Allometopon antennalis Sasakawa, 2009

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 14-15

Allometopon antennalis Sasakawa, 2009

Figs 6–13

Allometopon antennalis Sasakawa 2009: 41 .

Description. General: ( Figs 6–10 ) Body length 2.8–3.2mm. Arista sparsely short plumose with hairs slightly denser to base. M1+2 ratio 4.3–4.6. First flagellomere small, circular.

Chaetotaxy: Two long fronto-orbital setae (not three, as stated in original description). Ocellar seta thin, shorter than tubercle. Postvertical minute. Interfrontal seta minute. First flagellomere with marginal hairs longer than width of base of arista. Three dorsocentral setae; anterior dorsocentral half length of second dorsocentral; second dorsocentral 3/5 length of posterior dorsocentral, and closer to transverse suture than posterior dorsocentral. Acrostichal seta absent. Postsutural scutum between dorsocentrals glossy, bare. One small lateral scutellar seta.

Colour—male: Setae yellow. Head mostly yellow; first flagellomere with dark brown dorsal stripe sometimes reduced on inner surface; ocellar tubercle brown; gena, face and parafacial dirty white; gena and postgena silvery tomentose; venter of back of head whitish. Thorax mostly yellow; scutellum brown dorsally, except along apical and lateral margins; scutal stripe tapering to suture (including in holotype; Figs 9, 10 ) or continuing to anterior margin as thinner line sometimes widened at apex, and sometimes with one pair of short basolateral stripes (faded in holotype) that sometimes partially fuse to central stripe ( Fig. 6 ); metanotum sometimes light brown with katatergite and mediotergite darker. Wing clear to faintly infuscated. Halter white. Legs yellow. Abdomen brown with epandrium darker, and with tergite 1 (sometimes brownish), surstylus and cercus yellow.

Variation—male, Malaysia: Body length 3.4mm; stripe on first flagellomere absent on inner surface; medial scutal stripe slightly exceeding suture, narrower and ill-defined laterally; lateral scutal stripes vestigial; scutellum narrowly brown dorsomedially and laterally; metanotum yellow with katatergite brownish anteriorly.

Colour—female: As described for male except as follows: first flagellomere with narrow infuscated line on dorsomedial margin beginning at arista base; edge of vertex with narrow brown line wider than ocellar tubercle; scutal stripe well-defined, not extending to yellow anterior margin, and posterolateral stripes present, separate; notopleuron brown and supra-alar region possibly brownish; brown spot on dorsum of scutellum wider, more sharply delimited; katepisternum whitish-yellow with brown spot on anterior face; wing lightly infuscated; abdomen yellow with wide brown dorsal stripe from tergite 1 to 5; surstylus slightly more opaque distally; abdominal stripe narrowing anterior to tergite 5, tergite 6 light brown.

Male terminalia: ( Figs 11–13 ) Annulus well-developed with seventh spiracle free from sclerite. Epandrium broadly rounded with anterodistal corners slightly projecting. Cercus projecting, weakly sclerotized on outer surface. Surstylus nearly as long as epandrium, subtriangular with posterior margin broadly rounded; outer face bare excluding posterobasal margin; with broad, clear and slightly sunken distomedial region that makes surstylus appear bifid. Ventral lobe of hypandrium small with two small medial setae. Phallapodeme rod-like, welldeveloped, with ventral shield projecting distally. Basiphallus and epiphallus well-developed. Pregonite rounded, setose. Postgonite somewhat elongate, apically setose. Distiphallus slightly longer than basiphallus, narrow. Paraphallus hooked and strongly spinulose.

Female terminalia: Not dissected.

Distribution: Indonesia (Sulawesi), Malaysia (Perak), Philippines.

Holotype: PHILIPPINES. Luzon: Nueva Vizcaya, Dalton Pass, 915 m, 9–10.iv.1968, D.E. Hardy [Type No. BPBM 17191] (1♂, BPBM).

Additional material examined: INDONESIA. Sulawesi Utara, Dumoga-Bone N.P., low forest ca. 200m, ‘Rothamsted 2’, 1985, Malaise trap, R. Ent. Soc. Lond., Project Wallace, B.M. 1985-10 (2♀, BMNH). MALAYSIA. Perak: Belum-Temenggor: Pulau Banding (15km env), 5°33′5′′N 101°20′33′′E, 300–400m, 27.iii–14.iv.2015, E. Jendek & O. Sausa, CNC 440241 (1♂, CNC). PHILIPPINES. Mt. Apo, Mindanao, Philippine Islds, C.F. Clagg, Sibulan Riv., 2000ft., 8.x (1♂, MCZ), Galog Riv., 6000ft., 8.ix (1♂, CNC), Mainit Riv., 6500ft., 24.ix (2♂, MCZ), 7.x (1♂, MCZ).

Comments: Allometopon antennalis can be confused for other vittate species with a bicoloured scutellum, but it has a scutum that is more extensively yellow, the scutellum is mostly yellow with brown dorsobasal spot, the hairs on the arista are shorter, the clypeus is brown and the surstylus is strikingly different.

Figures

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.