Dilophus sardous, Haenni, 2009

Haenni, Jean-Paul, 2009, The Bibionidae (Diptera) of Sardinia, with description of two new species *, Zootaxa 2318, pp. 427-439 : 435-437

8. Dilophus sardous sp. nov.

( Figs 10–16)

Type locality. Italy, Sardinia (Cagliari province [= Carbonia-Iglesias prov. since 2005]): Iglesias , Monti Marganai , Tintillonis , 480 m, UTM 32 S 463010 4355249 .

Type material. Holotype ♂ labelled: “I – Sardegna (CA [= Carbonia-Iglesias prov.]) / Iglesias M.ti Marganai / località Tintillonis 480m / 11-12.VI.2004 (Malaise) / UTM 32 S 463010 4355249 / D. Birtele, P. Cerretti, G. Nardi, M. Tisato, D. Whitmore leg./ Progetto Sardegna – CNBF” [print], “ Centro Nazionale per lo Sudio / e Conservazione della /Biodiversità forestale – CNBF / Verona – Bosco della Fontana / Corpo Forestale dello Stato / Progetto Sardegna ” [print], “ Dilophus sardous sp. nov. ♂ / HOLOTYPE / J.- P. Haenni 2007” [partly handwritten, red label].

Paratypes: same data as holotype, 367 ♂♂, 89 ♀ ; Carbonia-Iglesias province , Iglesias , Marganai, near Case Marganai, 660 m, UTM 32S 0463341 4556196, hand net, leg. D. Birtele, P. Cerretti, G. Nardi, M. Tisato & D. Whitmore 5.VI.2004, 1 ♀ ; 6.VI.2004, 2 ♂♂ .

Remarks: Holotype in good condition, dry pinned, paratypes partly dry pinned, partly preserved in alcohol, in coll. CNBFVR except 20 males and 10 females in coll. MHNN, Neuchâtel.

Other material examined. C07: 20–24.V.2006, 2 ♂♂, 3 ♀. C23: 19–24.V.2006, 1 ♂. C70: 7.VI.2004, car net [= entomological hand net held outside the window of a moving car], 2 ♂♂; 8.VI.2004, car net, 3 ♂♂. C82: 7.VI.2004, hand net, 11 ♂♂, 3 ♀; 9–12.VI.2004, several hundreds of males and females of both sexes; 12.VI.2004, 29 ♂♂, 6 ♀. S3: 7.VI.2004, hand net, D. Birtele, P. Cerretti, G. Nardi, M. Tisato, D. Whitmore leg., 1 ♂. SAR1: 15–30.VI.2004, 20 ♂♂, 1 ♀; 20.V–16.VI.2005, Malaise trap and window flight trap, 13 ♂♂, 12 ♀; S2: 16–30.V.2006, 3 ♂♂, 2 ♀; 30.V–13.VI.2006, 1 ♂, 1 ♀ (all CNBFVR).

Diagnosis. Among the west Palaearctic species of the Dilophus febrilis -group (those species with only 2 sets of spines on anterior tibiae), D. sardous may be distinguished by the following combination of characters: in both sexes, the median row of spines of anterior tibiae consists of three spines only ( Figs 12–13), while most other species have four spines, the anterior one often more or less separated from the others; it is unique for males, the deep parallel-sided posterior incision of sternite 9 ( Fig. 16), combined with the shape of the gonostyle (which is only weakly angled; Fig. 15), and the milky white wing membrane with hardly contrasting, whitish pterostigma and translucent, not contrasting posterior veins ( Fig. 10); D. femoratus Meigen (generally distributed in Europe) males have milky white wings and a similar posterior incision on sternite 9, but strongly angled, axe-shaped gonostyles; D. maderae Wollaston (from Madera) has a similar posterior incision of sternite 9 and quite similar gonostyles, but light brownish wings with strongly contrasting brown pterostigma and brown veins (see Haenni & Báez 2001); in females the brownish tinged wing with contrasting hind veins and the entirely fuscous abdomen with last sternite contrasting yellow is present otherwise only in D. neglectus Haenni, 1982 (from mountain ranges in Central Europe), which has four spines in the middle row on fore tibiae (3 spines in D. sardous sp. nov.) and both species differ in many male characters (shape of sternite 9 and gonostyles, etc) (see Haenni 1982).

Description. Male. Body 4.1–5.2 mm long. Shiny black in general colour, with light golden pilosity ( Fig. 10). Head black, rostrum hardly extending beyond base of antennae, eyes short pubescent, antennae short, with 9-segmented flagellum. Thorax strongly shining, polished black on notum and on most of pleurae; posterior margin of pronotum bearing a row of 12 spines, anterior margin of mesonotum with a row of 16 (rarely 18) smaller spines. Wing ( Fig. 10) 3.3–3.9 mm long, hyaline, appearing slightly milky white according to the angle of view; pterostigma whitish, more or less suffused of brownish along veins, not contrasting with membrane; anterior veins brownish, posterior veins hyaline, not contrasting with membrane. Halteres brownish black with yellowish-brown stem. Legs black, except apex of anterior coxa and most of outer surface and a broad longitudinal band on inner surface of anterior femur, contrasting brown. Femora shiny black. Anterior tibia ( Fig. 12) bearing two rows of well developed spines, a transverse set of three spines in an oblique row and an apical set of nine spines. Hind tibia and first hind tarsomere not modified, both weakly widening towards apex, the latter elongate and reaching nearly 2/5 of length of tibia. Abdomen black, shining, but less so than thorax. Hypopygium with posterior margin of sternite 9 ( Fig. 16) bearing a deep posterior median, more or less parallel-sided emargination reaching a third of length of sternite, tergite 9 straight or slightly concave on posterior margin ( Fig. 15), gonostyles ( Fig. 15) nearly straight, apically blunt pointed.

Female. Body 4.2–5.8 mm long, variegated black and yellow in general colour, with sparse and rather short golden yellow pilosity. Head ( Fig. 13) shiny black, antennae short, flagellum 9-segmented, the flagellomeres closely set but easy to count; whitish yellow pilosity more developed posteriorly, part of head anterior to the eyes less than half the height of eyes. Thorax. Notum shiny black, with postpronotal lobes rufous yellow, scutellum laterally and posteriorly more obscurely tinged with rufous; pleurae variegated, black and obscurely rufous. Prothoracic comb of 12 black spines, notal comb irregular, consisting of 12–14 smaller spines. Wing ( Fig. 11) 3.5–4.8 mm long; membrane slightly but distinctly tinged with brownish, pterostigma well marked, brown, strongly contrasting, anterior veins light brown, posterior veins light brownish, contrasting with membrane. Halteres brown with yellowish stem. Legs. Coxae and femora rufous yellow, trochanters darker, tibiae and tarsi black. Anterior tibia ( Fig. 13) with two rows of strong spines, a submedian transverse set of three spines in an oblique row and an apical set of nine spines. Abdomen entirely dark brown, with light pilosity, except for contrasting yellow sternite 9. In quite numerous specimens the anterior sternites are somewhat lighter coloured than posterior ones, frequently with a median longitudinal lighter band.

Etymology. The name sardous is an adjective referring to the geographic origin of the new species.

Chorotype. A probable Sardinian endemic element according to present knowledge, but its presence might be expected in Corsica.

Ecology. The new taxon appears to be abundant and widespread in the Monti Marganai and Montimannu areas at altitudes ranging from 480 to 700 m. Like several Dilophus Meigen species , D. sardous sp. nov. presents mass occurrences since several hundreds of specimens were caught by a Malaise trap during a short period in mid June.

Notes. Morphological variation appears reduced, although 2 males (from Tintillonis) with 4 spines in the median row of anterior tibiae were found.