Robustagramma orthogonium Cui and Marshall 2005, new species

Robustagramma orthogonium Cui and Marshall, new species

(Figs. 356–362)

Body length 1.2–1.7 mm. General color pale to dark brown, moderately pollinose, without conspicuous pigmentation.

Head: Face, gena and antenna brownish, lower frons reddish brown, head otherwise dark brown. Interfrontal bristles in 3 pairs. Two orbital bristles, anterior orbital bristle ca. 3/5 as long as posterior. Uppermost orbital setula present between orbital bristles; lower orbital setulae small. Ocellar bristle, inner and outer vertical brsitle, and inner and outer occipital bristle well developed. Postvertical bristle half as long as inner occipital bristle, slightly convergent. Postocellar bristle weak. Facial ridge between antennae over 1.5 times as broad as width of scape. Eye height ca. 2.1–2.2 times genal height. Arista slightly longer than head height. Aristal hairs ca. 2.5 times as long as basal width of arista. Palpus conspicuously thickened, maximum palpal width one­third as long as palpus. Preapical palpal bristles similar in length to maximum width of palpus.

Thorax: Prosternum narrow, bare. Dorsocentral bristles in 2 postsutural pairs, anterior pair slightly longer than middle prescutellar acrostichal bristle. Acrostichal setulae in 8 irregular rows between anterior dorsocentral bristles. One pair of setulae between prescutellar acrostichal and dorsocentral bristle. Apical scutellar bristle ca. 1.7 times length of scutellum. Posterodorsal katepisternal bristle half as long as distance between bristle base and wing base; anterodorsal katepisternal bristles half as long as posterodorsal katepisternal bristle. An additional, small setula frequently present before anterodorsal katepisternal bristle. Halter knob pale brown; stem pale. Wing almost clear. First costal sector, in anterior view, distinctly thicker than second costal sector. Length of second costal sector ca. 0.51–0.54X length of third. Distal 1/3 of R 2+3 slightly curved forward. R 4+5 and costa ending together before wing apex. Discal cell without appendices. Tarsi and fore tibiae yellow, legs otherwise brown. Mid tibia with a long posterodorsal proximal bristle, an anterodorsal bristle near middle, and an anterodorsal, dorsal and posterodorsal distally; dorsal bristle very small. Mid femur with a uniform row of strong anterodorsal setulae, 2 or 3 anterior preapical bristles and one small posterodorsal apical bristle. Mid tibia of male with an apicoventral and several short ventral bristles on distal third; mid femur of male with a row of 5 ventral proximal bristles.

Male abdomen: Sternite 5 nearly twice as long as sternite 4, with a row of dark scales on prominent posteromedial margin. Dorsomedial length of epandrium ca. 0.3X length of sternite 8. Surstylus entirely setose, rectangular in lateral view. Cercus mostly setulose, distinctly shorter than surstylus. Postgonite with 4 tiny setulae on distal half. Ejaculatory apodeme ca. 1/8–1/7 as long as aedeagal apodeme.

Female abdomen: Tergite 10 almost entirely setulose and with 4 small bristles. Sternite 8 reduced to two sclerites. Sternite 10 transverse, setulose. Spermatheca with distal portion larger than basal portion, and with short duct and a few cilia around base.

Holotype (♂, DEBU): PERU: Loreto. Campamento San Jacinto, 175–215m, FIT, 3.vii.1993, R. Leschen.

Paratypes: Same data as holotype, but dated 5.vii.1993 (1 ♀, DEBU) and 7.vii.1993 (1 ♀, DEBU).

Etymology: The specific epithet refers to the rectangular shape of the surstylus in lateral view.