Opeatocerata rubida (Wheeler & Melander)

(Figs 145–151)

Empis rubida Wheeler & Melander, 1901: 368; Melander, 1902: 302 (fig. wing); Bezzi, 1909: 348 (cit.). Opeatocerata rubida: Melander, 1928: 135; Smith, 1967: 18 (cat.); Smith, 1989: 512 (redescription); Yang et al., 2007: 146 (cat.); Cumming & Sinclair, 2009: 668 (cit.); Câmara & Rafael, 2011: 37 (cit.).

Diagnosis. Dark yellow species (Fig. 145) except for brown anterolateral and posterior margins on segments 8 and 10 (Figs 148, 150); fore tarsomeres black (Fig. 147); sternite 8 with anterolateral angles and acute apex brown (Fig. 150); and genital fork with base longer than wide and arms separated at apex (Fig. 149).

Re-description. Female (Fig. 145). Head: Frons dark brown, shiny, as wide as superior margin of the face. Face dark brown, shiny, slightly convergent toward the proboscis, about 2X longer than lower width. Ocellar tubercle dark brown with gray pruinescence; ocelli brown. Antenna brown; postpedicel about 1.5X longer than pedicel; stylus about 2X longer than first flagellomere. Proboscis yellow, slightly longer than head height. Thorax dark yellow, shiny (Fig. 145). Legs predominantly yellow with bristles of varying length; fore tarsi black; hind femur with apical black ring; hind tibia with black distal third, mid and hind legs with apex of tarsomere 1 and tarsomeres 2–5 black (Fig. 147). Wing (Fig. 146) hyaline; pterostigma brown, conspicuously, about 3.5X longer than wide. Halter yellow. Abdomen (Fig. 145) dark yellow, except anterolateral and posterior margins on segments 8 and 10 brown (Figs 148, 150); bristles yellow, longer laterally in all segments and scattered on tergites and sternites 8 and 10. Terminalia: Tergite 8 subrectangular with brown apex and concave posterior margin (Fig. 150). Sternite 8 with wider and concave base and acute apex; anterolateral angle and apex brown (Fig. 150). Genital fork with base longer than wide (Fig. 149); arms separated at apex. Tergite 10 undivided, about half the length of tergite 8 (Fig. 150). Sternite 10 with straight base and slightly bilobed at apex (Fig. 150). Receptacle of spermatheca spherical (Fig. 51). Specimen length: 4.0 mm; wing length: 4.5 mm. Male. Unknown.

Geographical distribution. Mexico (Fig. 211).

Type material. HOLOTYPE ♀, labelled: Mexico, Chilpanchingo, Guerrero, 4600 ft. june. H. H. Smith (BMNH).

Holotype condition. Left ocellar bristle and right antenna lost; left foreleg and right hindleg lost; right wing on microslide and left in plastic tube; abdomen in microtube with glycerin.

Remarks. Opeatocerata rubida differs from all other species that have females known by a combination of the following characters (in parentheses, the states in other species): fore tarsomeres black (only fore tarsomeres 3–5 or 4–5 brown to black), mid and hind legs with apex of tarsomere 1 and tarsomeres 2–5 black (only 4–5 brown to black); sternite 8 with anterolateral angles and apex brown (yellow) and acute apex (rounded); segment 10 brown (yellow).

Comments. Opeatocerata rubida was recorded for Costa Rica (1 ♀) and Panama (1 ♀) by Melander (1928) and Bolivia (2 ♀) by Bezzi (1909). Smith (1989) examined these specimens and noted that they were not O. rubida . Smith (1989) stated that the specimens from Costa Rica and Panama were lighter, smaller, with hyaline, long and narrow wings; the specimen from Costa Rica had a darker abdomen and the one from Panama had abdominal spots. Furthermore, the two specimens from Bolivia did not have spots on the abdomen, had infuscated brown wings, and were more similar to O. lopesi than O. rubida . Therefore, specimens from Costa Rica, Panama and Bolivia are not considered conspecific with O. rubida and consequently the latter species is recorded so far only from Mexico.