(Figs 5 A-E)
Scatopse tristis Zett. var. griseinervis Duda, 1928: Scatopsidae, Fliegen pal. Reg. 2(1)5:39.
Type locality. ITALY, prov. Novara: Macugnaga, Mte Rosa.
Material examined. Holotype ♂, labelled: «Mte Rosa 4.8.00» [in Oldenberg’s handwriting] / «Macugnaga Oldenberg» / «Coli. Oldenberg» / «Typus» / « tristis Z. var. griseinervis oder n. sp. ♂ d. Duda» [in Duda’s handwriting] / «coll. DEI. Eberswalde»; I have labelled it « Colobostema griseinerve comb.n. JP Haenni rev. 1990 Holotype ♂ »; type specimen pinned, in good state, preserved in the collections of the DEI, Eberswalde.
Other material. AUSTRIA. Kärnten: Heiligenbild, 4.VTI1.1927, 1 ♂, coll. Oldenberg, DEI. — FRANCE, Alpes-de-Haute-Provence: Thorame-Haute (Orgeas), 2000 m, 1 ♂, 21.V. 1999, L. Micas, INRAM (Haenni & Withers 2007). - MONTENEGRO: Durmitor, 1500 m, 30.VII-5.VIII.1988, 1 ♂, G. Bächli, CGB. - SWITZERLAND. LU: Menzberg, 1000 m, 3-6.VIII.1983, 2 ♂♂, G. Bächli, CGB; TT: Bolle di Magadino, 17-20.VT.1995, 1 ♂, B. Merz & G. Bächli, MHNN; Locarno env., (Ronco s/Ascona, Locarno, Gordola, Orselina, Minusio, Cugnasco), dates ranging from 25.111 to 12.VIII.1997, 32 ♂♂, M. Moretti, MSNL/MHNN (detail of captures in Haenni & Moretti in prep.).
Diagnosis. Males of C. griseinerve can be separated from those of other European species of the nigripenne -group (that have tergite 7 strongly produced posteriorly medially) by the shape of the epandrium, which has posterior projections slightly but clearly asymmetrical, horn-like, pointed and rather heavily sclerotized (Fig. 5 D), and by the elongate gonocoxites, appearing either pointed or rounded at apex, according to the angle of view (Fig. 5 C).
Description. 1.9 mm long; brown black in general colour (type somewhat faded), dull except lower pleurae shining as usual; antennae entirely dark; wings greyish brown with a lighter zone above angle of M, that extends up to apex of R4+5; veins dirty brownish grey; legs concolourous with body except basal third of tibiae and tarsi lighter.
Head. Eyes approximated on frons above antennae, separated by less than half width of anterior ocellus; antennae slightly widening towards apex, flagellomeres comparatively closer to each other than is usual for the genus; first flagellomere longer than wide, second as long as wide, following wider than long, last flagellomere almost twice preceding one.
Thorax. Notum hardly longer than wide; wing (Fig. 5 E) densely covered with microtrichia; anteriorly directed stem spurious vein on M, conspicuous, long; M|+2 clearly shorter than medial fork.
Abdomen. Basal sclerotized ring of segment 7 incomplete; tergite 7 (Fig. 5 A) with narrow, apically pointed posterior projection and a pair of comparatively wide lateral expansions, inner fold well developed; sternite 7 (Fig. 5 B) with a shallow Vshaped posterior emargination; genital capsule (Fig. 5 C) with gonocoxites slightly asymmetrical, apically pointed or rounded, according to angle of view; parameres elongate; epandrium (Fig. 5 D) with heavily sclerotized, pointed, asymmetrical posterior projections, aedeagus of medium length, sinuous.
Female unknown.
Taxonomic remarks. Duda (1928) erected this «variety» for some supposedly aberrant specimens of C. tristis Zett., characterized by more or less grey wings and veins. As can be seen from his identification label of the type, he hesitated on what status to give to this form that he considered as «eine Uebergangsform von nigripennis zu tristis » (Duda 1928). This taxon has never been referred to since its description. It corresponds, however, to a very distinctive species belonging to the Mgripenne -group of species. The wing coloration features used by Duda (1928) are evidently insufficient to allow identification, as is demonstrated by the fact that the only other specimen of C. griseinerve (from Heiligenblut, Austria) seen by Duda had been labelled by him as tristis Zett. Duda attributed also to the variety griseinerve three specimens from Finland and Lappland based on rather trivial wing and legs coloration characters (which are variable and clearly of no taxonomic value in this genus); two of these specimens have been recognized since then as the types of a distinct species (C. dudai Krivosheina, see above under this species) and the latter specimen as belonging to C. infumatum (Hal.) by Krivosheina (2000).
Distribution. C. griseinerve has been recorded from France (Haenni & Withers 2007) and Switzerland (Haenni 1998). It is apparently restricted to the mountainous ranges of Central and South-Eastern Europe, with about 15 localities from the Alps of Austria, France, Italy, and Switzerland, and from the Durmitor range in Montenegro.
Ecology. Most occurences are from mountainous level, but there are also low altitude catches, especially from Switzerland south of the Alps (Ticino). Dates of capture when known range from March to beginning of August.