Setacera trichoscelis Mathis

Mathis, Wayne N. & Marinoni, Luciane, 2016, Revision of Ephydrini Zetterstedt (Diptera: Ephydridae) from the Americas south of the United States, Zootaxa 4116 (1), pp. 1-110 : 105-107

33. Setacera trichoscelis Mathis

Figs. 146–150 , Map 33

Setacera trichoscelis Mathis 1982b: 53 .— Mathis and Zatwarnicki 1995: 254 [world catalog].

Diagnosis. This species closely resembles S. pacifica (Cresson) and S. needhami Johannsen. The latter two, however, are known only from the Nearctic Region. Specimens of S. trichoscelis may be distinguished from those of either congener by the following characters: supraspiracular convexity shallowly rounded; tufts of hair near the apex of the mid- and hindtibiae well developed, as in members of S. needhami ; and conformation of structures of male terminalia distinctive, particularly the shape of the fused surstyli. Medium-sized to moderately large shore flies, body length 3.20–4.20 mm; mostly subdued, microtomentose, pale brown to grayish green except for subshiny to shiny dorsum.

Head ( Fig. 146 ): Head ratio 0.70; frontal ratio 0.49; frons and fronto-orbits distinctly shiny with metallic blue to greenish blue luster; frons with sparsely scattered, hairs, appearing pilose; ocelli in isosceles triangle, distance between posterior pair shorter than between medial ocellus and either posterior ocellus. Antenna unicolorous, blackish brown, dull, microtomentose with grayish vestiture; basal flagellomere slightly longer than combined length of scape and pedicel; pedicel with some greenish color ventrally. Face mostly silvery white except dorsal shelf; antennal groove and interfoveal space with metallic luster similar in color to mesofrons; area immediately surrounding base of antenna with golden brown microtomentum; lower portion of face receding; facial angle approximately 90° from profile view; length of lower portion longer than distance between base of antenna to facial angle. Eye width-to-height ratio 0.92, oval, orientated at oblique angle to plane of epistoma. Gena wide, gena-to-eye ratio 0.43; concolorous with face, becoming duller posteriorly and with some grayish green to olivaceous coloration.

Thorax ( Fig. 147 ): Mesonotum mostly brown to greenish brown; anterior portion more subdued, microtomentose, grayish brown, darker posteriorly, shinier, metallic green; scutellum with mostly greenish to bronzish blue metallic luster shiny through darker brown vestiture. Anepisternum, anepimeron, and katepisternum mostly concolorous, grayish golden brown to olivaceous; forecoxa shiny gray; meron mostly gray to palely olivaceous in color. Femora mostly gray but with some bluish or pale brown coloration, becoming darker apically; tibiae mostly concolorous with femora but with less grayish coloration; tarsi yellowish orange but with some blackish coloration; legs of males with tufts of long hairs near apices of mid- and hindtibiae; posteroventral surface of midfemur with distinct row of setae which become larger toward base. Costal vein ratio 0.30; M vein ratio 0.83.

MAP 33. Distribution map for Setacera trichoscelis Mathis.

Abdomen: Dorsum mostly unicolorous, brown with metallic bluish green to green luster; tergite 1 more microtomentose, grayish, other tergites becoming darker and shinier posteriorly but not as dark as dorsum of scutellum. Tergite 5 of male longer than wide, nearly as long as combined length of tergites 3 and 4; lateral margins tapered gradually to subtruncate apex. Epandrium of male terminalia triangular, becoming wider toward venter; surstyli attached to ventral margin of epandrium, broadly fused to form subrectangular plate with ventrolateral, rounded processes; sternite 5 loosely attached to posteroventral corners of epandrium, anterior ends produced into gently-curved, well-sclerotized, sickle-like processes; see Figs. of terminalia for further details ( Figs. 148–150 ).

Type material. The holotype male is labeled “Yaguarcocha, 3 km N. Ibarra, 1950 m, Imbabura, Ecuad[or], 8– 9. VI. 65 [8–9 Jun 1965], L. Pena/ Holotype Setacera trichoscelis Mathis [red].” Female allotype and 36 paratypes (10Ƌ, 26♀) are labeled with same label data as the holotype. The holotype, allotype, and most of the paratypes are in the CNC (15239). Two pairs of male and female paratypes are in the USNM.

Type locality. Ecuador. Imbabura. Yaguarcocha (3 km N Ibarra; 0°22'S, 78°06'W).

Additional specimens examined. ECUADOR. Imbabura: Laguna San Pablo (0°12.1'S, 78°14.1'W), 28 Aug 1999, W. N. Mathis (7♂, 2♀; USNM).

PERU. Lima: Lima, Laguna de Villa (12°00.2'S, 76°38.3'W), 14 Feb 1984, W. N. Mathis (9♂, 5♀; USNM).

Distribution (Map 33): Neotropical: Ecuador (Imbabura). Peru (Lima).

Remarks. This species is similar and apparently closely related to S. pilicornis and reference to structures of the male terminalia may be needed to distinguish between them.

Figures

FIGURES 146 – 147. Setacera trichoscelis Mathis. (146) head, lateroblique view; (147) mesonotum, dorsal view (from Mathis 1982).

FIGURES 148 – 150. Setacera trichoscelis Mathis. (148) male terminalia, lateral view; (149) internal structures of male terminalia, lateral view; (150) surstyli, posterior view (from Mathis 1982).