Planinasus xanthops, Mathis, Wayne N., Rung, Alessandra & Kotrba, Marion, 2012

Mathis, Wayne N., Rung, Alessandra & Kotrba, Marion, 2012, A revision of the genus Planinasus Cresson (Diptera, Periscelididae), ZooKeys 225, pp. 1-83 : 39-41

9. Planinasus xanthops sp. n. Figures 48-52

Description of male.

Moderately small to medium-sized flies, body length 2.10-3.05 mm.

Head: Head ratio 0.56-0.58; frons mostly bare of microtomentum, subshiny to shiny, except for densely microtomentose, anterolateral angles and undercut anterior margin, blackish brown; frons much wider than long, frontal ratio 0.36-0.39; interfrontal seta long, length subequal to that of lateral vertical seta. Antenna yellow; pedicel with ventral projection long, about 1/2 length of basal flagellomere; basal flagellomere long, about twice height at base; arista bearing 13-14 dorsal rays, 3-4 ventral rays; pedicel bearing 1 dorsoapical seta and 1 dorsal seta. Face generally yellow; very wide, facial ratio 0.69-0.73; dorsad of transverse carina wide, shield-like, medial portion in some specimens faintly brownish yellow, very sparsely microtomentose with some silvery white microtomentum; ventral portion of face yellow, sparsely microtomentose, somewhat seriaceous; large facial setae in 2-3 transverse rows; dorsal row with porrect medial pair of setae, next laterally a large, dorsoclinate seta; ventral row with a ventroclinate seta immediately ventrad of dorsoclinate seta, then with 2 smaller, ventroclinate setae. Clypeus yellow to brownish yellow; palpus yellowish brown. Gena concolorous with ventral 1/3 of face.

Thorax: Generally dark colored, black to blackish brown, anepimeron paler, brownish, with ventral margin yellowish; mesonotum thinly invested with microtomentum, appearing subshiny, with slightly metallic brown luster medially, becoming more steel blue laterally; postpronotum dark brown; area from postpronotum and extended through notopleuron mostly bare, shiny; anepisternum thinly invested with microtomentum, mostly appearing dull, grayish brown; other pleurites less densely invested. Wing conspicuously and uniformly infumate, brownish, base slightly paler, more hyaline. Coxae, trochanters, and base of femora yellow; remainder of femora and tibiae brownish black; forefemur with a preapical, whitish to yellowish partial annulus; basitarsomeres yellow; remaining tarsomeres becoming darker with apical 1-2 dark brown; forefemur with posteroventral surface bearing 1 large seta at apical 1/3.

Abdomen: Uniformly blackish brown to black, mostly shiny, very sparsely invested with microtomentum. Male abdomen: Tergites 1+2-6 well developed, lengths of tergites 3-6 subequal; tergite 7 narrow; sternites 3, 4, 5 generally as rectangular plates, slightly wider than long, lateral margins shallowly arched; sternite 5 with posterior margin of sclerotized portion shallowly arched posteriorly, bearing medially a patch of 10-12 setulae; no sternites 6, 7, neither segment forming an annulus. Male terminalia (Figs 48-51): Epandrium in lateral view (Fig. 48) higher than wide, anterior margin nearly straight, posterior margin irregularly arched, dorsal portion nearly straight, thereafter ventrally recurved to surstylar base, dorsal margin short, length about equal to surstylar width at base, truncate; surstylus length a little longer than half length of epandrium, extended from ventroposterior margin of epandrium in nearly oblique alignment with it, in lateral view (Fig. 48) triangular, tapered to narrow apex, anterior margin nearly straight, posterior margin shallowly sinuous, bearing 1 large, basal seta; hypandrium in ventral view (Fig. 49) more or less V-shaped, arms at attachment with epandrium thin, becoming gradually and slightly thicker toward anterior margin, anterior margin angulate, pointed; pregonite in ventral view (Fig. 49) roughly triangular, with anterior and lateral margins receded and slightly round corners; postgonite in ventral view (Fig. 49) convoluted, with lobe bearing setulae, especially at apex, in lateral view (Fig. 51) irregularly, bearing finger-like lobe with 4 apical setulae; phallus in ventral view (Fig. 49) complex, partially sclerotized, in lateral view (Fig. 51) difficult to discern; phallapodeme in lateral and ventral views (Figs 49, 51) elongate, tubular, nearly straight, in ventral view very gradually tapered to acute point, in lateral view (Fig. 51) parallel sided, truncate apically; ejaculatory apodeme short, length subequal to 1/4 length of phallapodeme, thickened basally, tapered to thin, sinuous apical half without expansion.

Description of female.

Same as male except as follows: Head: Head generally narrower; head ratio 0.69; frontal ratio 0.49; antenna black; dorsad of facial carina blackish brown; ventrad of facial carina yellowish; facial ratio 0.38.

Thorax: Forefemur lacking preapical annulus.

Type material.

The holotype male is labeled "ECUADOR. Prt.Or[e]ll[a]na: RioTiputini (0°38.2'S, 76°8.9'W)[,]12-26Aug1999,W.N.Mathis, A. Baptista, M. Kotrba/USNM ENT 00118278 [plastic bar code label]/HOLOTYPE ♂ Planinasus xanthops Mathis & Rung USNM [red]." The holotype is double mounted (minuten pin in a plastic block), is in excellent condition, and is deposited in the USNM. Four paratypes (3♂, 1♀; USNM) bear the same label data as the holotype.

Type locality.

Ecuador. Orellana: Rio Tiputini Biodiversity Station (0°38.2'S, 76°8.9'W).

Distribution

(Fig. 52). Neotropical: Ecuador (Orellana).

Etymology.

The specific epithet, xanthops, is of Greek derivation, meaning yellow face, and refers to yellow face and antennae of males.

The nigritarsus group

Included species. Planinasus argentifacies sp. n., P. insulanus sp. n., P. nigritarsus sp. n.

Diagnosis. This species group is distinguished by the following combination of characters: Head: Interfrontal seta long, subequal to length of lateral vertical seta. Antenna yellow to yellowish orange with some blackish coloration dorsally; pedicel with short ventral projection; basal flagellomere long, length nearly twice height. Large facial setae arranged in a single transverse row of about 8 setae; face of females somewhat bulbous, evenly transversely arched, mostly black dorsally, densely silvery white, microtomentose ventrally. Thorax: Anepisternum with 3-4 small setae along posterior margin. Wing moderately to strongly infumate. Forefemur of male lacking a pale, irregular, subapical annulus, bearing 1 large, posteroventral seta at apical 1/3. Abdomen: Surstylus generally bearing a basal process and generally in nearly oblique alignment with epandrium; postgonite with robustly developed lobe bearing numerous setulae apically; phallus mostly sclerotized, convoluted; ejaculatory apodeme generally well-developed, at least as long as phallapodeme, with expanded apex.

Discussion. Species of this species group share, with species of the ambiguus group, and only with them, a postgonite with a robustly developed lobe that bears numerous setulae. In other species of Planinasus , the lobe of the postgonite, which is generally less well developed, bears fewer than four apical setulae, and fewer than six setulae overall. The nigritarsus and ambiguus groups also share an ejaculatory apodeme that is generally well developed, at least as long as the phallapodeme, but this character state is also present in Planinasus mcalpineorum sp. n. (the nigrifacies group). The presence of a basal process on the surstylus that bears a setula distinguishes the nigritarsus group from most other groups of Planinasus , but it is also present in Planinasus kotrbae .