Colobostema lastovkai, 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 : 220-223

Colobostema lastovkai sp. n.

( Figs 7 A-G)

Colobostema lastovkai Haenni, 1998 : Fauna Helv. 1, Diptera Checklist: 142, nomen nudum.

Type locality. SWITZERLAND, canton Graubünden, Swiss National Park , La Schera.

Material examined. Holotype ♂, labelled: «SU1SSE-GR-PNS, Alp La Schera , 2100m, Nardetum, 14.V1I.1980, J.-P. Haenni leg.», «S3283», «HOLOTYPE Colobostema lastovkai n. sp. ♂ Haenni, 1990» : the holotype is dry-preserved, micropinned in collection of MHNN, with tip of abdomen cleared and preserved in glycerine in a microvial fixed at the same pin as specimen. The holotype is in excellent condition. Paratypes (1 ♂, 1 ♀): 1 ♀, same date as holotype, but «S3638», preserved in alcohol, in coll. MHNN ; 1 ♂, same data as holotype, but «émergence, 25.VI-4.VII. 1979, M. Dethier leg.», «S3815», slide mounted, in coll. MHNN .

Other material. SWITZERLAND. GR: PNS, II Fuom , 1790 m, 15.VI.1980, 1 ♂, J.-P. Haenni, MHNN ; same, 24-26.VII. 1980, 1 ♂; same, 18.VIII. 1980, 1 ♀; Nationalpark, 2000, 1 ♂, P. Duelli, CGB : Savognin , 1360 m, 17-20.VIII.1988, 1 ♂, G. Bächli, MHNN ; Dischmatal , 6 ♂♂, 16-30.VI.1992, P. Brodmann, CGB / MHNN ; NE: Brot-Dessous , 2-16.VI.1994, 1 ♂, S. Barbalat, MHNN ; TI:

Campra di Là (Olivone), 1425 m, 23.V-1.VI.1994, 2 ♂♂, L. Pollini, MHNN ; Angone / Anzonico, 1550 m, 21- 31.VIII.1981, 1 ♂, G. Bächli, MHNN ; Lucomagno , 8.VIII.1997, 1 ♂, G. Bächli, MHNN ; VD: La Dole , 1500 m, 26.VII.2004, 1 ♂, G. Bächli, CGB ; VS: Morgins , Portes du Soleil, 27.VII.2004, 1 ♂, G. Bächli, CGB .— AUSTRIA. No specimen examined, but a drawing of the terminalia of a male specimen from «Austr. Alps» clearly belonging to this species was submitted to the author by Petr Lastovka (Lastovka in litt.)

Diagnosis. C. lastovkai belongs to the nigripenne group of species, with posterior margin of tergite 7 in male bearing a large median projection, surrounded by smaller angular lateral lobes. In C. lastovkai the median projection is triangulartrapezoidal, appearing truncate apically ( Fig. 7 A), in contrast to C. griseinerve , C. infumatum , and C. nigripenne , where this projection is more rounded and the lateral lobes differently shaped (care should be exercised with this character, since distinction may be difficult to appreciate in some cases). Additional characters are found in the shape of the aedeagus, characteristically contorted in C. lastovkai ( Fig. 7 C), and the shape of the epandrium, with elongate transverse pointed lobes ( Fig. 7 D). The female has a notched posterior margin of tergite 7 ( Fig. 7 F) and short and plump valvifers on sternite 8 ( Fig. 7 G).

Description. Male. About 2 mm long, dull brownish black, except katepisternum and meron shining; base of first antennal flagellomere usually light coloured; a pair of light spots on posterior corners of notum; wings slightly iridescent, slightly tinged with grey-brownish, darker in cells c and sc; anterior veins brown, posterior light brown, contrasting with membrane; halter with brownish stem, hardly contrasting with darker knob. Legs entirely dark except base of tibiae slightly contrasting. Light brown pilosity comparatively dense and elongated.

Head. Antennae shorter than length of head and thorax, widening apically, flagellomeres close together, with first flagellomere longer than wide, other flagellomeres wider than long, last flagellomere about as long as preceding two. Eyes widely separated on frons above antennae, by width of anterior ocellus.

Thorax. Notum slightly wider than long. Wing ( Fig. 7 E), 2.0-2.6 mm long. Membrane covered with coarse microtrichosity; M, with a well-marked angle, stem of vein anteriorly directed, hardly visible; M|+2 only slightly shorter than medial fork.

Abdomen. Tergite 7 with a large posterior median projection, triangular or trapezoidal, surrounded by a pair of short angular lobes ( Fig. 7 A). Sternite 7 with a shallow V-shaped posterior emargination ( Fig. 7 B). Genital capsule ( Fig. 7 C) rather broad, angular with pointed gonocoxites appearing blunt according to the angle of view, parameres blunt apically, aedeagus contorted, epandrium with laterally directed, pointed paired projections ( Fig. 7 D).

Female. Description lacunary due to the bad state of preservation of the few females known with certainty. The attribution of one of these specimens (GR: La Schera) to C. lastovkai is, however, certain: it was made possible because of the presence of the very typical terminal portion of the penis of this species, found accidentally broken in the reproductory ducts of this female, made evident by the clearing of the specimen in potash; tergite 7 with posterior margin notched medially ( Fig. 7 F); sternite 8 bearing a pair of basally widened, short and plump valvifers ( Fig. 7 G).

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

Distribution. Known only from a dozen localities in the Alps and Jura mountains of Switzerland, but apparently also present in the Alps of Austria (see above).

Ecology. C. lastovkai is a montainous species caught at altitudes ranging from 890 to 2100 m in various biotopes, including alpine meadow, pine forest and peatbog. The flight period extends from second half of May until end of August.

Derivation of name. The new species is named in memory of the late Petr Lastovka, distinguished Czech dipterist, who first recognized this taxon as distinct.

Figures

Fig. 7. Colobostema lastovkai sp. n.: A. Tergite 7, ♂. - B. Sternite 7, ♂. - C. Genital capsule, ♂, ventral. - D. Epandrium, distal part, ♂, dorsal. - E. Wing venation, ♂. - F. Tergite 7, ♀, with outline of another specimen (below). - G, Terminalia, ♀, with sternite 8.