Colobostema schertenleibi, 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 : 231-233

Colobostema schertenleibi sp. n.

( Figs 10A-E )

Colobostema scIiertenleibi Haenni, 1998 : Fauna Helv. I, Diptera Checklist: 142, nomen nudum.

Type locality. SWITZERLAND, Ct. Neuchâtel: Cornaux (Les Rièdes).

Material examined. Type material. Holotype ♂ labelled «SUISSE-NE: Cornaux, Les Rièdes , 2.VI.2002, 566.920/208.350, 470m, J.-P. Haenni leg., garide / chênaie buissonnante» / « S 7078 « / « Colobostema schertenleibi n.sp. Haenni 2010 HOLOTYPE ♂ » . Paratypes (4 ♂ ♂): 1 ♂, same data as holotype ; 2 ♂ ♂, same data as holotype but « 10.V.2002 » , 1 ♂, same data as holotype but « 19.V.2001 » . The drypinned holotype is in excellent condition, with cleared tip of abdomen and genitalia preserved in glycerine in a microvial on the same pin as holotype. The holotype and the dry-pinned paratypes are deposited in the collections of MHNN.

Other material. ANDORRA. Vail Sant Roc (Santa Coloma), 1050 m, VIII.1992, 2 ♂♂, 1 ♀ ; same, IX.1992, 1 ♂ ; same, dates ranging from l.VI to 30.IX.1993, 7 ♂♂, all J. Pujade, FBUBA / MHNN . - CROATIA. Rijeka , 26.1 V.1995, 1 ♂, 26.IV. 1995, 0. Häland, MHNN , — FRANCE. Alpes-Maritimes : Lantosque (col de Turini W), 880 m, 12.VI.1994, 1 ♂, J.-P. Haenni, MHNN ; Ariège : Le Mas d’Azil, 307 m, 24.VI. 1991,! ♂, J.-P. Haenni, MHNN ; Indre-et-Loire: La Roche-Clermault , 21.IV.1990, 1 ♂, C. Cocquempot, INRAM / MHNN ; Lot: Carennac , 180 m, 12.IV.2010,! ♂, J.-P. Haenni, MHNN ; Boissières , 279 m, 16.VI.2012, 1 ♂, J.-P. Haenni, MHNN ; Montcléra ( Rudoux ), 160 m, 17.X.2012, 1 ♂, J.-P. Haenni, MHNN ; Var: Les Maures, Collobrières (vallon des Vaudrèches ), 10.VI.1994, 1 ♂, J.-P. Haenni, MHNN . - SWITZERLAND. GR: Grono Dorf , 350 m, 31.VIII.2006, 1 ♂, B. Merz, MHNG ; LU: Menzberg , 100 m, 3-6.VIII.1983, 1 ♂, G. Bächli, MHNN ; TI: Piano d’Arbigo , 21.VII.1991, 1 ♂, F. Rampazzi, MSNL ; Cevio , 10-11.IX. 1991, 1 ♂, G. Bächli, GBC ; Locarno env., (Brissago, Ronco s/Ascona, Locarno, Orselina, Minusio, Gordola), dates ranging from 25.III to 30.IX.1997, 89 ♂♂, M. Moretti, MSNL / MHNN (detail of captures in Haenni & Moretti in prep.) ; VS: Branson, Les Follatères , 600-800 m, 9.VI.2004, 4 ♂ ♂, J.-P. Haenni, MHNN ; Lens , 2004, 1 ♂, P. Duelli, CGB .

Diagnosis. Males of C. schertenleibi are easily recognizable by the apically truncate gonocoxites ( Fig. 10 C) (in most European species, gonocoxites are triangular in general shape, more or less pointed at apex), together with the very short tergite 7, about three times wider than long ( Fig. 10 A), a feature unique among the Palaearctic species of Colobostema . Based on characters of genitalia and pregenital segment, C. schertenleibi presents some similarities with the Nearctic C. varicorne (Coquillett, 1902), from which it differs however by the apically truncate gonocoxites.

Description. Male. 1.8-2.0 mm long. A dark species, appearing entirely dull black, with blackish-brown tinged wings; katepistemum and meron shining black, coxae partly shining; usual light spots at posterior corners of notum poorly developed and darker than usual, only slightly contrasting with rest of thorax; anterior part of costal cell darker, a faintly discoloured spot on wing between anterior margin of wing and bend of M t; halter with stem brownish and knob black; legs brown black except trochanters and extreme base of posterior femora, brownish, basal third of all tibiae contrasting yellowish brown, tarsi lighter brown, becoming darker towards apex.

Head. Antenna as long as head and thorax together, widening towards apex, with flagellomeres flattened and widened, first flagellomere much longer than wide, yellowish at base, following flagellomeres wider than long, last flagellomere about as long as preceding two together; eyes separated on Irons above antennae by about half width of anterior ocellus.

Thorax. Notum stout, quadrate, hardly wider than long; wing ( Fig. 10 E) 2.3-2.8 mm long, Mj with a marked bend and a short spurious stem directed anteriorad; M]+? hardly longer than medial fork.

Abdomen. Segment 7 with a complete sclerotized basal ring; tergite 7 ( Fig. 10 A) shortened, much wider than long, posterior margin slightly produced medially; stemite 7 (Fig. lOB) broad, encompassing tergite, emarginate posteriorly. Genital capsule rounded with apically truncate gonocoxites ( Fig. 10 C), parameres broadened, acute apically, aedeagus long, sinuate, epandrium prolonged posteriorly into a biiobed, somewhat flattened and arched projection, with lobes not diverging much, apically truncate ( Fig. 10 D).

Female unknown. Numerous females with peculiar habitus (flagellum of antenna with four basal segments contrasting yellow) have been trapped in Southern Switzerland (canton Ticino) by Marco Moretti in the localities where males of C. schertenleibi sp. n. were also numerous. However, genital examination of these females proved the presence of two different taxa, thence it is not possible to unambiguously associate any of them to the males described here of this new species.

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

Distribution. C. schertenleibi is South European in distribution, known from Andorra, France, and Croatia, and extending north to Switzerland. No capture prior to 1983 is known and the species has apparently become more common in recent years. Considering this fact and its isolated taxonomic place within West-Palaearctic species, C. schertenleibi might be an invasive species accidentally introduced into Europe in recent decades. Its origin, however, is presently unknown.

Ecology. C. schertenleibi has been frequently captured in thermophilous or submediterranean biotopes in Switzerland in recent years. In Ticino (Southern Switzerland), it was the most common Colobostema species in burned chestnut-forests studied by Moretti (Moretti & Haenni in prep.). Its flight-period extends from end of March to end of September.

Derivation of name. The new species is named in memory of my dear friend the late André Schertenleib, enthusiastic Swiss naturalist and entomologist, who took part in the collecting trip in the Southern Alps of France during which the first specimens of this new species were discovered.

Figures

Fig, 10. Colobostema scherienleibi sp. n.: A. Tergite 7, ♂. - B. Stemite 7, ♂. - C. Genital capsule, ♂, ventral. - D. Epandrium, distal part, ♂, dorsal, - E, Wing venation, ♂.