Tenuopus birketti Grichanov, 2019

Grichanov, I. Ya., 2019, New Afrotropical species of Tenuopus Curran, 1924 (Diptera: Dolichopodidae), Russian Entomological Journal 28 (4), pp. 460-463 : 462-463

Tenuopus birketti Grichanov , sp.n.

Figs 3–4 .

MATERIAL. Holotype ♂, Mozambique: [Maputo Province,] Ponta Milibangalala, 24–30.VI.2006, P. Birkett ( NMSA); paratypes: 2♂, 4♀, same label ( NMSA; holotype and 1♀ paratype are dried from ethanol and mounted on pin); 1♂, South Africa: KZN [Kwa-Zulu Natal], Kosi Bay (2632DD), 30.XI–12.XII [1982?] ( NMSA; in glycerol in 2 vials mounted on pin).

DESCRIPTION. Male (somewhat discolorated). Head. Frons shining violet-black, weakly pollinose; one pair of short postvertical setae, shorter than uppermost postocular seta; upper postocular setae black, increasing in length upward; lateral and lower postoculars white; ventral postcranium covered with irregular white hairs; face silvery-white, 7 times as high as wide in middle, nearly as wide as postpedicel; clypeus slightly bulging; antennae as long as height of head, yellow; pedicel projected distally on inner side, with a crown of short black setae, one of dorsal setae nearly as long as pedicel; postpedicel elongate-ovate, longer than high at base (23/14); arista-like stylus dorsal, with short hairs; length ratio of scape to pedicel to postpe-dicel to stylus (1 st and 2 nd segments), 10/11/23/5/80; palpus and proboscis short, yellow, covered with white hairs, proboscis also with a pair of black lateral setae.

Thorax. Pleura dirty yellow; mesonotum orange, with brown-black stripe along acrostichals, wider posteriorly and brown on scutellum dorsally; 6 dorsocentral setae with 1 st pair small and posterior pair shifted laterally; acrostichals practically absent, few setae on anterior slope and 2 setae in middle; scutellum with 2 strong bristles and 2 short lateral hairs; proepisternum with 2 yellow setae.

Legs. Yellow; last segments of tarsi brown; fore coxa with white hairs anteriorly and 3 black apical bristles; mid coxa with black hairs anteriorly and 5–7 black apical bristles of various length; hind coxa with one long black outer bristle above middle; fore leg devoid of bristles and remarkable hairs; claws simple; mid femur with anterior preapical seta, glabrous ventrally; mid tibia with 2 long and 1 short anterior, 3 short posterodorsal, 2–3 short ventral, 4–5 apical setae; hind femur ventrally with simple setulae, with 1 strong anterior preapical bristle; hind tibia with 2–3 anterior, 4 short posterodorsal, 3–4 apical setae. Femur, tibia and tarsomere (from first to fifth) length ratio (in mm): fore leg: 1.02/1.09/ 1.06/1.60/0.47/0.24/0.14, mid leg: 1.27/1.90/1.17/0.57/0.45/ 0.26/0.15, hind leg: 1.48/2.50/0.58/0.77/0.46/0.27/0.15.

Wing. Evenly coloured, almost hyaline, veins yellow; subcosta very thin; ratio of part of costa between R 2+3 and R 4+5 to that between R 4+5 and M 1, 6/1; M 1 with gentle arc to apex, reaching costa right before wing apex; M 2 present as fold on membrane; cross vein dm-m straight, oblique; ratio of crossvein dm-m to apical part of M 1+2 (fork-handle) to apical part of M 4, 0.24/0.85/0.84; anal vein foldlike, not reaching wing margin; anal angle obtuse; lower calypter yellow, with dark apex and pale setae; halter yellow, halter stem thin and long, with dorsal and ventral groups of short hairs distally.

Abdomen. Mostly yellow-orange, black setose; 1 st segment yellow; 2 nd –5 th yellow, brown dorsally at posterior suture; 8 th segment and epandrium entirely yellow; 8 th segment with yellow and brownish setae; cercus and surstylus yellow; surstylus brown distally; cercus covered with yellow hairs and setae; hypandrium small, simple; phallus thin and simple; 2 epandrial lobes distally on each side; thick epandrial lobe with 5–6 apical setae; thin epandrial lobe with 2 apical setae; 2 long epandrial setae at base of hypandrium; surstylus nearly as long as cercus, simple, with short subapical dorsal tooth, with 2 short apical setae; cercus half as long as epandrium, swollen basally, narrow distally, covered with long setae dorsally and distally.

Measurements (in mm, in ethanol). Body length 4.2–4.8, antenna length 1.0, wing length 3.6–4.7, wing width 1.0–1.2.

Female. Similar to male except lacking male secondary sexual characters. Frons shining blue; face nearly parallelsided, 4 times as high as wide in middle; postpedicel subtriangular, with rounded apex, as long as high at base (15/13); length ratio of scape to pedicel to postpedicel to stylus (1 st and 2 nd segments), 15/11/15/6/102; mesonotum with shining green stripe along acrostichals; tibia and tarsomere (from first to fifth) length ratio (in mm): fore leg: 1.02/1.09/1.06/1.60/ 0.47/0.24/0.14, mid leg: 1.27/1.90/1.17/0.57/0.45/0.26/0.15, hind leg: 1.48/2.50/0.58/0.77/0.46/0.27/0.15; 7 th segment of abdomen brown; oviscapt small; terga 9+10 divided medially into 2 hemitergites, each bearing 5 long simple setae; anal plate weakly sclerotized, semicircular, adjacent to lateral processes covered with long hairs.

Measurements (in mm, in ethanol). Body length 4.5–5.2; wing length 3.9–4.2.

ETYMOLOGY. The species is named after the South African entomologist, P. Birkett ( NMSA), the collector of the type specimens .

DIAGNOSIS. T. birketti sp.n. is the smallest fly in the genus and belongs to a group of species with uniseriate acrostichals or without acrostichals, being the closest to T. soderlundi Grichanov, 2018 , differing from the latter in antennal postpedicel about 2 times as long as high and different morphology of epandrial lobes and surstylus. T. soderlundi has antennal postpedicel about as long as high. Both species differ from T. cognatus Parent, 1934 in abdomen with 2 nd –5 th segments almost entirely yellow and deeply furcated surstylus with narrow arms (see key below). T. birketti sp.n. female differs from T. cognatus and T. erroneus Parent, 1934 in abdomen with 3 rd –5 th segments almost entirely yellow (see key below).

Males

8. Abdomen with 2 nd –5 th segments mostly yellow orange, each with broad black posterior triangular spot; M 4 3 times longer than dm-m; antennal postpedicel as long as high; surstylus deeply furcated with narrow arms; body length 6 mm ..................................... T. cognatus Parent

— Abdomen with 2 nd –5 th segments almost entirely yellow; M 4 usually 4 times longer than dm-m; surstylus not furcated ...................................................................... 8a

8a. Antennal postpedicel as long as high; body length 5–5.2 mm .......................................... T. soderlundi Grichanov

— Antennal postpedicel about 2 times as long as high; body length 4.2–4.8 mm ................................ T. birketti sp.n. Females

22. Hind tarsus entirely black; R 4+5 and M 1 reaching costa at wing apex ......................................... T. cognatus Parent

— Hind tarsus yellow at base; M 1 reaching costa before wing apex .......................................................................... 22a

22a. Abdomen with 3 rd –5 th segments each with large blueblack posterior spots ........................ T. erroneus Parent

— Abdomen with 3 rd –5 th segments each with narrow brown posterior bands ...................................... T. birketti sp.n.

REMARKS. T. birketti sp.n. male from Kwa-Zulu Natal is remarkable in its smallest size, with wing length 3.6 mm, differing also from the Mozambiquean material in the reduction of some bristles on legs. Hypopygia of the two forms are identical; therefore, I consider their difference as an intraspecific variation. The collection sites for the two populations are located at a distance about 30–40 km from each other.

Figures

Figs 1–4. Tenuopus spp., males: 1–2 — T. comorensis Grichanov, sp.n.; 3–4 — T. birketti Grichanov, sp.n.; 1, 3 — head; 2, 4 — hypopygium, lateral view. Рис. 1–4. Tenuopus spp., самцы: 1–2 — T. comorensis Grichanov, sp.n.; 3–4 — T. birketti Grichanov, sp.n.; 1, 3 — голова; 2, 4 — гипопигий, сбоку.