Allometopon acum, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 13-14

Allometopon acum spec. nov.

Figs 1–5

Description. General: ( Figs 1, 2 ) Body length 4.6mm. Arista pubescent. M1+2 ratio 2.8. First flagellomere reniform. Clypeus relatively broad, slightly thickened.

Chaetotaxy: Four fronto-orbital setae (decreasing in length anteriorly). Ocellar seta small, approximately 1.5 times length of ocellar tubercle. Postvertical seta thin, as long as ocellar tubercle. Interfrontal seta as long as ocellar seta. First flagellomere with anteroventral hairs longer than width of base of arista. Three dorsocentral setae positioned posteriorly on scutum, mid seta 2/3 length of posterior seta, anterior seta half length of mid seta. Acrostichal seta as long as mid dorsocentral. Lateral scutellar setae (2 pairs) long, subequal and with almost transverse arrangement.

Colour: Setae yellow. Body predominantly yellow; distal 1/3 of palpus dark brown; face, gena, parafacial and face whitish; gena and postgena silvery tomentose; scutum with thin brownish medial stripe reaching presutural region and with one pair of small floating presutural spots and postsutural stripes along intra-alar row; halter white. Wing clear. Abdominal colour unknown.

Male terminalia: ( Figs 3–5 ) Annulus well-developed with spiracle embedded. Epandrium broadly rounded with anterodistal margin continuing as narrow spine. Surstylus shorter than epandrium, narrow, pointed and strongly bent inwards. Cercus small and bilobed. Ventral lobe of hypandrium narrow, slightly produced and with two long distal setae; hypandrial arm long, directed posteriorly. Phallapodeme rod-like, well-developed with shield held close to venter of shaft along length. Epiphallus small, well-developed, projecting. Pregonite confluent with hypandrium, densely setose, curved anteriorly. Postgonite very long. Basiphallus relatively long and narrow. Distiphallus approximately 2/5 length of phallapodeme, with weak basal shield (similar to Sobarocephala , missing in related taxa). Paraphallus well-developed.

Female terminalia: Unknown.

Etymology: The specific epithet is derived from the Latin for "needle", referring to the unusual thin process on the epandrium.

Distribution: Sri Lanka.

Holotype: SRI LANKA. Gal. Dist. Kanneliya, 200ft., black light, 15–17.x.1976, Hevel, Dietz, Karunaratne & Balasooriya (1♂, USNM).

Comments: Allometopon acum belongs to the A. palpale species group, revealed by its is a large, robust body, apically dark palpus, strong acrostichal seta, two pairs of strong lateral scutellar setae arranged in a row across the scutellum and small, narrow subtriangular surstylus. Within the group, this species can be diagnosed by four fronto-orbitals, a black first flagellomere and a yellow thorax with faint brownish vittae on the scutum, including a pointed posteromedial stripe and one pair of floating lateromedial stripes broken at the suture. The epandrium has a narrow anteroventral process that is about as long as the surstylus, and only otherwise seen in its putative sister species A. hybos (southeast Asia). The species is known from a single Sri Lankan male, relatively disjunct from this otherwise southeast Asian clade.

Figures

FIGURES 1 – 5. Allometopon acum spec. nov.; 1: photo, dorsal; 2: photo, lateral; 3: external male genitalia, left lateral; 4: same, posterior; 5: internal male genitalia, left lateral.