Nanexila atricauda, Winterton, Shaun L., 2007

Winterton, Shaun L., 2007, New species of Nanexila Winterton & Irwin and Taenogera Kröber from Australia (Diptera: Therevidae), Zootaxa 1413, pp. 55-64 : 56-57

Nanexila atricauda sp. nov.

Holotype female, AUSTRALIA: QUEENSLAND: BS1 Longlands Gap, 6.iii-4.iv.1995, 17.28S 149.29E, 1150 m, P. Zborowski, FI [flight interception] trap, JCU (East) ( ANIC 29 021588) (Type #: T.144009) ( QMBA). Condition: excellent.

Diagnosis. Body bright orange, abdominal segments 7–8 and terminalia black; wing hyaline, tinted with orange; occiput with reflective gold pubescence medially, silver pubescence laterally.

Description. Female: Body length: 12.5 mm.

Head. Round in profile; eyes widely separated at narrowest point by width of ocellar tubercle; frons densely covered with matte black pubescence dorsally, velvet silver pubescence (velutum) on lower frons and face; lateral portion of occiput and gena covered with velutum pubescence, medially with gold velutum; multiple, poorly defined rows of orange postocular setae; slender, pale setae on gena; palp small and slender, palp and labellum pale orange-yellow with slender, white setae; antenna brown pubescent, longer than head; flagellum elongate and tapered, longer than combined length of scape and pedicel, style terminal, two segmented; dark setae on scape, pedicel and base of flagellum, longer on ventral and dorsal surfaces.

Thorax. Bright orange, largely glabrous with orange macrosetae; scutum and scutellum with sparse yellow pubescence and faint dorsocentral stripe, admixed with sparsely distributed, short, dark setae; pleuron overlain with sparse, yellow pubescence, slightly denser white pubescence on anepimeron, katepimeron, and meron, orange setae on proepisternum and katatergite; legs orange, coxae with sparse, orange pubescence, admixed with few, short, orange setae on anterior surfaces, stronger macrosetae dark orange and few in number; tibia and tarsi slightly darkened distally; haltere orange, knob pale distally; wing very faint orange infuscate, venation orange; scutal chaetotaxy (pairs): np, 3; sa, 2; pa, 1; dc, 2; sc, 1.

Abdomen. Bright orange except for black segments 7–8 and terminalia; short dark setae on all segments with longer pale setae laterally, tergite 1 with elongate pale orange setae along posterior margin; all setae of regular length, not reduced in length or concentrated medially.

Female genitalia. Genitalia not dissected.

Etymology. The specific epithet is derived from the Latin: atro, black and cauda, tail; referring to the distinct black tip of the abdomen.

Comments. Nanexila atricauda sp. nov. is closely related to N. gracilis ( Mann) . Both species are relatively large and slender compared to other species of Nanexila , and both are distinctively coloured bright orange. The male is unknown for this northern species, but it is easily differentiated from other Nanexila species by the attractively patterned head and black tip to the abdomen.