Oedematopus vidua Becker 1922
Creators: name: Naglis, Stefan M.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Oedematopus
Oedematopus vidua

description: Oedematopus vidua (Becker, 1922)
(Figs. 1 C, 4)
Liancalus vidua Becker, 1922: 118.
Oedematopus shannoni Van Duzee, 1930: 72. syn. nov. Oedematopus transversus Van Duzee, 1930: 74. syn. nov.
Type material examined. PERU: HOLOTYPE Ψ: [green label:] “ Peru, 5.I.04, Pichis-Weg”, “ Liancalus vidua B. det. Becker”, [red label:] “ Typus Orthoceratium vidua Beck. ”, “ Liancalus Lw. ”, “ vidua Beck. ”, “Staatl. Museum für Tierkunde Dresden”, [green label:] “Coll. W. Schnuse 1911 – 3”, [red label:] “ Holotypus des. U. Kallweit 1991” [MTD]. PARATYPES: PERU: 1 ɗ, “Verrugas Canon, Lima, Peru, 20 May 1928, R. C. Shannon”, [label with red border:] “ Oedematopus shannoni Paratype Van Duzee”. [CAS]; 1 ɗ, “Verrugas Canon, Lima, Peru, 20.5.28, R. C. Shannon”, [label with red border:] “ Oedematopus shannoni Paratype Van Duzee” [BMNH].
Additional material examined. PERU: 1 Ψ Laristhal, 14.VIII.1903, 800- 2000 m. Coll. W. Schnuse 1911 – 3 [head and abdomen missing] [MTD].
Redescription. Male. Length (paratype): body 6.0 mm, wing 6.7 mm; thorax 1.9 mm, abdomen 2.8 mm. Head: Face with dense dark grey pruinosity, with a greenish spot below antennae, ratio narrowest distance between eyes to distance between ocellar setae = 6; ratio height of face and clypeus to narrowest distance between eyes = 1.8; palpus dark with grey pruinosity and dense long brown hairs; antenna dark brown; scape about twice as long as pedicel; pedicel about as long as high; first flagellomere ovate and about as long as high; arista dorsal, bare; frons with dark grey pruinosity and with green spot below ocellus, dark with metallic reflections; pair of relatively short ocellar setae present; upper postoculars short and uniseriate, lower long, white and multiseriate. Thorax: Metallic green ground color of mesonotum covered with dense black pruinosity on anterior part, and with silvery-white pruinosity on area of anterior dc; acrostichal setae absent; 6 dc present decreasing in size anteriad; scutellum with pair of strong marginal setae, and with some smaller additional median setae; pleuron mostly covered with dense grayish pruinosity; propleuron with 1 strong pale seta in addition to pale hairs. Legs: All legs including coxae dark, femora and fore tibia with metallic green reflections; CI with white short hairs and black apical setae; FI with multiseriate ventral row of short spine-like setae along entire length, like members of Hydrophorus, (MSSC; see Van Duzee 1930, plate III, fig. 29); TI with some small dorsal setae, and with ventral minute spine-like setae along entire length, It1 with ventral pile, It2-5 with row of curved minute av/pv setae, It4 with pair of strong flattened apicoventral setae (MSSC; see Van Duzee 1930, plate III, fig. 30); FII with 2 preapical setae; TII with 2 strong ad setae at 1/5 and 2/3, and 2 strong pd setae near base and at 1/2; IIt2-5 with same setation as It2-5 (MSSC; see Van Duzee 1930, plate III, fig. 31); FIII with 2 small preapicals; IIIt4 with pair of flattened apicoventral setae (MSSC; see Van Duzee 1930, plate III, fig. 32). All claws very well developed, pulvilli absent. Relative podomere ratios: I: 46:45:22:8:5:4:10; II: 67:72:35:12:6:5:10; III: 75:82:36:28:10:7:11. Wing: With weak brownish maculation on area of basal section of M (see Van Duzee 1930, plate III, fig. 33); R4+5 only slightly curved posteriad before wing apex; cross-vein dm-cu nearly parallel to posterior wing margin and shorter than distal section of M (Fig. 1 C); RMx ratio: 2.6; CuAx ratio: 5.0; lower calypter pale yellow with fan of yellow setae; halter stem brown, knob yellow. Abdomen: Metallic green, with grey pruinosity; hairs and setae black; sternum 4 forming hood and partially enclosing hypopygium, with tuft of minute spine-like setae. Male genitalia (Fig. 4): epandrial lobe as single arm, swollen apically, with 4 subapical setae; Vsur with 4 subapical setae of different lengths; Dsur slightly curved, with single arm bearing 1 hook-shaped and 1 small seta apically, and with cluster of 3 setae subapically; cercus broad and rectangular. Female: Similar to male, but face broader and lacking MSSC.
Remarks. Becker (1922) described Liancalus vidua and figured the wing. Van Duzee (1930) transferred the species to Oedematopus and in his key he gave a single character for separating O. vidua from its congeners: black coloration of setae on lower calypters. I have examined the female type specimen and observed that these setae are not black but brownish, and regard this coloration as being in the range of intraspecific variation. Since the collecting site is also in Peru, I have no doubt that O. vidua represents the female of O. shannoni. Therefore, I herewith synonymize O. shannoni with O. vidua.
The holotype, allotype and one paratype of O. shannoni at USNM are destroyed (N. Woodley pers. comm.). But I could examine two male paratypes from CAS and BMNH. In describing O. transversus from two females (both types at USNM destroyed, N. Woodley pers. comm.) Van Duzee (1930) justified his new species by the extensive brown pruinosity on face and clypeus in contrast to O. shannoni. But in my examinations of additional material I observed that the brown pruinosity on face and clypeus in females is a variable character in the genus. Moreover, the collecting site and collecting date are identical with that of O. shannoni. Therefore, I regard O. transversus as conspecific with O. shannoni and herewith synonymize both species with O. vidua.
description: Published as part of Naglis, Stefan M., 2011, Revision of the genus Oedematopus (Diptera, Dolichopodidae) with the description of a new genus and a key to the Neotropical genera of Hydrophorinae, pp. 40-52 in Zootaxa 2756 on pages 45-46, DOI: 10.5281/zenodo.201012