Protosilvius gurupi

Holotype female. Body length: 8.9 mm. Specimen mostly light yellow. Head (Fig. 1) with eyes black (green in life,) more or less suboval in profile, rounded laterally in frontal view, with very short yellowish bristles which are barely visible under higher magnification. Frons (Fig. 2) narrow, somewhat parallel sided, slightly divergent dorsally and ventrally, frontal index about 2.7, smoothly tomentose, with a median inconspicuous groove, and short, inconspicuous brown bristles. Ocellar tubercle (Fig. 2) somewhat prominent, as high as ocellus. Subcallus (Fig. 2) very small, tomentose, separation from frons indistinct. Parafacial narrow, tomentose, with long black bristles. Face convex laterally, deeply sunken medially, tomentose, without bristles, separate from parafacial by deep groove. Antenna (Fig. 3) with scape and pedicel short, plump, yellow to brown, and with robust black bristles; flagellum light yellow with robust black bristles, apparently with six flagellomeres; postpedicel swollen when observed in lateral view, with three distal flagellomeres, the first flagellomere almost totally fused to postpedicel based on a distinct incomplete suture on medial side (see Fig. 3 from a clarified antenna of a different paratype specimen); second flagellomere as long as first and with an indistinct suture; third flagellomere, the distalmost, longer than two preceding flagellomeres. Palpus (Fig. 4) with first segment somewhat swollen, second slightly narrower and slightly curved, distinctly bristled. Proboscis short, as long as palpi, membranous, with long, narrow, soft and bristled labellum. Thorax with scutum and scutellum light brown to dark yellow, sparsely yellow bristled, with yellow pruinescence. Pleuron slightly clearer than scutum, yellow with light grey to yellow pruinescence. Legs (Fig. 1) entirely yellow except distal half of tarsomeres 5 brown; most legs with yellow bristles, except fore tibia black bristled. All tarsomeres 1 of equal length. Hind tibial spurs slightly shorter than mid ones. Wing (Fig. 5) 9.1 mm long, 2.9 mm wide, narrower than usual for tabanids, diffusely brownish, with costal margin slightly darker; pterostigma ill defined. Vein Sc bare dorsally and ventrally; vein R4 with short appendix; vein CuA1 with even row of small setulae; cell cup open. Halteres with stem yellow and capitulum brown and white. Abdomen (Fig. 1) long, narrow, entirely yellow, with short golden bristles dorsally and ventrally. Terminalia: Tergite 9 (Fig. 6) narrow medially, expanded laterally; tergite 10 subrectangular in dorsal view, divided medially; cercus subtriangular. Sternite 8 (Fig. 7) wider than long, with somewhat distinct gonapophysis. Genital fork as in figure 8. Male. Body length: 9.0 mm; wing length: 9.1 mm. Habitus similar to female specimens except head holoptic, antenna (Fig. 9) slightly weaker, cell cup narrowly open (sometimes narrowly closed, without petiole), abdomen slender and of a lighter tone, first 3–4 abdominal segments light yellow, somewhat translucent, remaining brown. Terminalia (Fig. 10): epandrium with concavity basally; cercus subquadrate in lateral view; gonocoxite slightly arched; gonostylus bifid (Fig. 11); ejaculatory apodeme and gonocoxal apodeme similar in length.

Brazil, Maranhão.