Systenus tenorio 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 : 171-172

Systenus tenorio Bickel sp. nov.

( Figs 1 a, b)

Type material. HOLOTYPE ♂, COSTA RICA: Guanacaste: 3 km SE Rio Naranjo, 3—8.V.1992, F.D. Parker ( LACM, ex. EMUS; LACM Ent 329994).

Description. Male: body length: 2.5 mm; wing 2.4 x 0.7 mm ( Fig. 1 a). Head: head almost circular in anterior view; postcranium dorsally concave; single row of postorbitals, black dorsally, and white ventrally, with dorsalmost pair behind ocellar triangle strong; frons, face, dark metallic green with thick brownish pruinosity; strong vertical and ocellar setae present; eyes distinctly separated across face; ventral eye facets slightly larger than dorsal facets; palpus brown with short black setae and strong apical seta; proboscis dark brown; antenna dark brown; scape and pedicel short; postpedicel triangular and tapering gradually, more than twice as long as basal width, covered with short pubescence, and with short subapical arista. Thorax: dorsum dark metallic green with bronze reflections over ac band, and covered with grey pruinosity; pleura including metepimeron green with dense grey pruinosity; posterior third of mesonotum distinctly flattened; thoracic setae black except where noted; some 12 pairs of ac with posterior pair bordering mesonotal depression larger and offset laterally; 6 strong dc, decreasing in size anteriorly. Legs: CI brown basally but pale yellow on distal half; CII and CIII mostly dark brown but distal third pale yellow; all trochanters pale yellow; FI and FII mostly dark brown but with distal quarter yellow; FIII basally yellow and distal two-thirds to quarter brown to apex; TI and It tarsus ivory-colored; TII and IIt yellow, but distal tarsomeres infuscated; TIII brown but yellowish basally; IIIt mostly brown; CI and CII with white anterior setae and shorter vestiture, CIII with strong brown lateral seta at ½; major leg setae black; I: 3.1; 3.0; 1.3/ 0.7/ 0.6/ 0.3/ 0.2; leg I bare of major setation; TI and tarsus I covered with short white (not black) vestiture (MSSC); II: 3.4; 3.8; 2.0/ 1.1/ 0.8/ 0.5/ 0.4; TII with strong ad seta and weaker pd seta at ¼, ad seta at 2/3, with apical ring of ad, av and pv seta; III: 3.8; 4.7; 0.9/ 1.5/ 0.9/ 0.5/ 0.4; TIII with 5 evenly spaced black dorsal setae from 1/5 to 4/5, 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 subapically; vein M diverging from R4+5 with two veins very slightly bowed half way between dm-cu crossvein and apex, and with M joining costa just behind wing apex; CuAx ratio: 0.5; lower calypter pale yellow with yellowish marginal setae; halter yellow. Abdomen: metallic bronze-green 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; segment 7 forming elongate peduncle; hypopygium ( Fig. 1 b) dark brown with yellow surstylus and cercus; hypandrium as large hood over epandrium with basally projecting extensions and bearing lateral row of 3 setae; phallus hooked and enclosed by hypandrium; short epandrial lobes present, with strong apical and weaker seta arising midlength; surstylus not solidly fused to epandrium, but with line of weakness at base; in lateral view, surstylus subrectangular and distally forked with two elongate digitiform projections separated by broad U-shaped excavation, and each projection bearing apical setae, and with curved digitiform medio-dorsal digitiform projection with short apical seta; cercus elongate and digitiform, with yellow setae. Female: unknown.

Remarks. Systenus tenorio is known from a single male taken at the Rio Naranjo site, Costa Rica, in May. It has the diagnostic male character of black tapering postpedicel (similar to S. eboritibia ), femora I and II brown basally but yellow distally, whereas femur III is yellow in the basal third and brown distally. Tibia and basitarsus I are ivory colored with white vestiture.

Etymology. The specific epithet “ tenorio ” is the name of the nearby Vulcan Tenorio , and should be considered as a noun in apposition.

Figures

FIGURE 1. Systenus tenorio sp. nov. (holotype): a. male habitus, left lateral (terminalia removed); b. hypopygium, left lateral. S. flavifemoratus sp. nov. (holotype): c. male habitus, right lateral; d. hypopygium, left lateral. S. maculipennis sp. nov.: e. male habitus, left lateral (terminalia removed); f. hypopygium, left lateral. Abbreviations: cer, cercus; epan, epandrium; hyp, hypandrium; ph, phallus; st, sternite; sur, surstylus; tg, tergite; 6, 7, 8, abdominal segments.