Colobostema dudai Krivosheina 2001

Colobostema dudai Krivosheina, 2001

(Figs 2 A-G)

Colobostema dudai Krivosheina, 2001: Int. J. Dipterol. Res. 12(2):75, Figs l~5, 9, 11-15.

Type locality. RUSSIA, Karelskaia A. R., Lakhdenpokh’ya [formerly Jaakkima, Finland], Krivosheina (2001) stated that the type locality is in Finland on the base of the label of the holotype, but according to P, Vilkammaa (in litt.) this locality situated on the northern shore of Lake Ladoga is now in Russian Carelia.

Materiell examined. Holotype ♂ labelled: «Jaakkima / Forsius / 743 [printed, the latter on blue paper] / Scatopse tnstis Zett. [handwritten in red] /1 ris lis Zett. var griseinervis det Duda [in Duda’s handwriting] / Mus. Zool. FFfors Spec. typ. No 4723 S. tristis v. griseinervis Duda [partly handwritten] / Mus. Zool. Helsinki N:o 15167 [yellow printed label, number handwritten] / Mus. Zool. Helsinki Loan Nr D 0 0 - 65 [printed yellow label] / Holotypus ♂ Colobostema dudai Kriv. [in Krivosheina’s handwriting, red label] / Mus. Zool. Helsinki Loan Nr D 0 2 - 122 [printed yellow label]». The holotype deposited in the collection of ZMUH, Helsinki, is double-mounted, with tip of abdomen cleared and mounted in a drop of conservative medium on a piece of acetate pinned on the same pin as specimen; it is in rather poor condition, strongly faded and lackings several parts (flagellum of antennae, anterior right leg, tarsi of mid left leg and posterior left leg missing). Paratype ♀ labelled «Jaakkima» / «Forsius» / «760» / « Colobostema triste Zett. N. Krivosheina det. 1999» [in Krivosheina’s handwriting] / / Mus. Zool. Helsinki Loan Nr D 0 0 - 67 [printed yellow label] / Paratype ♀ « Colobostema dudai Krivosheina ». [in Krivosheina’s handwriting, red label] / Mus. Zool. Helsinki Loan Nr D 0 2 - 123 [printed yellow label]. Paratype preserved and prepared in the same way as the holotype, ZMUH.

Diagnosis. The posteriorly 4-lobed tergite 7 of the male (Fig. 2 A) and the elongate and pointed, nearly transverse and subapically anteriorly toothed terminal lobes of the epandrium (Fig. 2 D) are unique to this species among the Palaearctic representatives of the genus.

Description. Male. About 1.8 mm; entirely brownish, clearly faded, dull (except lower pleura, shining as usual).

Head. Eyes widely separated by width of anterior ocellus; antennae broken on type.

Thorax quadrate, as wide as long, pubescence on notum sparse; wing (Fig. 2 E) 2.0 mm, uniformly brownish; M1+2 shorter than medial fork; M, smoothly angled at basal '/4, with a short anteriorly directed spur of vein visible.

Abdomen. Pregenital segment with a complete basal sclerotized ring; tergite 7 (Fig. 2 A) with two pairs of rounded posterior lobes, outer shorter than inner one, slightly asymmetrical, ending in a point much developed on right lobe, but hardly indicated on left lobe; sternite 7 (Fig. 2 B) encompassing tergite, with a pair of elongate outer lobes, deeply emarginate on posterior margin, medially with a shallow inner emargination; genital capsule (Fig. 2 C) with shortened triangular, apically pointed gonocoxites, bearing an inner basal process apically acute, parameres elongate, epandrium with nearly transverse, elongate and pointed, subapically anteriorly toothed apical lobes (Fig. 2 D), aedeagus filiform with a preapical elongate swelling.

Female. Description fragmentary due to the poor state of preservation of the only known female specimen; about 1.9 mm; as male in colour and morphology; antennae complete, with flagellar segments wider than long except first hardly longer than wide; wing 1.8 mm; tergite 7 notched medially on the posterior margin (Fig. 2 F); valvifers on sternite 8 broadened, rounded apically (Fig. 2 G)

Taxonomic remarks. The male holotype was labelled triste var. griseinerve by Duda, who considered it as belonging to the same variety as a male from Macugnaga (Italian Alps) («ein gleiches Tier fand ich in der S. aus Helsingfors: ‘Joakima, Forsius 43. Sccitopse tristis Zett. ’ und ein ♂: ' Lapponia Palmen 635 Sc. infumata ’») (Duda 1928). However, the genitalic structure of the Jaakima specimen clearly differ from that of the Macugnaga specimen (see C. griseinerve, further on), while the other specimen from Lapponia in the Helsinki Museum belongs to infumatum (Hal.), according to Krivosheina (2001).

Distribution. Until now known only from the type locality, in Northern Russia (Carelia).

Ecology. Nothing is known on the ecology, biology and phenology of this species.