Systenus emusorum 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 : 174-176

Systenus emusorum Bickel sp. nov.

( Figs 2 a, b)

Type material. HOLOTYPE ♂, COSTA RICA: Guanacaste: 3 km SE Rio Naranjo, 2—9.III.1992, F.D. Parker ( LACM, ex. EMUS; LACM Ent 329998).

Description. Male: body length: 2.3 mm; wing 2.4 x 0.7 mm ( Fig. 2 a); similar to S. eboritibia except as noted: Head: antenna missing on unique specimen, but scape yellow.

Thorax: metepimeron distinctly yellow. Legs: all coxae and remainder of legs yellow, except distal quarter of FIII and TIII dark brown, CI and CII with white anterior setae and shorter vestiture, CIII with strong while lateral seta at ½; major leg setae black; I: 2.9; 2.8; 1.2/ 0.7/ 0.4/ 0.2/ 0.3; leg I bare of major setation; TI with whitish vestiture on anterior face (MSSC); II: 3.7; 3.9; 2.0/ 1.2/ distal tarsomeres missing; TII with strong ad seta and weaker pd seta at ¼, pd seta only and also ventral seta at 2/3, and with apical ring of ad, pd, av and ventral seta; III: 3.8; 4.3; tarsomeres missing; TIII with 3 black dorsal setae from ¼ to 3/4, and with apical ring of dorsal, ad and av seta. Wing: veins M and R4+5 subparallel (not bowed) beyond dm-cu crossvein; CuAx ratio: 0.8; lower calypter pale yellow with yellowish marginal setae; halter yellow. Abdomen: tergite 1 yellowish; tergite 2 mostly yellow but with some metallic green iridescence; tergite 3 metallic bronze-green dorsally and yellowish lateral; tergites 4–7 mostly metallic green-bronze, shining with little pruinosity; posterior margin of tergite 1 with posterior row of long black setae, tergites otherwise covered with short black vestiture; segment 7 forming relatively shorter peduncle, with sternite 7 glabrous and tergite 7 covered with black vestiture; sternite 8 with white hairs; hypopygium ( Fig. 2 b) dark brown with yellow surstylus and cercus; epandrium projected ventrally and apically downturned; surstylus basally squarish with apical digitiform projection on dorsal margin, and with curved digitiform projection arising dorsobasally; cercus elongate, thick basally, then narrowed and clavate distally, and covered with short yellow setae. Female: unknown.

Remarks. Systenus emusorum is known from a single male taken at the Rio Naranjo site, Costa Rica in the month of March. The antennae are missing on the single known specimen. However, diagnostic characters include all coxae and legs mostly yellow except the distal quarter of both femur III and tibia III which are dark brown, and the metepimeron is yellow. Tibia I has ivory-colored vestiture on the anterior surface.

Etymology. This species is named in honor of the staff at the Entomological Museum, Utah State University (acronym EMUS) for their work in building such a fine entomological collection.

Figures

FIGURE 2. Systenus emusorum sp. nov. (holotype): a. male habitus, left lateral; b. hypopygium, left lateral. S. naranjensis sp. nov. (holotype): c. male habitus, left lateral; d. hypopygium, left lateral; e. male head, anterior.