Systenus eboritibia Bickel

Bickel, Daniel J., 2015, The Costa Rican Systenus Loew (Diptera: Dolichopodidae): rich local sympatry in an otherwise rare genus, Zootaxa 4020 (1), pp. 169-182 : 178-179

Systenus eboritibia Bickel sp. nov.

( Figs 4 a, b)

Type material. HOLOTYPE ♂, COSTA RICA: Guanacaste: 3 km SE Rio Naranjo, 1—10.VIII.1992, F.D. Parker ( LACM, ex. EMUS). ( LACM Ent 300002).

Description. Male: body length: 2.8 mm; wing 2.7 x 0.8 mm ( Fig. 4 a). Head: head almost circular in anterior view; postcranium dorsally concave; single row of short postorbitals, white with only dorsal setae black, and dorsalmost pair behind ocellar triangle strong; frons, face, dark metallic green with thick brownish pruinosity; clypeus dark blue-green; strong vertical and ocellar setae present; eyes distinctly separated across face; ventral eye facets slightly larger than dorsal facets; palpus yellow with short black setae and strong apical seta; proboscis dark brown, projecting anteriorly, keel-like; antenna dark brown; scape and pedicel short; postpedicel elongate, triangular tapering gradually, covered with short pubescence, about 3 times as long as basal width, and with short apical arista. Thorax: dorsum dark metallic green with bronze reflections and grey pruinosity; pleura green with dense grey pruinosity; posterior third of mesonotum distinctly flattened; thoracic setae black except where noted; 12 pairs of ac with posterior pair bordering mesonotal depression larger and offset laterally; 6 strong dc, decreasing in size anteriorly. Legs: coxae mostly dark brown, but distal eighth pale yellow; all trochanters pale yellow; femora mostly dark brown basally but distal quarter of FI and distal eighth of FII and FIII yellow; tibiae and basitarsus I and III with white cuticle with short ivory colored (not black) vestiture (MSSC); TII pale yellow with brownish vestiture; CI and CII with white anterior setae and shorter vestiture, CIII with strong white lateral seta at ½; major leg setae black; I: 3.5; 3.4;.7/ 0.8/ 0.4/ 0.2/ 0.3; leg I bare of major setation; II: 3.9; 4.2; 2.2/ 1.4/ 0.9/ 0.7/ 0.5; TII with strong ad seta and weaker pd seta at ¼, and strong ad seta and small pd seta at 2/3, and with apical ring of ad, pd, av and ventral seta; III: 4.0; 5.2; 1.0/ 1.6/ 1.0/ 0.6/ 0.5; TIII covered with ivory colored short vestiture (MSSC) and with 4 almost evenly spaced black dorsal setae, and with apical ring of dorsal, ad and av seta. Wing: hyaline; R2+3 and R4+5 diverging, R2+3 joining costa near 7/8, and R4+5 joining costa subapically; veins M and R4+5 diverging in basal portion of wing with two veins slightly bowed half way between dm-cu crossvein and apex and running subparallel to apex, M joining costa just behind wing apex; anal vein and anal cell present; CuAx ratio: 0.7; lower calypter pale yellow with yellowish marginal setae; halter yellow. Abdomen: black with metallic bronze-green reflections and with dusting of grey pruinosity; posterior margin of tergite 1 with posterior row of long black setae, tergites otherwise covered with short black vestiture; sternites 2–6 membranous or only weakly sclerotised, somewhat recessed; sternite 7 glabrous (to be withdrawn between sternites 5 and 6 at rest) and tergite 7 covered with same black vestiture as preabdomen; hypopygium ( Fig. 4 b) dark brown with yellow surstylus and cercus; ventral epandrium prolonged and curved; surstylus basally lobate with some lateral setae and with curved apical dorsal projection (hidden between cerci in Fig. 4 b); cercus elongate, digitiform and slightly expanded distally, and covered with short yellow setae. Female: unknown.

Remarks. Systenus eboritibia is known from a single male taken at the Rio Naranjo site, Costa Rica. It has the diagnostic male characters of a black tapering postpedicel, coxae and femora to femoral knees dark brown, both tibia I and tibia III and basitarsus I and III have white cuticle with short ivory colored (not black) vestiture, and the cercus distally expanded and extending well beyond the surstylus.

Etymology. The specific epithet “ eboritibia ” is from the Latin, eboris, meaning ivory, and refers to the ivory colored male tibia III.

Figures

FIGURE 4. Systenus eboritibia sp. nov. (holotype): a. male habitus, left lateral; b. hypopygium, left lateral. S. parkeri sp. nov.: c. male habitus, left lateral; d. hypopygium, left lateral; e. male postabdomen, right lateral.