Opeatocerata Melander

Opeatocerata Melander, 1928: 135 . Type species: Empis rubida Wheeler & Melander, 1901: 368 (original designation); Smith, 1967: 18 (cat.); Smith, 1989: 512, 513 (re-description); Yang et al., 2007: 146 (cat.); Cumming & Sinclair, 2009: 661 (key to genera), 668 (cit.); Câmara & Rafael, 2011: 37 (cit.).

Re-description. Male. Head: Holoptic, upper ommatidia larger and clearly delineated from lower ommatidia. Ocellar tubercle protuberant, brown with brown pruinescence, with 2 pairs of divergent bristles, anterior pair longer. Postocular bristles black, distinct, arranged in a complete uniseriate row, progressively longer ventrally. Postcranium brown with grey pruinescence, denser ventrally. Postgena with long yellow bristles. Antenna (Fig. 1) inserted below middle of head; small antennal segments, slightly pubescent, postpedicel suboval; style aristiform, bi-segmented, 2– 3 X longer than postpedicel. Proboscis yellow, labellum with yellow bristles apically and ventrally. Thorax distinctly convex, shiny, with yellow bristles. Pronotum with transverse row of yellow bristles on anterior margin. Thoracic chaetotaxy: 1 acrostichal placed posteriorly, near scutellum and between last and stronger dorsocentral; dorsocentral row of uniseriate, slender, yellow, interrupted on posterior descendant region and posteriorly with pair longer; 3–5 postpronotals; 2 robust notopleurals with several smaller in front; several supraalar; 2 postalar, posterior stronger; 1 pair of parallel scutellars; laterotergite with 7–9 long and yellow bristles. Legs long, slender, mostly yellow, except tarsomeres 4–5 brown to black. All legs with distinct bristles; hind legs with distinct anterodorsal and posterodorsal rows of long bristles; hind tibia with larger number of scattered bristles. Wing (Fig. 2) hyaline with pterostigma brown to black, distinct; Costal vein ending at the apex of the wing; R1 vein ending near the middle of the wing; subcostal vein straight; R4+5 forked, with R5 ending at wing apex and R4 curved upwards, forming angle of almost 90° with R5; cells bm and br shorter than cell dm, cell dm with three branches (M1, M2 and CuA1) with M1 curved upwardly; alula with long bristles. Halter yellow. Abdomen yellow, tergites usually with paramedian brown to black spots (Fig. 3); bristles present laterally in all segments and posteriorly on segments 6–8; sternite 8 divided in two plates (Fig. 4) (except in O. cylindrophallus sp.nov.). Terminalia yellow; epandrium membranous anteriorly, strongly fused to cercus and with posterior ventral lobe (Fig. 5). Cercus divided in two lobes, anterior and posterior (Fig. 6); anterior cercus with dorsal projection and a descendant plate (Fig. 7); posterior cercus usually with dorsal projections. Hypoproct present (Fig. 7). Hypandrium membranous and surrounding phallus. Phallus long and slender, curved upwards, or short and stout. Ejaculatory apodeme tetralamellar. Female similar to male, except dichoptic, with subequal ommatidia; wing usually more infuscated at apex. Abdominal segment 8 elongated and segment 10 shorter than segment 8, cercus long and narrow.

Geographic records. Brazil (Amazonas; Goiás, new record; Mato Grosso; Pará, new record; Roraima, new record); Bolivia (Smith 1989, 2 ♀ not examined); Colombia, new record; Costa Rica, Ecuador, Mexico, Panama (Smith 1989, 1 ♂, 1 ♀ not examined), Trinidad.