Ommatius prolongatus Scarbrough, 1985

Smit, John T., 2019, Robber flies from Sint Eustatius, Lesser Antilles, with the descriptions of Efferia exaggerata sp. n. and the male of Ommatius prolongatus Scarbrough (Diptera: Asilidae), Zootaxa 4586 (1), pp. 141-150 : 146-147

Ommatius prolongatus Scarbrough, 1985

( Fig. 5 )

Ommatius prolongatus Scarbrough, 1985: 653 ; Papavero 2009: 51.

Specimens examined. 1♀, Botanical garden, 4.x.2015; 2♂ 2♀, De Boven, 6.x.2015, 7.x.2015, 12.x.2015; 1♂ 1♀, De Boven, plot H1, 6.x.2015; 1♂, Oranjestad 4.x.2015, leg. K. Beentjes; 1♂, The Quill NNW, plot M3, 5.x.2015; 1♀, The Quill NW slope, 395 m., 11.x.2015.

Diagnosis. The males of this species are immediately recognized by the thin and long, inwardly curved spine on the apical margin of the epandrium. The females can be recognized by the elongated apical corners of tergite 9.

Description of the male. ( Fig 5 ).

Length, body: 13–15 mm; wing: 10–12 mm. Head. Head and palpi black, face and frons brassy yellow pollinose, occiput gray pollinose. Ocellar and postocular bristles black, as well as the antennal bristles. Face and palpi with pale yellow hairs and bristles. Postpedicel as long as wide, style about twice as long as the three antennal segments combined. Thorax. Dark brown with yellowish pollinosity, mainly confined to the grooves and sides and posteriorly. Scutal bristles black; 2 notopleural, 1 supraalar and 1 postalar and a row of abundant much weaker dorsocentral bristles covering most or nearly the entire length of the scutum. Posteriorly a clutch of weak brown and long hairs in between the dorsocentral bristles. Scutellum entirely light haired, with at most one or two black ones intermixed, and with two thin light brown marginal hairs. Legs. Fore and mid femora in frontal view nearly entirely black, otherwise orange, hind femur basal quarter to third orange, otherwise black. Tibia all primarily orange, with an apical black ring, on hind tibia almost twice as big as in other tibia. All tarsi black, with the basitarsus basally orange. Bristles on hind femur see figure (5E). Wing. ( Fig. 5B ). Slightly infuscated in the apical half; cell br, bm and cup entirely bare of microtrichia, cells m3 and d bare except for the apical part, rest of cells all covered in microtrichia. Cell d widened apically, therefore crossvein m-m shorter than the base of M 2, giving cell d a characteristic shape. Costal margin strongly dilated. Abdomen. Slightly constricted, brown with orange brown hairs, except for the apical 3 segments which are predominantly black haired dorsally. Terminalia. ( Figs. 5D, 5F ). Dark brown, lighter brown ventrally in some specimens. Epandrium swollen and with a thin long, inwardly curved spine on the apical margin. Gonocoxite bearing a short, sharp tooth-like projection, gonostylus long, as long as gonocoxite, and slightly bent, blunt distally.

Distribution. Hitherto known only from the female holotype from Montserat. The discovery of this species on St. Eustatius means that its occurrence on Saint Kitts & Nevis is highly likely, and perhaps a wider distribution in the northern parts of the Lesser Antilles.

Figures

FIGURE 5. Ommatius prolongatus Scarbrough. Male. A: lateral view. B: left wing of male, horizontally flipped. C: dorsal view. D: terminalia, ventral view. E: hind femur. F: terminalia, dorsal view.