Allometopon fumihalteratum, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 24-25

Allometopon fumihalteratum spec. nov.

Figs 57–63

Description. General: Body length approximately 2.3mm (♂), 2.9–3.1mm (♀). Arista short plumose. M1+2 ratio 4.4–5.0. First flagellomere slightly enlarged, higher than long, pronounced on anterodorsal margin in male. Clypeus broader, thicker in female.

Chaetotaxy: Three fronto-orbital setae, anterior seta 4/5 length. Ocellar seta approximately twice length of tubercle. Postvertical seta approximately as long as tubercle. Interfrontal seta small. Frons with minute setulae. First flagellomere along distal and anterodorsal margins with hairs longer than width of arista base. Anterior dorsocentral less than half length of posterior dorsocentral; closely set posteriorly; region between dorsocentrals almost entirely bare. Acrostichal seta absent. One small lateral scutellar seta.

Colour—male: ( Figs 57, 58 ) Setae yellow, brownish on notum and brown on abdominal tergites. Frons dark brown with deep yellow anteromedial spot; back of head above foramen brown with yellowish dorsomedial spot; basal 1/3 of arista white; remainder of head light yellowish-white; parafacial, gena and postgena silvery tomentose. Notum brown. Pleuron and legs yellowish-white. Halter knob brown. Wing lightly clouded, becoming clear posteriorly. Abdominal tergites, sternite 8 and epandrium excluding distal margin brown.

Colour—female: ( Fig. 59 ) As described for male except as follows: setae brown, paler on whitish sclerites; antenna orange with dark brown stripe above and brownish mottling below; back of head brown with venter yellow; remainder of head below antenna dirty yellowish-orange, with face slightly blackish, clypeus brown, distal half of palpus lightly infuscated, inner margin of parafacial and venter of gena (except posterior region) with shining dark brown strip, dorsum of postgena brown, and parafacial, gena and remainder of postgena light yellow; legs light yellow with fore femur brownish subapically, mid and hind femora dark brown on distal half excluding apex, fore tibia dark brown with apex yellowish, mid tibia dark brown, hind tibia brown with apex yellow, and fore tarsus whitish; wing darker, with deeper pigment from costa to midpoint of cell R2+3; abdominal tergites dark brown to tergite 7, with remainder retracted and not visible excluding yellow cercus.

Male terminalia: ( Figs 60–63 ) Sternite 5 with short, reduced setae medially. Sternites 6 and 7 weakly sclerotized. Cerci separate, small, converging. Surstylus short, narrowed and rounded apically, angled anteriorly and with short posterobasal thumb-like process; mostly bare on outer surface, long-haired on posterior margin; inner surface with short, stout setae on apical and posterodistal margins of surstylus and basal process. Hypandrium with reduced to relatively short arm, and bare, band-like medial bridge; with long, weak membranous ventral sheet with single distal seta. Phallapodeme partially rod-like, subapically broad and shallowly dome-like. Pregonite long, narrow and weakly sclerotized with cluster of apical and subapical setae. Postgonite longer than wide, with three very dark, thickened apical setae. Basiphallus well-developed, mostly separate from epiphallus, which has fused to ventral membrane to form thickened plate that curves upwards laterally. Distiphallus short, thin, weakly textured. Paraphallus slightly shorter than distiphallus, weakly textured.

Female terminalia: Not dissected.

Etymology: The specific epithet refers to the dark halter of this species, using the Latin for “smoke-coloured” (fumidus).

Distribution: Papua New Guinea.

Holotype: PAPUA NEW GUINEA. East Sepik Province: Bainyik, 21.xii.1963, D.K. McAlpine (1♂, AMSA).

Paratypes: PAPUA NEW GUINEA. East Sepik Province: Imbia, near Maprik, 19.xii.1963, D.K. McAlpine (1♀, AMSA), Kuminibus, near Maprik, 17.xii.1963, D.K.McAlpine (1♀, AMSA).

Comments: Like several other Papua New Guinea Allometopon , A. fumihalteratum is a yellow species that has the dorsum almost entirely dark excluding the antenna and anteromedial region on the frons, which are white to yellow. Unlike these other species, the halter knob is greyish-brown, the surstylus is relatively short and apically narrowed with a short, round basal process, the phallapodeme has a shallow apical dome but the full length of the shaft is still well-developed, the distiphallus and paraphallus are both short and smooth, the epiphallus is produced as thick, upcurved sheets laterally, and the postgonite has three unusually thick apical setae.

Figures

FIGURES 57 – 63. Allometopon fumihalteratum spec. nov.; 57: holotype male, photo, dorsal; 58: same, left lateral; 59: female, photo, left lateral; 60: holotype sternite 5, ventral; 61: external genitalia, left lateral; 62: same, posterior; 63: internal genitalia, left lateral.