Figs 2 B, 3 D
Material studied. Holotype male. RUSSIA, Krasnoyarsk region, Dikson Island, Konus Islet, Korotkevich, 31.VII.1948 (in ZIN). Paratypes. RUSSIA, same data as holotype, 3 males (1 in SDEI, 2 in ZIN). Other material. RUSSIA, Arkhangelsk oblast, Novaya Zemlya, Tuylenya Zaliv, 10.VII.1901, Timofeev, 1 male (in ZIN); Kemerovsk oblast, river Mrassu on upper river Tom, 15.VII.1908, Hvorov, 1 male (in ZIN).
Description. Male. Head. Face brown, maxillary palpus pale yellowish. Eye bridge and face not well visible in the specimens studied. Clypeus with 2–3 setae. Maxillary palpus with 3 segments, 1 st segment longer than 3 rd segment, 2 nd segment shortest; 1 st segment with 5–6 setae, with dorsal patch of sensilla; surface of antennal flagellomeres smooth, body of 4 th antennal flagellomere 2.25–2.35x as long as wide, the neck shorter than broad, the longest setae shorter than the width of flagellomere. Thorax. Dark brown, setae pale. Anterior pronotum with 7–12 setae. Proepisternum with 8–17 setae. Scutellum with 4 longer and some short and fine setae. Wing. In poor condition in the specimens studied. Fumose. Length 2.2–2.3 mm. Anal lobe weak. Veins distinct. c/w 0.55. Halter yellow. Legs. Yellow, coxal setae pale. Fore tibial organ forming a patch in depression. Fore tibial spur longer than the tibial width.
Abdomen. Pale brown, setae pale and fine. Hypopygium (Fig. 2 B). Brown, as abdomen. Intergonocoxal area moderately long, with 2 long separate setose lobes. Gonocoxa moderately broad, slightly longer than gonostylus, medial margin basally strongly curved, with sparse setosity. Gonostylus (Fig. 3 D) long, apically truncate, strongly impressed; with normal setosity, a short apical tooth, and 7 rather short and slender megasetae; with 1 well-differentiated whiplash seta on ventromedial margin of the apical fourth of gonostylus. Tegmen subtriangular, laterally slightly curved, apically roundish, laterally and apically sclerotized; aedeagal teeth not detectable in the specimens studied. Aedeagal apodeme long.
BIN. Unknown.
Discussion. The above description is based only on the type material. In its rather tumid gonostylus, Trichocoelina dicksoni sp. n. resembles most T. absidata sp. n. For distinguishing characters, see under the latter.
Etymology. The species is named after the Swedish merchant and philanthropist Oskar Dickson (1823–1897), after whom the type locality of the species, Dikson Island, was named.