Allometopon atribatum, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 16-17

Allometopon atribatum spec. nov.

Figs 19–23

Description. General: ( Figs 19, 20 ) Body length approximately 3.3mm. Arista plumose with hairs more densely arranged towards base (slightly less dense in female). First flagellomere subcircular. M1+2 ratio 3.4–3.6.

Chaetotaxy: Posterior fronto-orbital absent; anterior fronto-orbital approximately 1/3 length of second frontoorbital. Ocellar seta approximately as long as second fronto-orbital. Postvertical seta absent. Interfrontal seta absent. Frons bare, glossy. First flagellomere with long marginal hairs. Anterior dorsocentral slightly shorter than posterior dorsocentral; widely spaced with anterior seta closer to transverse suture than posterior seta. Scutum glossy between dorsocentral setae with few sparse setulae. Acrostichal seta absent. Two lateral scutellar setae with anterior seta small.

Colour—male: Setae yellow to slightly brownish. Antennae yellowish-white with wide infuscation around arista base. Frons dark brown; head yellow to whitish below antenna; parafacial and gena light silvery tomentose; back of head dark brown above foramen. Notum dark brown with venter of postpronotum light yellow and posterolateral corner of notopleuron yellowish. Pleuron and legs yellowish-white. Halter yellowish-white. Wing lightly infuscated, becoming clear posteriorly. Abdominal tergites, annulus, epandrium and base of surstylus dark brown.

Colour—female: As described for male except as follows: setae brown; palpus dark brown with apex yellow; parafacial, gena and postgena dark brown; meron and anepisternum dark brown; legs past midpoint of femora yellow with tibiae dark brown excluding base and apex, and fore tarsus brown with base of basal segment fading to yellow; tergites 1–6 dark brown, cercus yellow; remainder concealed within abdomen, not visible.

Male terminalia: ( Figs 21–23 ) Annnulus well-developed with posterior margin of sternite 8 weakly sclerotized. Epandrium slightly higher and wider than long, dorsum slightly pointed. Cerci separate but converging apically; reduced to sclerotized distal margin of broad membranous perianal region. Surstylus strongly arched, nearly C-shaped, projecting posteriorly; outer surface bare anteriorly; inner surface with apical margin and distal half of posterior margin with relatively long tubercle-like setae. Hypandrial arm directed posteriorly, ventral region with two small setae before membranous region extending to basiphallus. Phallapodeme rod-like with long ventral shield. Pregonite clear, globular with two small adjoining setae. Postgonite small, clear and slightly longer than wide; two apical setae and one inner-medial seta. Basiphallus very small with basal section weakly sclerotized. Epiphallus consisting of two small, stout, dark and thinly connected sclerites. Distiphallus approximately 2/3 length of phallapodeme, abruptly elbowed at 2/5 length, and narrow with apex very shallowly bifid and midpoint of distal section with shallow lateral process. Paraphallus nearly as long as distiphallus; apex flat, pointed and leaflike with margins serrated; with flat subbasal process.

Female terminalia: Not dissected.

Etymology: The specific epithet describes the characteristic arista (L. batus, for a “prickly bush”), and its relatively dark colour (L. ater, for “black”).

Distribution: Malaysia (Pahang).

Holotype: MALAYSIA. Pahang: Cameron Highlands, W. Malaysia, 8.iv.1985, D.K. McAlpine (1♂, AMSA),

Paratype: MALAYSIA. Same as holotype except 4.iv.1985 (1♀, AMSA).

Comments: Allometopon atribatum ( Malaysia) , A. bharetum ( India) ( Figs 24, 25 ), and A. antennalis ( Indonesia, Malaysia, Philippines) ( Figs 6–10 ) are unusual among Allometopon species in a number of respects discussed above, but they most notably have a long anterior dorsocentral seta that is widely separated from the posterior dorsocentral, the hairs on the arista are usually densely arranged basally, there are only two fronto-orbitals and the scutum is glossy and bare posteromedially. Allometopon atribatum is distinct from these in having a long ocellar seta, two lateral scutellar setae, and a darkly pigmented frons, scutum and scutellum. The female is even darker with a dark parafacial, gena and postgena, an almost entirely brown palpus and brown tibiae. The surstylus is chevron-shaped and the internal genitalia are unique—the distiphallus is long, narrow and sharply angled medially, the paraphallus is long and stalked with a broad, serrated, blade-like apex, and the epiphallus consists of two globular sclerites.

Figures

FIGURES 19 – 23. Allometopon atribatum spec. nov., holotype; 19: photo, dorsal; 20: photo, lateral; 21: external genitalia, left lateral; 22: same, posterior; 23: internal genitalia, left lateral.

FIGURES 24 – 28. Allometopon bharetum spec. nov., holotype; 24: photo, dorsal; 25: photo, lateral; 26: external genitalia, left lateral; 27: same, posterior; 28: internal genitalia, left lateral.

FIGURES 6 – 13. Allometopon antennalis Sasakawa; 6: darker Philippine male, dorsal; 7: paler Philippine male, dorsal; 8: same, lateral; 9: holotype, dorsal; 10: same, lateral; 11: non-type external genitalia, posterior; 12: same, right lateral; 13: internal male genitalia, left lateral.