Allometopon plicatum, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 53-54

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.3499674
persistent identifier	https://treatment.plazi.org/id/6866497B-F123-3441-FF39-A150F098FDDB
treatment provided by	Plazi
scientific name	Allometopon plicatum
status	sp. nov.

Treatment

Allometopon plicatum View in CoL spec. nov.

Figs 224–228 View FIGURES 224 – 228

Description. General: ( Figs 224, 225 View FIGURES 224 – 228 ) Body length 2.7mm. Arista short plumose. M1+2 ratio 3.1. First flagellomere slightly enlarged, produced dorsally and more broadly lobate ventrally. Female unknown.

Chaetotaxy: Three fronto-orbital setae with anterior seta approximately 2/3 length. Ocellar seta thin, slightly longer than tubercle. Postvertical seta thin, approximately as long as tubercle. Interfrontal seta absent. First flagellomere along distal and distoventral margins with hairs longer than width of base of arista. Anterior dorsocentral half length of posterior dorsocentral; closely set posteriorly. Acrostichal seta not much longer than surrounding setulae. One lateral scutellar seta.

Colour: Setae yellow. Head mostly yellow, white below antenna; first flagellomere with light brown dorsobasal patch on outer surface; ocellar spot dark brown, posterolateral corner of frons brown to base of inner vertical; back of head with one pair of brown stripes radiating from foramen; parafacial, gena and postgena silvery tomentose. Scutum yellow in ground colour; anterior and lateral margins brown with yellow spot along venter of postpronotum and anterior notopleuron; one pair of nearly complete intra-alar stripes (enclosing base of dorsocentral setae) that narrow to a break behind suture. Scutellum yellow with lateral corner brown. Metanotum brown with anatergite yellow ventrally. Pleuron and legs yellowish-white. Wing clear. Halter white. Abdomen yellow, tergites brown with lateral margin narrowly yellow (wider on tergite 2); sternite 8 brown dorsomedially and epandrium brown.

Male terminalia: ( Figs 226–228 View FIGURES 224 – 228 ) Annulus with segmentation mostly indistinct. Epandrium wider than high. Cercus small with short marginal setae. Surstylus large, bullet-shaped, higher than epandrium, and nearly as long as epandrium at base; posterodorsal corner produced past distal margin of epandrium; mostly bare on outer face anteriorly; distal and anterodistal margins with tubercle-like setae on inner face. Hypandrium partially fused to ventral portions of annulus; arm sinuate, closely held to long, shallow ventral lobe with two distal setae. Phallapodeme rod-like, with narrow, stout shield emerging from before midpoint. Pregonite membranous, large, apparently almost semicircular with several medial setae. Postgonite lobate with two apical setae. Basiphallus welldeveloped, fused to narrow, projecting epiphallus. Distiphallus complex, folded with lateral sheets connected by broad medial membrane, ventral half with margins more thickly sclerotized and drawn together at midpoint to form an “X”. Paraphallus with stout sclerotized base and long, clear tapering apical section that is dorsally spinulose and with ventral supporting sclerotized band along much of length.

Etymology: The specific epithet is Latin for “fold”, referring to the unusual folded shape of the distiphallus.

Distribution: Philippines.

Holotype: PHILIPPINES. Negros Oriental: Cuernos de Negros, 7km W. Valencia, 700m, 7–15.i.1988, D.C. Darling & E. Mayordo (1♂, ROME).

Comments: Allometopon plicatum is closely related to A. conopeum ( Fig. 41 View FIGURES 40 – 46 ) ( Papua New Guinea) and A. megastylis ( Fig. 188 View FIGURES 188 – 193 ) ( Philippines), largely revealed through colour and male genitalic morphology, especially the complex distiphallus, which is relatively short with the base and sides produced as sclerotized sheets. Furthermore, the ventral portion of the hypandrium is relatively broad and the arm is curved dorsally, the ventral shield of the phallapodeme separates from the shaft medially, the epiphallus is short and straight with a clear apical portion, the cerci are relatively small and nearly united, and the surstylus is large and subtriangular, rounded apically, with apical and medial marginal tubercles on the inner surface, and the posterobasal corner is produced past the posterior margin of the epandrium. Externally, these species have a medially yellow scutellum (only yellow apically in A. conopeum ; Fig. 41 View FIGURES 40 – 46 ), an entirely yellow pleuron, and a similar notal pattern consisting of one pair of lateral stripes and one pair of postsutural stripes that are pointed in A. plicatum and A. megastylis , and mirrored by a similar pair of presutural stripes in A. plicatum .

A similarly broad hypandrium and large, subtriangular surstylus are also seen in Allometopon punctulatum ( Fig. 234 View FIGURES 234 – 238 ) (Malaysia—Sarawak) and A. solare ( Fig. 253 View FIGURES 253 – 257 ) ( Thailand), which are likely related, and most readily differentiated by an entirely yellow thorax excluding a small medial spot on the anepisternum, and a pale abdomen with tergites 4, 5 and the epandrium dark.

Colouration highly similar to that of Allometopon plicatum is also seen in some A. malayensis ( Figs 173–178 View FIGURES 173 – 183 ), but the arista is short plumose (not pubescent) with at least the basal 1/3 white (not just the base). The genitalia are also quite dissimilar, including the large, clavate distiphallus, which also exhibits sclerotized folds.