Oscinicita Wheeler

Wheeler, Terry A., 2007, Two new genera of oscinelline Chloropidae (Diptera) from Costa Rica, Zootaxa 1413, pp. 47-53 : 50-51

Oscinicita Wheeler , gen. n.

Type species: Oscinicita hansoni sp. n. (by present designation)

Diagnosis: Minute (1.1–1.2 mm) Oscinellinae with antennae in deep foveae, incurved vibrissal angle and gena, deep postgena, strongly convex scutum, and reduced wing venation (dm-cu absent, CuA1 straight and incomplete, other longitudinal veins short)

Description: Chloropidae , Oscinellinae . Head higher than long in lateral view, with frons strongly sloping toward lunule ( Fig. 8 ), wider than long in dorsal view, with occipital margin concave; frontal triangle distinct, bare except for row of setulae along margin, ocellar tubercle large relative to size of frons; frons with dense interfrontal setulae, fronto-orbital setae in long row barely distinguished from interfrontal setulae, vertical, ocellar and postocellar setae short and weak, ocellar setae reclinate, convergent, postocellar setae convergent; eye rounded, with short ommatrichia; gena incurved ventrally, sparsely setulose, with bare shining strip anteroventral to eye, continuous with shining parafacial; postgena deep and swollen posteroventral to eye, densely tomentose ( Fig. 8 ); vibrissal angle broadly rounded, strongly incurved toward midline of face ( Fig. 9 ), barely visible in lateral view, vibrissa short but distinct; face short, scarcely extending beyond ventral margin of first flagellomere, oral margin high and U-shaped ( Fig. 9 ), face narrow because of incurved vibrissal angle and parafacial, most of face forming deep antennal foveae, facial carina small and narrow in ventral part of antennal foveae; antenna small, only slightly projecting in lateral view, scape and pedicel small, first flagellomere small, rounded, arista short, pubescent; proboscis short; palpus short.

Scutum strongly convex, postpronotum small; scutal setulae evenly distributed, 1–2 postpronotal, 1 anterior and 2 posterior notopleural, 1 postsutural supra-alar, 1 postsutural intra-alar, 1 dorsocentral seta apparently present (setae missing or damaged to some degree in all types); scutellum short, convex, densely tomentose, with short apical, subapical and dorsal setae; subscutellum swollen; thoracic pleurites bare. Wing hyaline, alula small, anal angle well-developed, R2+3 and R4+5 upcurved distally toward C, second costal sector longer than third; M1+2 ending near apex of wing, CuA1 straight, without trace of kink near midpoint, ending well before margin of wing, crossvein r-m present, crossvein dm-cu absent ( Fig. 10 ). Legs without outstanding setae or spurs; femoral organ not evident in type specimens; tibial organ may be present as indistinct, small oval patch (not obvious in all type specimens).

Abdominal tergites with sparse setae laterally and posteriorly, evenly covered with tiny setulae; sternites relatively broad, with sparse setae, abdominal membrane densely spinulose; male spiracles 3–5 in membrane near lateral margin of tergite.

Male postabdomen: dorsal pregenital sclerite narrow; spiracles 6 and 7 in membrane ventral to lateral margin of dorsal sclerite; epandrium simple, convex, with sparse setae; surstylus simple, broadly rounded, freely articulated with epandrium; hypandrium open posteriorly; pregonite fused with postgonite, weakly sclerotized; postgonite with ventral seta and campaniform sensillae; basiphallus elongate, sclerotized, distiphallus short, membranous ( Figs. 11–12 ); phallapodeme simple, phallic guide sclerotized, rounded; cerci small, with triangular ventral points broadly separated across midline, setulose ( Fig. 12 ); subepandrial sclerite well-developed, with sclerotized projection extending dorsally above base of surstylus ( Figs. 11–12 ).

Female unknown.

Etymology: The generic name is derived from oscin - a common generic root in the Chloropidae and -cita, a Spanish term widely used as a diminutive in Costa Rica, referring to the minute size of these flies. The name is treated as feminine.

Remarks: Although the autapomorphic character states of Oscinicita make these flies easily recognizable, they do not resolve the phylogenetic relationships of the genus. The head characters (genal structure, incurved vibrissal angle, short face with distinct antennal foveae) are not informative about relationships. The reduction in wing venation, especially loss of dm-cu, is a homoplasious state, related to small size, in Chloropidae , as well as other acalyptrates, although it occurs more frequently in the subfamily Chloropinae than in Oscinellinae .

Figures

FIGURES 8 – 13. Oscinicita hansoni. 8. head, lateral. 9. head, anterior. 10. wing. 11. male genitalia, lateral. 12. male genitalia, posterior. 13. male genitalia, ventral. Abbreviations: fov — antennal fovea; mem — membranous region ventral to facial margin; ses — subepandrial sclerite. Scale bars = 0.4 mm (Fig. 10), 0.1 mm (Figs. 11 – 13).