.1938, G. Heinrich (1♀, BMNH), Bumgahtaung, 10.iii.1934, R. Malaise (1♀, BMNH).

Comments. Nothybus acrobates and N. biguttatus are here grouped in the N. biguttatus species group on the basis of similar colouration. In both species the wing is very darkly pigmented distal to dm-cu from cells r1 to r4+5, excluding two clear iridescent spots. Congeners otherwise either lack the clear, iridescent subapical wing spots ( N. longicollis ) or have three clear spots.

Figures

FIGURES 31, 32. Nothybus acrobates Frey, holotype female; 31: ventral; 32: right lateral. FIGURES 33 – 35: N. biguttatus Wulp, female, photos; 33: dorsal; 34: head, anterior; 35: left lateral.