Allometopon juxtum, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 36-37

Allometopon juxtum spec. nov.

Figs 131–136

Description. General: ( Figs 131, 132 ) Body length approximately 2.7mm. Arista short plumose. M1+2 ratio 5.0. First flagellomere subovate, higher than long, more produced dorsally. Female unknown.

Chaetotaxy: Three fronto-orbital setae, anterior seta 2/3 length. Ocellar seta approximately 1.5 times length of ocellar tubercle. Postvertical seta absent. Interfrontal seta minute. Margin of first flagellomere past base with hairs longer than width of arista base. Anterior dorsocentral half length of posterior dorsocentral; closely set posteriorly. Acrostichal seta not much longer than surrounding setulae. One small lateral scutellar seta.

Colour: Setae yellow, darker on dorsum of abdomen. Head mostly light yellow, whitish below frons and foramen and dorsomedially on back of head; antennae yellowish-white with dorsal 1/3 of first flagellomere brown towards base; basal 2/3 of arista white; parafacial, gena and postgena silvery tomentose; ocellar tubercle dark brown. Thorax light yellow, darker dorsally; with one pair of short, floating brown postsutural stripes that touch dorsocentral rows and are approximated on posterior half; scutellum narrowly brown dorsally. Legs yellowishwhite. Halter yellow. Wing lightly clouded anterodistally. Abdomen yellow with dark brown dorsomedial stripe on tergites 2–6.

Male terminalia: ( Figs 133–136 ) Annulus relatively narrow with sternites 6 and 7 weakly sclerotized. Cercus narrow, finger-like, with four long setae (one lateral, three apical). Surstylus approximately ¾ height of epandrium, width nearly twice height, outer surface setose medially; anteriorly with shallow lobe and posteriorly with longer lobe that has flat, irregularly produced plate covering brush of long, stout setae; inner surface with dorsomedial arch of thickened setae (tubercle-like anteriorly) and ventromedial arch of minute, stout pointed setae in dense patch. Hypandrium band-like with single inner seta and anterior margin produced as short, thin sheet. Phallapodeme broad and plate-like on distal half; dome-like apically with head extended as transverse carina. Pregonite membranous, either not evident or with several small setae. Postgonite with medial spines on inner surface and apex with posterior point and small rounded lobe with single inner seta. Basiphallus well-developed, fused to broadly lobate epiphallus. Distiphallus approximately 2/3 length of phallapodeme, narrow and minutely textured. Paraphallus large, broad, membranous and apically tapered with dorsomedial band of spinules.

Etymology: The specific epithet is from the Latin for “close”, “next to”, referring to the closely spaced scutal stripes.

Distribution: Papua New Guinea.

Holotype: PAPUA NEW GUINEA. East Sepik Province: Bainyik, 12.xii.1963, D.K. McAlpine (1♂, AMSA).

Paratype: PAPUA NEW GUINEA. same collection as holotype, 13.xii.1963 (1♂, AMSA), 21.xii.1963 (1♂, CNC).

Comments: Short floating scutal stripes that are inset basally are characteristic of this species, as is the brown dorsal spot on the scutellum, the limited dorsobasal pigment on the first flagellomere and the otherwise pale colouration. The surstylus is also diagnostic in being much larger than the epandrium and very broad with a tuft of posteroapical spines, and a strong whorl of spine-like and tubercle-like setae in the inner face. The cercus is also unusually long and narrow, the postgonite is unique in morphology and the paraphallus is very broad.

Figures

FIGURES 131 – 136. Allometopon juxtum spec. nov., holotype; 131: photo, dorsal; 132: same, lateral; 133: external genitalia, left lateral; 134: inner surface right surstylus; 135: external genitalia, posterior; 136: internal genitalia, left lateral.