Allometopon platystylum, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 52-53

publication ID	https://doi.org/ 10.11646/zootaxa.4106.1.1
publication LSID	lsid:zoobank.org:pub:A5ADF236-5219-4014-9DC4-C43F981DD1A4
DOI	https://doi.org/10.5281/zenodo.3504437
persistent identifier	https://treatment.plazi.org/id/6866497B-F124-3440-FF39-A0E3F13CFDFE
treatment provided by	Plazi
scientific name	Allometopon platystylum
status	sp. nov.

Treatment

Allometopon platystylum View in CoL spec. nov.

Figs 219–223 View FIGURES 219 – 223

Description. General: ( Figs 219, 220 View FIGURES 219 – 223 ) Body length approximately 2.7mm. Arista short plumose. M1+2 ratio 4.4. First flagellomere ovate, higher than long. Female unknown.

Chaetotaxy: Three fronto-orbital setae, anterior seta ¾ length. Ocellar seta approximately three times length of tubercle. Postvertical seta very thin, about as long as tubercle. Interfrontal seta minute. Frons minutely setulose. First flagellomere along distal margin with hairs longer than width of base of arista. Anterior dorsocentral half length of posterior seta; closely set posteriorly. Acrostichal seta absent; very few setulae posteromedially. One short lateral scutellar seta.

Colour: Setae yellow, brown on abdomen. Antenna including base of arista white; frons brown with large light yellow anteromedial spot; head below antenna and foramen yellowish-white, mostly brown behind head above foramen; parafacial, gena and postgena silvery tomentose. Notum dark brown with elongate light yellow spot on supra-alar row behind suture, and venter of postpronotum and notopleuron around base of anterior seta light yellow. Pleuron and legs light yellow to whitish. Halter white. Wing lightly clouded, becoming clear posteriorly. Abdomen yellow with tergites dark brown excluding lateral margin; sternite 8 dark brown, and epandrium dark brown excluding distal margin.

Male terminalia: ( Figs 221–223 View FIGURES 219 – 223 ) Epandrium broad and deep. Cerci small, converging, reduced to short-setose sclerotized bands along apex of perianal membrane. Surstylus very broad, nearly as large as epandrium in profile, base narrower, and posterior margin produced as flat, shallow, rounded lobe with small point. Sternite 6 confluent with transverse medial bridge of hypandrium, forming parallel arm reaching epandrium; hypandrium reduced to weak arm, single medial seta and membranous transverse section underlying sternite 6, partially fused to phallapodeme. Phallapodeme large, plate-like and well-developed with very large, deep apical dome with shallow carina. Pregonite flat, irregular, setose and produced dorsally to fuse to hypandrium. Postgonite well-developed, long and narrow with bifid, setose apex. Basiphallus fused to apical fin-like epiphallus and lateral wing-like processes developed from sclerotization of underlying membrane. Distiphallus short and smooth with narrow apex. Paraphallus small, narrow and smooth with bifid apex.

Etymology: The specific epithet uses the Greek for “broad”, “wide”, “flat” (platys), referring to the characteristic surstylus.

Distribution: Papua New Guinea.

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

Comments: Allometopon platystylum is almost entirely brown dorsally with a white antenna, yellow anteromedial region of the frons, and one pair of elongate yellow spots on the supra-alar row behind the suture. Similar pale scutal stripes are seen in A. lunatum ( Fig. 137 View FIGURES 137 – 142 ), A. marginale ( Fig. 184 View FIGURES 184 – 187 ) and A. phenomena ( Fig. 213 View FIGURES 212 – 218 ), but in these taxa the stripes are slightly longer and curve inwards to follow the transverse suture. The surstylus is immediately diagnostic, being broad, flat, slightly incurved posteriorly, and nearly as large as the epandrium in profile. The internal terminalia are unusual, characterized by a parallel set of sclerotized “arms” derived from sternite 6 that follow the outer surface of the hypandrial arms, the pregonite is flat and twisted, the postgonite is bifid apically (also seen in A. horridum ; Fig. 118 View FIGURES 113 – 119 ) and the paraphallus is smooth and similarly split apically.