Colobostema geigeri, Jean-Paul Haenni, 2013

Jean-Paul Haenni, 2013, A revision of the West Palaearctic species of Colobostema Enderlein, 1926 (Diptera, Scatopsidae). Part I. European subregion, Mitteilungen Der Schweizerischen Entomologischen Gesellschaft 86, pp. 199-242 : 211-213

publication ID	https://doi.org/ 10.5169/seals-403072
DOI	https://doi.org/10.5281/zenodo.6157673
persistent identifier	https://treatment.plazi.org/id/0A78FC5B-224A-580F-C750-0249FE64F8C3
treatment provided by	Plazi
scientific name	Colobostema geigeri
status	sp. nov.

Treatment

Colobostema geigeri View in CoL sp. n.

( Figs 4 View Fig. 4 A-F)

Colobostema geigeri Haenni, 1998 View in CoL : Fauna Helv. 1, Diptera Checklist: 141, nomen nudum; Haenni 1999: Checkliste Dipt. Deutsch!. Studia Dipt. Suppl. 2: 74, nomen nudum.

Type locality. SWITZERLAND, canton Ticino: Vezia San Martino .

Material examined. Holotype ♂ labelled «CH-TI Vezia S. Martino , 410 m, 3-9.IX.1979, C. Dufour & W. Geiger » / «S3978»/ « Colobostema geigeri n.sp. ♂ HOLOTYPE Haenni 1990» . Paratype ♂, same data as holotype but « 16-22.VII. 1979 » and «S3979» . Holotype and paratype preserved in alcohol, in coli. MHNN. '

Other material. GERMANY. Nordrhein-Westfalen: Köln (Grüner Kuhweg NSG), 31.V-6.VI.1989, 1 ♂, J. Wehlitz, MHNN . - SWITZERLAND. VD: Les Grangettes, Gros Brasset , 19.VI.1992, 1 ♂, M. Sartori, MZL ; Changins , 2001, 1 ♂, P. Duelli, MHNN .

Diagnosis. In males the posteriorly shallowly emarginate tergite 7 ( Fig. 4 View Fig. 4 A), together with the shape of the epandrium, whose distal lobes are apically rounded and fused for a long distance ( Fig. 4 View Fig. 4 D) are characteristic of this species. The shape of the gonocoxites, triangular and shortened ( Fig. 4 View Fig. 4 C), is also unique among the Palaearctic species of Colobostema .

Description. Male. 2.0-2.3 mm long (in alcohol); brownish black in general colour (although somewhat discoloured by alcohol), with pilosity lighter; a pair of light spots at the posterior comers of the notum posteriorly to the wing bases; wings light brownish, anterior veins brown, posterior veins brownish; halters brown with lighter stem; legs concolourous with body, except basal third or fourth of tibiae and tarsi lighter.

Head rounded in general shape, about as long as high; eyes separated by about the width of the anterior ocellus; antennae long, flagellum 8-segmented, slightly widening towards apex; first flagellomere quadrangular, lighter on basal third, flagellomeres 2 to 7 widening and shortening progressively, well separated, somewhat cup-shaped.

Thorax. Quadrate; wing ( Fig. 4 View Fig. 4 F), 2.1-2.3 mm long; M(with a well marked angle at about basal third, but no visible anteriorly directed stem of vein; stem of M vein about as long as fork MjM2.

Abdomen. Pregenital segment with a complete basal sclerotized ring; tergite 7 wider than long, not produced posteriorly, but broadly emarginate medially ( Fig. 4 View Fig. 4 A) on posterior margin, appearing more or less undulated according to the angle of view; stemite 7 slightly emarginate on posterior margin ( Fig. 4 View Fig. 4 B); genital capsule ( Fig. 4 View Fig. 4 C) with characteristic triangular gonocoxites, pointed parameres, epandrium elongate, with apical lobes rounded, fused for a long distance ( Figs 4 View Fig. 4 D-E), aedeagus elongate, shortly emarginate apically.

Female unknown.

Taxonomic remarks. The quotation of C. geigeri in Haenni (1998, 1999) must be considered as nomen nudum (see above Colobostema auberti sp. n., ‘Taxonomic remarks’).

Distribution. The species is presently known from only four localities, in Switzerland and Germany.

Ecology. As far as can be infered from these scattered occurences, C. geigeri sp. n. seems restricted to lower elevations. Its flight-period extends from end of June to beginning of September.

Derivation of name. The new species is named in honour of my friend Dr Willy Geiger, Swiss entomologist and nature conservationist, who first collected this new species.