Allometopon selenis, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 56-57

Allometopon selenis spec. nov.

Figs 239–244

Description. General: ( Figs 239, 240 ) Body length approximately 3.6mm. Arista short plumose. M1+2 ratio 4.7. First flagellomere slightly enlarged, higher than long.

Chaetotaxy: Three fronto-orbital setae, anterior seta ¾ length. Ocellar seta thin, approximately 1.5 times length of tubercle. Postvertical seta very thin, as long as tubercle. Frons with minute setulae. Interfrontal seta miute. 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. Acrostichal seta small. Two lateral scutellar setae, anterior seta smaller.

Colour—male: Setae yellow. Frons yellow with ocellar tubercle dark brown; back of head yellow dorsally with one pair of stripes radiating from foramen that broadly join basally; remainder of head light yellow to white, possibly brownish around base of vertical setae; parafacial, gena and postgena silvery tomentose. Lateral and anterior stripe on scutum brown with lateral margin of postpronotum light yellow; posterolateral corner and posterior margin of scutum mottled brown; one pair of thin brown complete stripes along dorsocentral rows that are united by brown spot on posterior 1/3. Scutellum yellow with small anteromedial spot and lateral and posterior margins broadly brown. Katatergite yllow; anatergite and mediotergite brown with venter yellow. Pleuron and legs light yellow. Halter yellow. Wing clear. Abdominal tergites and sternite 8 brown; basal 2/3 of epandrium brown.

Male terminalia: ( Figs 241–244 ) Sternite 6 weak, confluent with hypandrium. Sternite 7 weakly sclerotized. Cerci small. Surstylus approximately 2/3 length of epandrium, bare on outer surface; shape irregular with apex subtriangular and posterior surface produced into long, flat, medially directed lobe; inner-apical setae stout, relatively short, with marginal setae rounded and tubercle-like; short, regular setae on inner surface of posterior lobe and transverse medial carina. Hypandrium dominated by sternite 6 anteriorly, mostly concentrated along arm posteriorly, with one medial seta and enlarged, pitted ventral lobe. Phallapodeme broad, plate-like, with shallow transverse carina apically along deep apical dome. Pregonite small, irregular, with several medial setae. Postgonite stout, narrow and long, with two apical setae and several inner setae at medial elbow. Basiphallus large, welldeveloped, ending in small convex epiphallus. Distiphallus very short, thin and narrow with minutely tuberculate medial bands. Paraphallus well-developed, tapered apically and with long dorsal spinules.

Colour—female: As described for male except as follows: body length approximately 4.1mm; M1+2 ratio 3.9; setae brown; colour darker, with only gena and venter of parafacial and face whitish; first flagellomere dirty yellowish-orange with dorsal half brown, becoming paler anteriorly; face and parafacial black, excluding white venter and orangish region between antennal bases; posterior margin of frons dark brown (including region around vertical setae), connected to one pair of brown sublateral stripes that narrow and become orange anteriorly; scutum dark brown excluding medial yellow stripe on anterior 2/3 except anterior margin, and with one pair of very small faded yellow spots on posteromedial margin; venter of postpronotum yellowish-white; mediotergite brown and anatergite only brown posterodorsally; abdominal tergites yellow laterally.

Female from Buri differs from female paratype as follows: acrostichal setae thinner and more inset; stripe on first flagellomere darker and more distinct; frons dark brown with small orange anteromedial emargination; paired stripes on back of head and dorsal margin brown; notum entirely dark brown excluding light yellow venter on postpronotum; mid and hind tibiae broadly light brown medially; fore tarsus brownish; abdominal tergites more broadly brown dorsally.

Female terminalia: Not dissected.

Etymology: The specific epithet is Greek for "crescent", referring to the yellow arch on the brown scutellum.

Distribution: Papua New Guinea.

Holotype: PAPUA NEW GUINEA. Morobe Province: Bubia, near Lae, 27.xii.1963, D.K. McAlpine (1♂, AMSA).

Paratype: PAPUA NEW GUINEA. Same data as holotype (1♀, AMSA).

Additional material examined: PAPUA NEW GUINEA. Buri near Samambata, Popondetta subdist., 30.x.1963, D.K. McAlpine (1♀, AMSA).

Comments: A brown scutellum with a complete yellow arch is most diagnostic of this species. The scutum also has a yellow anteromedial stripe that in the male is flanked by one pair of additional yellow intra-alar stripes. Neither of these features are present in the non-type female (not included in the above key), which is tentatively included because of other unusual similarities with the paratype female, including characteristic black striping on the frons and face. The shape of the surstylus is also unique to this species, as is the shape of the postgonite and the basal widening and texturing of the hypandrial arm.

Figures

FIGURES 239 – 244. Allometopon selenis spec. nov., holotype; 239: photo, dorsal; 240: same, lateral; 241: external genitalia, left lateral; 242: inner surface surstylus; 243: external genitalia, posterior; 244: internal genitalia, left lateral.