Thinophilus longicercus, Grichanov, 2023

Grichanov, Igor Ya., 2023, A review of the Afrotropical Thinophilus Wahlberg, 1844 (Diptera: Dolichopodidae), with the descriptions of ten new species, European Journal of Taxonomy 878, pp. 1-52 : 29-31

Thinophilus longicercus sp. nov.

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Fig. 9

Diagnosis

Thinophilus longicercus sp. nov. keys to T. imperialis (see key above), both species having male cercus very long, thin distally, extending to the base of abdomen, and sternites 3 and 4 of abdomen with tuft of mainly black hairs. Fore tibia bears 3–4 dorsal bristles, not longer than tibia width in T. imperialis , but fore tibia with 3–4 dorsal bristles, 2 × as long as tibia width in T. longicercus ; surstylus shape is different in the two species.

Etymology

The specific epithet ‘ longicercus ’ (Latin) refers to the ‘long cercus ’ of the male hypopygium.

Material examined

Holotype MADAGASCAR • ♂ (partly covered with mould); “ Lagoon shore; Fenerive [= Fenoarivo Atsinanana; 17°22′ S, 49°25′ E]; Dec. 1955; B. Stuckenberg leg.; Hydrophorus bisetus Loew ; P. Vanschuytbroeck det. 1957; I.R.Sc.N.B. I.G. 20938”; RBINS.

Description

Male ( Fig. 9A )

MEASUREMENTS. Body length 6.3 mm; antenna length 1.1 mm; wing length 5.2 mm; wing width 1.6 mm.

HEAD. Postcranium bluish black, grey pollinose; frons bluish black, weakly pollinose; face and clypeus greenish black, brownish grey pollinose; face under antennae 1.8 × as wide as height of postpedicel; clypeus half as long as epistoma, 1.6 × as wide as long; palp yellow, bearing black bristly hairs; proboscis black; 2 diverging ocellars; 1 vertical, 1 postvertical, much stronger and longer than, and not in row with upper postoculars; upper postoculars uniseriate, black; lower postoculars multiseriate, white, long; antennal scape, pedicel and postpedicel black dorsally, orange ventrally; scape invisible; pedicel simple, convex on inner side; postpedicel rounded, with short pubescence, slightly higher than long (18/14); arista-like stylus dorsal, black, thick basally, thin distally, shortly pubescent.

THORAX. Metallic bluish black, grey dusted; mesonotum darker, with matt black postalar spot; no acrostichals; 6–7 dorsocentrals decreasing in length anteriorly; scutellum with 2 strong marginals and 2 minute laterals; few upper and lower, white propleural bristles of different length.

LEGS. Fore coxa brown-black; mid and hind coxae black, orange-yellow at apex, grey pollinose; legs mostly dirty yellow, darker at knees; tibiae and tarsomeres 1–3 brown or black at tips; tarsomeres 4–5 brown-black. Fore leg ( Fig. 9B ). Coxa with long black setae and apical bristles; femur thickened, with ventral and posteroventral rows of strong bristles, about half as long as femur height; tibia bearing 3–4 long erect dorsal bristles, ventral row of short thick spinules, posteroventral row of elongate setulae, 2 long apicoventral bristles, devoid of black setulae anteriorly; basitarsus with ventral row of short thick spinules and posteroventral row of elongate setulae; segment 5 weakly widened and flattened; length of femur, tibia and tarsal segments (in mm): 1.63/1.42/0.64/0.29/0.19/0.16/0.17.

MID LEG. Coxa with black setae and bristles; femur with 2 ventral rows of short setae, at most ⅓ as long as femur height; tibia bearing 3 anterodorsal; 2 posterodorsal, 3 anteroventral, 2 posteroventral, 4 apical bristles; segment 5 inconspicuously widened; length of femur, tibia and tarsal segments (in mm): 1.89/ 1.97/1.02/0.34/0.26/0.22/0.22.

HIND LEG. Coxa with 1 black exterior bristle; femur ( Fig. 9C ) ventrally with anteroventral row of bristles, about femur height; 3 anterodorsal bristles; tibia bearing 4 anterodorsal, 4 posterodorsal bristles, 2 anteroventral, 3 posteroventral, 4 apicals; segment 5 inconspicuously widened; length of femur, tibia and tarsal segments (in mm): 2.73/2.8/0.67/0.54/0.37/0.24/0.26.

WING ( Fig. 9D ). Fumose, without distinct dark spots; veins brown; distal part of M 1+2 convex; tip of R 4+5 parallel with M 1+2; ratio of part of costa between R 2+3 and R 4+5 to that between R 4+5 and M 1+2 (in mm), 0.5/0.28; crossvein dm-m straight; ratio of dm-m to distal part of M 4, 0.4/0.58; anal vein distinct; halter dirty yellow; lower calypter dirty yellow, with white and brown cilia.

ABDOMEN. Shining green-black dorsally, weakly dusted; shining blue-violet laterally; tergites 2–4 ventrally whitish pollinose; setae and hind-marginal bristles black, short; sternites 3 and 4 of male abdomen with tuft of mainly black long hairs. Hypopygium ( Fig. 9E–F ) black with black appendages; epandrial lobe reduced to small subtriangular projection, glabrous; hypandrium short, fused with epandrium, apically concave; phallosoma narrow, weakly projected; phallus long and simple, concealed; surstylus flat and broad, at middle slightly wider than at base (lateral view), with several short inner and ventral bristles at base, with few short outer bristles at apex; cerci dorsally separated, very long, extending to base of abdomen, broad on basal third, filiform distally, with marginal bristles ( Fig. 9E ; distal half of cercus broken).

Female

Unknown.

Notes

The holotype bears an identification label by P. Vanschuytbroeck, “ Hydrophorus bisetus Loew ”. The latter species was reported from Madagascar from 4 specimens ( Vanschuytbroeck 1957), but only one male was found in RBINS collection, belonging to the new species described here. Hydrophorus bisetus was excluded from the Afrotropical Region by Dyte & Smith (1980).

Figures

Fig. 9. Thinophilus longicercus sp. nov., holotype, ♂ (RBINS). A. Habitus. B. Fore leg, posterior view. C. Hind femur. D. Wing. E. Hypopygium after maceration with basal half of cercus, lateral view. F. Distal appendages of hypopygium after maceration, ventral view.