Allometopon cavernosium, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 19-20

Allometopon cavernosium spec. nov.

Figs 29–34

Description. General: ( Figs 29, 30 ) Body length approximately 2.7mm. Arista short plumose to pubescent. M1+2 ratio 3.7–4.2. First flagellomere ovate, higher than long, more pronounced dorsally. Female unknown.

Chaetotaxy: Three fronto-orbital setae, anterior seta 2/3 length. Ocellar seta 1.5–2.0 times length of tubercle. Postvertical seta minute, shorter than tubercle. Interfrontal seta minute. Frons minutely setulose. First flagellomere along distal and anterodorsal margins with hairs longer than width of arista base. Anterior dorsocentral half length of posterior dorsocentral; closely set posteriorly on scutum. Acrostichal seta present, not much larger than surrounding setulae. One short lateral scutellar seta.

Colour: Head partially yellow; antenna yellowish-white below frons and foramen; ocellar tubercle dark brown; parafacial, gena and postgena silvery tomentose. Scutum yellow with pointed medial stripe that extends into presutural region or is reduced to posteromedial mottling. Scutellum yellow with dorsum light brown to brown. Metanotum yellow with dorsum of mediotergite and posterodorsal corner of anatergite brownish. Pleuron and legs yellowish-white. Halter yellow. Wing lightly clouded, becoming clear posteriorly. Abdominal tergites with broad dorsal stripe from posterior region of tergite 1 to sternite 8; epandrium brown basally.

Male terminalia: ( Figs 31–34 ) Sternites 6 and 7 weakly sclerotized. Cercus broad, setose. Surstylus approximately 4/5 height of epandrium, subrectangular in profile and with broad, bare posterior face; with large, thick, incurved posteromedial process; with stout setae on process, and inner-distal margin with several rows of tubercle-like setae. Hypandrium with one seta on posteroventral lobe (possibly homologous with pregonite) emerging near base of well-developed arm; weak anteromedially, partially fused to irregular distal margin of phallapodeme. Phallapodeme broad and plate-like with large, smooth apical dome. Postgonite small, lobate with two apical setae. Basiphallus and epiphallus relatively long, flat. Distiphallus short, narrow, minutely tuberculate. Paraphallus as long as distiphallus; lobate and mostly membranous with narrow, weakly sclerotized band with small dorsal spinules.

Etymology: The specific epithet refers to the unusually large, broad, concave phallapodeme of the species and the group to which it belongs, although it is particularly exaggerated here.

Distribution: Papua New Guinea.

Holotype: PAPUA NEW GUINEA. Oro Province: Kovelo, near Kokoda, 6.i.1964, D.K. McAlpine (1♂, AMSA).

Paratype: PAPUA NEW GUINEA. East Sepik Province: Kuminibus, near Maprik, 17.xii.1963, D.K. McAlpine (1♂, CNC), Oro Province: Popondetta subdist., Buri, near Sasembata, 31.x.1963, D.K. McAlpine (1♂, AMSA).

Comments: Allometopon cavernosium is a relatively pale Papua New Guinea species characterized by a short to long medial stripe, a yellow scutellum that is brown on the dorsal surface, no brown markings on the first flagellomere or the back of the head, and a yellow epandrium with a brown dorsobasal spot. The male terminalia are particularly diagnostic, with the surstylus subrectangular with a large posteromedial process, and the phallapodeme especially large and cavernous with no vestige of the apical section of the rod remaining.

Figures

FIGURES 29 – 34. Allometopon cavernosium spec. nov., holotype; 29: photo, dorsal; 30: photo, lateral; 31: external genitalia, left lateral; 32: same, posterior; 33: internal genitalia ventral; 34: same, left lateral.