Allometopon lunatum, Owen Lonsdale, 2016

Owen Lonsdale, 2016, Revision of the genus Allometopon Kertész (Diptera: Clusiidae), Zootaxa 4106 (1), pp. 1-127 : 38

Allometopon lunatum spec. nov.

Figs 137–142

Description. General: ( Figs 137, 138 ) Body length approximately 2.9mm. Arista short plumose. M1+2 ratio 3.9. First flagellomere subovate, higher than long with dorsum slightly more produced. Female unknown.

Chaetotaxy: Three fronto-orbital setae, anterior seta 2/3 length. Ocellar seta twice length of tubercle. Postvertical seta absent. Interfrontal seta minute. Frons covered with minute setulae. First flagellomere along margins (excluding base) with hairs longer than width of arista base. Anterior dorsocentral half length of posterior dorsocentral; closely set posteriorly; setula in front of anterior dorsocentral enlarged, approximately half length of anterior dorsocentral. Acrostichal seta absent. Two lateral scutellar setae, anterior seta small.

Colour: Setae yellow, brown dorsally on abdomen. Head yellow in ground colour, yellowish-white below antennae; antenna, including basal half of arista yellowish-white; ocellar tubercle dark brown, confluent with one pair of short posterolateral stripes that fade to midpoint of frons and do not extend to eye margin or base of vertical setae; back of head with one pair of stripes radiating from foramen that fuse basally and reach base of vertical setae; parafacial, gena and postgena silvery tomentose. Scutum brown with ventral half of postpronotum and lateral margin of notopleuron light yellow; one pair of narrow, floating, light yellow stripes along dorsocentral row that both end and curve inwards at transverse suture. Scutellum dark brown. Mediotergite brown with venter yellow, anatergite brown and katatergite light yellow. Pleuron and legs yellowish-white. Halter yellow. Wing lightly clouded, becoming clear towards posterior margin. Posterior half of tergite 1 to sternite 8 dark brown dorsally and with thin yellow lateral margin; remainder of abdomen yellow.

Male terminalia: ( Figs 139–142 ) Sternites 6 and 7 weakly sclerotized. Epandrium slightly more pointed and dome-like dorsally. Cerci small, ill-defined, apically convergent. Surstylus relatively small, folded and irregular with small posterobasal lobe, and narrow, inset, anteriorly angled distal lobe; outer surface mostly bare except for long setae along anterior margin and in posteromedial cluster; minute, pointed tubercle-like setae on inner surface of inner-distal and posterobasal lobes. Hypandrium band-like with anterior transverse section broader; arm large and stout with serrated medial ridge; single seta on basal lobe (possibly homologous with pregonite). Phallapodeme broad and plate-like with transverse carina across apical dome. Postgonite slightly longer than wide, tapered apically and with several setae from apex to inner-medial surface. Basiphallus large and well-developed, ending in minute epiphallus. Distiphallus short, narrow and minutely textured. Paraphallus much longer than distiphallus, apically tapered and with dorsal band of long spinules.

Etymology: The specific epithet is from the Latin for “shaped like a crescent moon”, referring to the yellow scutal stripes on the mostly dark notum.

Distribution: Papua New Guinea.

Holotype: PAPUA NEW GUINEA. East Sepik Province: Imbia, near Maprik, 19.xii.1963, D.K. McAlpine (1♂, AMSA).

Comment: Allometopon lunatum and A. tenebrae ( Fig. 269 ) and putatively allied species that are dorsally dark, have a relatively long ocellar seta and generally similar male genitalia, including a convoluted, hooked surstylus, a broad, spinulose wing-like paraphallus and a reduced epiphallus. Allometopon lunatum differs in having an entirely pale first flagellomere (dorsally brown in A. tenebrae ), a paler frons, one pair of short, narrow yellow supra-alar stripes, two small lateral scutellar setae (not one), an entirely pale pleuron (anepisternum at least partially brown dorsally in A. tenebrae ), a yellow katatergite, an anteriorly yellow tergite 1 and an entirely yellow epandrium.

Figures

FIGURES 137 – 142. Allometopon lunatum spec. nov., holotype; 137: photo, dorsal; 138: same, lateral; 139: external genitalia, left lateral; 140: inner surface right surstylus; 141: external genitalia, posterior; 142: internal genitalia, left lateral.

FIGURES 269 – 274. Allometopon tenebrae spec. nov., holotype; 269: photo, dorsal; 270: same, lateral; 271: external genitalia, left lateral; 272: same, posterior; 273: internal genitalia, left lateral; 274: detail of paraphallus and distiphallus, ventral.