Hercostomus vikhrevi, Grichanov, 2020

Grichanov, Igor Ya., 2020, New species of Hercostomus Loew, 1857 from Afrotropics (Diptera: Dolichopodidae) and key to Afrotropical fauna, European Journal of Taxonomy 722, pp. 16-36 : 28-31

Hercostomus vikhrevi sp. nov.

urn:lsid:zoobank.org:act:6B3B05EE-C3BA-4CAB-B348-18A8EE96AFEE

Fig. 5

Diagnosis

The new species is close to H. balensis Grichanov, 2004 , and H. kefaensis Grichanov, 2004 , both known from Ethiopia, differing distinctly in its larger size, in morphology of the male fore tarsus, antenna, wing and hypopygium. In H. balensis , male fore tarsomeres 4–5 dark, with fringe of white erect hairs, 1.5–2 × longer than diameter of tarsomeres; wing with less deep postero-proximal emargination; basoventral lobe of cercus distinctly shorter than mid-ventral lobe; the latter lobe bearing three strong simple setae, half as long as the lobe. In H. kefaensis , the male postpedicel is 2.5–3 × longer than high; fore tarsomere 4–5 dark, with short semi-accumbent dorsal hairs, tarsomere 4 with black hairs and tarsomere 5 with black and white hairs; wing with less deep postero-proximal emargination; mid-ventral lobe of cercus with three strong simple setae, slightly longer than the lobe.

Etymology

The species is named for the collector of the holotype, Dr. Nikita Vikhrev (ZMUM, Moscow).

Type material

Holotype

KENYA • ♂; Laikipia County, Thomson's Falls ; 0.05° S, 36.38° E; 2350 m a.s.l.; 21–23 Dec. 2013; N. Vikhrev leg.; terminalia dissected and stored in glycerin in a microvial pinned with the specimen; ZMUM.

Description

Male ( Fig. 5 )

MEASUREMENTS (in mm). Body length 4.9; antenna length 1.3; wing length 5.2; wing width 1.5 ( Fig. 5A ).

HEAD. Frons greenish black, whitish pollinose; face black, densely white pollinose. One long, strong vertical pair of ocellar setae, 1 short postvertical, pair of ocellar setae. Upper postocular setae black; lateral, lower ones white. Eye with short hairs; face glabrous. Face gradually narrowed towards palpi, 5.1 × as high as wide in middle, under antennae about 1.3 × as wide as width of postpedicel, at clypeus approximately half as wide as width of postpedicel; clypeus not reaching lower margin of eyes. Antenna ( Fig. 5B ) slightly longer than height of head, entirely black; pedicel short, wide, internally convex anteriad, with short distal setulae; postpedicel asymmetrical, elongate, narrowed, angular apicodorsally, 1.4 × longer than high, covered with short pubescence; arista mid-dorsal, black, with short hairs. Length ratio of scape to pedicel to postpedicel to stylus (1 st – 2 nd segments), 21/15/26/14/81. Palpus, proboscis moderately small, yellow, with short black setae; palpus with 1 black bristle.

THORAX. Greenish black, greyish pollinose. Six strong dorsocentral setae; 2 rows of acrostichals, nearly half as long as dorsocentrals; 2 strong notopleural, 1 strong humeral, 1 posthumeral setae. Propleura

with 1 strong black seta above fore coxa, 2 groups of short light hairs. Scutellum with 2 strong setae, 2 lateral hairs.

LEGS. Including coxae dirty yellow; mid coxa brownish laterally; hind femur brown at extreme apex; hind tibia yellow-brown; tarsi black from tip of basitarsus, fore tarsomere 5 yellow, hind basitarsus brownish black. Fore coxa with black hairs anteriorly and several setae in apical half; mid coxa with 1 strong lateral seta in addition to anterior hairs; hind coxa with 1 strong lateral seta. Femora without long hairs. Fore tibia with 2 short posterodorsal setae. Fore tarsomere 3 flattened, strongly widened, 2.3 × longer than wide, with dorsal comb of short black setulae; tarsomere 4 with strong basodorsal black spine formed of 3 mostly fused bristles, with brush of white erect hairs; tarsomere 5 clear white, with dorsal fringe of white erect hairs, not longer than diameter of tarsomere ( Fig. 5C ). Length of fore femur, tibia and tarsomeres 1–5 = 1.54 mm, 1.64 mm, 0.91 mm, 1.08 mm, 0.42 mm, 0.13 mm, 0.2 mm. Mid femur with 1 anterior and 1 posteroventral subapical seta. Mid tibia with 3 anterodorsal, 2 posterodorsal and 5 apical setae. Length of mid femur, tibia and tarsomeres 1–5 = 1.91 mm, 2.75 mm, 1.62 mm, 0.9 mm, 0.69 mm, 0.33 mm, 0.21 mm. Hind femur with one subapical anterior seta. Hind tibia with 3 anterodorsal, 3 posterodorsal, 4–5 fine ventral, 5 apical setae. Hind tarsomeres 1–2 with 1–2 short apical setae. Length of hind femur, tibia and tarsomeres 1–5 = 2.45 mm, 3.06 mm, 0.95 mm, 1.19 mm, 0.69 mm, 0.37 mm, 0.26 mm.

WINGS. Simple, greyish, veins brown. Costa simple. R 1 reaching to first third of wing length. R 2+3 and R 4+5 weakly divergent. Ratio of part of costa between R 2+3 and R 4+5 to between R 4+5 and M 1+2, 61/16. R 4+5 and M 1+2 slightly convergent in distal part; M 1+2 joining costa at wing apex. Crossvein dm-m straight, forming right angle with both M 1+2 and M 4 longitudinal veins. Ratio of dm-m to distal part of M 4, 46/75. Wing anal lobe with broad and deep postero-proximal emargination. Anal vein fold-like; anal lobe pronounced. Lower calypter yellow, with black setae. Halter yellow.

ABDOMEN. Mostly greenish black, weakly pollinose, with segments 2–3 broadly reddish yellow laterally, segments 4–5 with brown lateral spots, with black hairs and long marginal setae. Segment 7 slightly longer than epandrium (93/84). Segment 8 large, covering more than half lateral side of epandrium, with fine short dark cilia. Genitalia ( Fig. 5D ) with epandrium orange yellow, rounded-oval, twice longer than high. Foramen positioned before middle of left lateral side. Hypandrium mid-ventral, with short base, 4 long thin lobes of different lengths and widths. Phallus thin, projected. Distoventral epandrial lobe as short rounded prominence, fused to epandrium, with 2 short, 1 very long setae. Surstylus yellow, bilobate; ventral lobe broad, simple, ¾ length of dorsal lobe, with 1 subapical seta; dorsal lobe of surstylus widened in distal half, with short narrow process at apex, several subapical setulae, 1 strong mid-dorsal seta. Distal lobe of postgonite as long as ventral lobe of surstylus, narrow, broad, pointed at apex. Ventral lobe of postgonite ( Fig. 5E ) strongly sclerotized, simple, covered with microscopic denticles on proximal side. Cercus ( Fig. 5F ) broad, yellow, densely covered with short light hairs, longer at apex, long strong setae at apex of cercus; cercus with 2 ventral lobes; basolateral lobe of cercus nearly as long as cercus, with bunch of about 9 long, curved at apex apical setae; mid-ventral narrow lobe with 3 pedunculate setae, thick on basal half, filiform on distal half, 2 times longer than lobe; 1 short strong seta between ventral lobes.

Female

Unknown.

Distribution

Kenya.

New locality records

Figures

Fig. 5. Hercostomus vikhrevi sp. nov., ♂, holotype (ZMUM). A. Habitus. B. Antenna. C. Fore tarsus. D. Hypopygium, right lateral view. E. Distoventral appendages of epandrium. F. Cercus.