Diostracus (Sphyrotarsus) kustovi, Grichanov, 2013

Grichanov, Igor Ya., 2013, West Palaearctic species of the genus Diostracus Loew, 1861 (Diptera: Dolichopodidae), European Journal of Taxonomy 61, pp. 1-14 : 7-11

Diostracus (Sphyrotarsus) kustovi sp. nov.

( Figs 1 A–E, 2, 3A, B)

urn:lsid:zoobank.org:act:C06CA79F-16D5-45ED-8309-8BCD4613E37C

Diagnosis

Scutellum with 3 pairs of almost equally long bristles; antennal scape bare above; male and female postpedicel about as long as high, with dorsal stylus; male 2 nd and 3 rd abdominal sterna with strong black spines; male 4 th abdominal sternum with bundle of setae; male with modified legs and simple wings.

Etymology

This species is named after the Russian dipterologist Dr. Semyon Kustov (Krasnodar).

Type material

Holotype

RUSSIA: ♂, Karachai-Cherkessia , Arkhyz env., Sofiiskie waterfalls, 43°26’09” N, 41°16’03” E, 2400 m, 03 Aug. 2012, S. Kustov ( ZIN).

Paratype

RUSSIA: 1♀, same data as for holotype ( ZIN).

Description

Male

LENGTH (mm). Body 9.4, wing 7.8, antenna 1.5, hypopygium 2.25.

HEAD ( Figs 1A, B ). Bluish-greenish black, pollinose; clypeus shining green, weakly pollinose, 1/3 as wide as head; face about 1/5 as wide as head, almost as long as wide; ocellar bristles strong, vertical and postvertical bristles about 1/2 as long as ocellar bristle; postocular ciliation black, strong, nearly as long as postvertical on upper 1/2, finer and yellowish below; ventral 1/2 of postcranium clothed with many long yellow hairs, some of which as thick as vertical bristle; antenna with bare vase-like scape; pedicel with ring of short setae; postpedicel as long as high, rounded distally, with middorsal simple arista-like stylus; length (mm) of scape to pedicel to postpedicel to stylus (1 st and 2 nd segments), 0.16-0.11-0.2- 0.13-0.85; palpus ovate, 1.6 times as long as wide, 1/3 as long as eye height, slightly dilated at middle; palpus black in ground colour, glittering silvery by pollinosity, bearing short black setae on outer side and along margin; proboscis moderately large for the genus.

THORAX. Greenish black, with washed pollinosity; mesonotum with pair of blackish longitudinal stripes; acrostichals absent; 5–6 asymmetrical dorsocentrals; 1 humeral with 1-2 short setae in front, 1 posthumeral, 2 notopleurals, 1 sutural, 1 postsutural, 1 supra-alar, 1 postalar; scutellum with 3 pairs of strong scutellars, of which outer pair 2/3 length of median 4 bristles; proepisternum with about 10 yellow setae on its lower portion and with about 6 similar seta on its upper portion; scutellum about 3 times wider than long; postscutellum about 3 times as long as scutellum (similar to that in D. leucostomus ).

LEGS. Rather long, black with slight greenish or bluish tinge on coxae and femora; fore coxa concave on anterior surface towards tip, there clothed with short, fine hairs, also with row of short, black, blunt setae on anterodistal margin; fore femur moderately thick, strongly curved at basal 1/3, with very short, fine hairs; fore tibia slightly thickened, bearing 4 dorsal bristles, 2 posterodorsals at base, 1 long curled posterodorsal bristle at apex, 1/3 as long as tibia, and with double row of short, erect ventral setae; fore basitarsus ( Fig. 1C ) constricted and almost bare in 1 st quarter, thickened in 2 nd quarter, densely short setose; its thickening bearing 3 long, curled dorsal bristles, half as long as basitarsus, and row of 12 short blunt spinules; 2 nd to 4 th tarsomeres simple, bearing elongate setae dorsally; 4 th tarsomere with strong apicoventral seta; 5 th segment flattened dorsoventrally; pulvillus reduced, empodium spicular, claws strong, about half as long as 5 th segment; mid coxa covered with short fine white hairs anteriorly, bearing 3–4 strong apical dirty yellow bristles forming some kind of spine; mid femur ( Fig. 1D ) slightly curved, distinctly emarginated dorsally along basal half or more, with rather long yellow hairs and setae on anterior, dorsal and ventral surfaces of its basal 1/2, the vestiture slightly darker on dorsal surface; the longest setae twice as long as femur diameter; apical 1/2 of mid femur almost bare and bearing 2–3 anteroventral and 2–3 posteroventral short bristles; mid tibia straight, subapically thickened, short setose, with several anterodorsal and posterodorsal bristles and subapical ventral fringe of strong black bristles longer than tibia thickness; mid tarsus slender, simple and short setose, with reduced pulvillus and empodium; hind coxa bearing sparse short, yellow hairs outside; hind femur long and simple, only slightly curved, with about 6 fine anteroventral black setae in distal 1/2, not longer than femur diameter, with long, fine, subapical anterior bristle; hind tibia slender, bearing several longish bristles on anterodorsal and posterodorsal surfaces and shorter ones on anteroventral and posteroventral surfaces, with about 5 long blackish-brown apicoventral bristles, of which longest bristle reaching middle of basitarsus; hind basitarsus ( Fig. 1E ) slightly swollen at base, with 4 short dorsal setae, with about 10 long blackish and brownish fine bristles at base ventrally and anteriorly, longest seta more than half as long as basitarsus; next tarsomeres slender and simple; pulvillus and empodium reduced. Fore podomere length (from femur to tarsomere 5, mm): 1.77-1.96-1.37-0.40- 0.27-0.18-0.29 (0.45 with claws); mid leg: 2.86-2.95-1.65-0.54-0.33-0.23-0.33 (0.49 with claws); hind leg: 3.00-3.52-1.38-0.72-0.43-0.25-0.29 (0.40 with claws).

WING. S imple, almost hyaline, with simple veins; Sc developed; R 2+3 and R 4+5 weakly convex anteriorly; R 4+5 and M 1+2 almost straight and parallel behind level of dm-cu; M 1+2 weakly sinuate; ratio of part of costa between R 2+3 and R 4+5 to that between R 4+5 and M 1+2 = 73/57; ratio of cross-vein dm-cu to distal part of CuA 1 = 84/47; dm-cu perpendicular to both longitudinal veins; calypter blackish, with pale cilia; halter orange yellow.

ABDOMEN. Black, with washed pollinosity, with short black setae; 1 st tergum with long brownish setae and ciliated with long black bristles on posterior margin; 1 st sternum projected, with shallow transverse furrow anteriorly; 2 nd sternum ( Fig. 2 ) with medial bulb at anterior 1/3, bearing 2 adjacent black spines formed of long glued setae and directed anteriorly; 3 rd sternum ( Fig. 2 ) with twice as large bulb bearing 2 diverging black spines formed of long glued setae and directed anteriorly; 4 th sternum ( Fig. 3A ) with 2 median bunches of erect brownish setae on low convection, with posterior margin somewhat projecting and covered with short hairs; hypopygium ( Fig. 3B ) black, moderately large, with posterodorsal portion moderately produced and rounded; hypandrium subtriangular, narrow distally and bifurcated at apex; phallus simple; epandrial lobe short and narrow; surstylus brown, almost semicircular, with short hairs dorsally; cercus distinctly longer than epandrium, slightly swollen at base, band-like, simple, densely ciliated with long yellow setae.

Female

LENGTH (mm). Body 7.0, wing 8.0, antenna 1.4.

Similar to male except lacking male secondary sexual characters, otherwise as follows: 6 dorsocentrals of irregular length in left row and 8 dorsocentrals in right row; palpus not glittering silvery; legs and abdominal sterna simple; 6 th and 5 th terga and genital plates densely covered with fine long setae; no acanthophorites.

Remarks

Having bulbs on 2nd and 3rd sterna and bearing strong ventral spines or bunches on abdomen, the new species distinctly differs from other species of the subgenus Sphyrotarsus (see key below). D. (L.) spinulifer males also have a setose venter, but not bearing bulbs and thick spines. Some Chinese and Nepalese species of Diostracus were also described with male sterna ornamented with bunches of setae, spines or projections (e.g., Saigusa 1984; Yang et al. 2011), but strongly differing in many other characters.

Ecology

Both types of D. (S.) kustovi were collected together on stones at a stream (S. Kustov, pers. comm.) in high mountains at 2400 m above sea level.

Figures

Fig. 1. Diostracus (Sphyrotarsus) kustovi sp. nov. Male holotype. A. Head in anterior view. B. Head in lateral view. C. Fore tarsus. D. Mid leg. E. Hind tibia in apical view and basitarsus.

Fig. 2. Diostracus (Sphyrotarsus) kustovi sp. nov. Male holotype. Abdominal segments 2 and 3.

Fig. 3. Diostracus (Sphyrotarsus) kustovi sp. nov. Male holotype. A. Apex of abdomen and hypopygium. B. Hypopygium. Abbreviations: cer – cercus, ep – epandrium, hyp – hypandrium, ph – phallus, sur – surstylus.