Robustagramma acutistylum Cui and Marshall, 2005

Marshall, Stephen A. & Cui, Yongsheng, 2005, Systematics of Robustagramma, a new genus of New World Sphaeroceridae (Diptera), Zootaxa 1026 (1), pp. 1-122 : 107-109

Robustagramma acutistylum Cui and Marshall , new species

( Figs. 335–341 , 377 )

Body length 1.4–1.6 mm. General color brown to dark brown, heavily pollinose but without conspicuous patterns.

Head: Face yellow to brownish; gena, antenna and lower frons yellow to reddish yellow. Frons subshining and flat. Interfrontal bristles in 2 or 3 pairs. Two orbital bristles, anterior orbital distinctly weak, half as long as posterior; uppermost orbital setula present between orbital bristles. Ocellar bristle, inner and outer vertical bristles, and inner and outer occipital bristles well developed. Postvertical bristle half as long as occipital bristle, parallel or slightly convergent. Postocellar bristle distinctly shorter than postvertical bristle or absent. Facial ridge between antennae similar in width to width of scape. Eye height ca. 2.3–2.4 times genal height. Arista slightly longer than head height. Aristal hairs 3 times as long as basal width of arista. Palpus moderately thickened, maximum palpal width ca. 0.3 times as long as palpus. Preapical palpal bristle ca. 1.5 times as long as maximum width of palpus.

Thorax: Prosternum narrow, bare. Dorsocentral bristles in 2 postsutural pairs, anterior postsutural dorsocentral bristles slightly longer than middle prescutellar acrostichal bristles. Acrostichal setulae in 6 rows between anterior dorsocentral bristles. One pair of setulae between prescutellar acrostichal and dorsocentral bristles. Apical scutellar bristle ca. 1.8 times length of scutellum. Posterodorsal katepisternal bristle over half as long as distance between bristle base and wing base; anterodorsal katepisternal bristle absent. Halter knob brown; stem pale yellow. Wing distinctly pigmented, with two transverse, zigzag, clear bands beyond intersection of costa and R 2+3. Costa between humeral and subcostal break thinner than second costal sector in dorsal view (but thicker than second costal sector in anterior view). Length of second costal sector ca. 0.31–0.40X of length of third. R 2+3 distinctly short, distal quarter slightly curved forward. R 4+5 and costa ending together before wing apex. Discal cell without appendices or with a trace of stump vein CuA 1. Tarsi and fore tibiae yellow. Mid tibia with a single posterodorsal proximal bristle, an anterodoral bristle near middle, and an anterodorsal, dorsal and posterodorsal bristle distally; dorsal bristle very small. Mid femur with 2 or 3 anterior subapical bristles and one small posterodorsal apical bristle. Mid tibia of male with an apicoventral and several short, stout ventral bristles on distal third; mid femur of male with 8 ventral proximal bristles in two irregular rows. Male abdomen: Sternite 5 distinctly asymmetrical, twice as long as sternite 4, with a simple posteromedial margin and a black, bare posteromedial area. Dorsomedial length of epandrium ca. 0.3X length of sternite 8. Surstylus pointed apically, with many long bristles. Cercus slightly shorter than surstylus, tapering in lateral view. Distiphallus with a pair of dorsal whip­like sclerites. Postgonite with a slightly­ curved distal half. Ejaculatory apodeme small.

Female abdomen: Tergites 1–6 uniformly pigmented, but tergites 7 and 8 distinctly darker. Sternite 7 rounded posteromedially; sternite 8 reduced to 2 small sclerites. Sternite 10 pale, transverse, setulose. Spermathecae with distal portion much larger than basal portion. Spermathecal duct similar in length to spermathecal body.

Holotype (♂, DEBU) and paratypes (3 ♂, 3 ♀, DEBU): BRAZIL: Paraná. Curitiba , 30 km SE BR277, dung trap, 6–9.ii.1990, S. A. Marshall.

Other paratypes: BRAZIL: Minas Gerais. Tiradentes , pan traps along creek, 15– 17.ii.1990 (1 ♂, DEBU) ; pan/FIT/dung, creek along forest, 20–24.ii.1990, S.A. Marshall (1 ♂, DEBU) ; 1 km E Lavras , in ditch, dung traps, 18–20.ii.1990, S.A. Marshall (2 ♂, 6 ♀, DEBU) . Sao Paulo State. USP Biol. Stn. , human dung, 5–6.ii.1979, R. Woodruff and J. Runnacles (1 ♂, 1 ♀, QBUM) .

Etymology: The specific epithet refers to the distally pointed surstylus.

Figures

FIGURES 335–341. Robustagramma acutistylum sp. nov.: 335, posterior view of male terminalia; 336, lateral view of male terminalia; 337, lateral view of male internal genitalia; 338, male sternite 5; 339, dorsal view of female terminalia; 340, ventral view of female terminalia; 341, spermathecae.

FIGURES 371–378. Robustagramma spp. wings (not to scale): 371, R. biangulatum sp. nov.; 372, R.triangulatum sp. nov.; 373, R. brevicauda sp. nov.; 374, R. cultriforme sp. nov.; 375, R. flavistylum sp. nov.; 376, R. disjunctum sp. nov.; 377, R. acutistylum sp. nov.; 378, R. mirabile sp. nov.