Stilobezzia (Acanthohelea) longiradix, Cazorla, Carla G. & Spinelli, Gustavo R., 2016

Cazorla, Carla G. & Spinelli, Gustavo R., 2016, Two new species of the subgenus Acanthohelea of Stilobezzia from Brazilian Amazonia (Diptera: Ceratopogonidae), Zootaxa 4066 (2), pp. 189-193 : 189-191

Stilobezzia (Acanthohelea) longiradix n. sp. ( Figs. 1–11 )

Diagnosis. Male: the only Neotropical species of Stilobezzia (Acanthohelea) with inner margin of gonocoxite bearing a mesal, conspicuous, curved projection with sclerotized tip which is directed anteriorly. Female: the only Neotropical species of Stilobezzia (Acanthohelea) with distal pair of slender spines on tarsomere 4 of all legs.

Male. Head ( Fig. 1 ). Dark brown. Antennal flagellum dark brown; plume brown, well developed; antennal ratio 1.13. Palpus dark brown; segment 3 long, with subapical, rounded sensory pit; palpal ratio 2.50.

Thorax. Uniformly dark brown, scutellum with 6 large setae. Legs yellowish brown; coxae dark brown, hind leg darker except tarsomeres paler; hind tibial comb with 8 spines; basal spine on tarsomere 1 of mid leg; prothoracic tarsal ratio 1.70; mesothoracic tarsal ratio 2.21, metathoracic tarsal ratio 1.86. Wing ( Fig. 2 ) length 1.55 mm, width 0.48 mm, costal ratio 0.77; membrane slightly infuscated; second radial cell 3.30 X longer than first; cubital fork at same level of base of r-m crossvein; macrotrichia on costa, vein R1, abundant on distal narrow margin of cell r3, few on margin of cell m1. Halter pale brown.

Abdomen. Dark brown. Genitalia ( Figs. 3–4 ): tergite 9 extending to 0.90 of gonocoxites length, narrowing progressively distad, posterior margin rounded; sternite 9 7.5 X broader than long, posteromedian excavation concave, deep; sternite 10 wide, produced beyond base of cerci; cerci stout, subparallel. Gonocoxite ( Fig. 5 ) 1.70 X longer than greatest breadth, inner margin with conspicuous, stout, curved, directed anteriorly projection with sclerotized tip; gonostylus slightly shorter than gonocoxite, nearly straight, tip blunt. Parameres ( Fig. 6 ) separated, subparallel, articulated to slender basal apodemes; stem reaching 1/2 the length of gonocoxites, slightly curved, rod-like, tip curved ventrally. Aedeagus ( Fig. 7 ) 0.45 longer than basal breadth, composed by two sinuous, convergent sclerites, each with mesolateral triangular lobe, subapical short pointed projection, tip pointed.

Female. Similar to male, with the following notable differences:

Head ( Fig. 8 ). Antennal flagellum dark brown, base of flagellomeres slightly paler; antennal ratio 1.16; palpal ratio 2.90. Mandible with 7 coarse teeth.

Thorax. Tarsomere 4 of all legs with distal pair of slender spines; prothoracic tarsal ratio 2.42; mesothoracic tarsal ratio 2.70; metathoracic tarsal ratio 2.10. Wing ( Fig. 9 ) length 1.60 mm, width 0.44 mm ¸ costal ratio 0.76; second radial cell 4 X longer than first; cubital fork slightly distal to base of r-m crossvein; macrotrichia on costa, veins R1, R2, R3, abundant on distal 1/3 of cells r3 and apex of m1.

Abdomen. ( Fig. 10 ). Genitalia: sternite 8 apparently rounded, posteromedian excavation U-shaped, sternite 10 with 4 pairs of setae; cerci short, rounded; two subequal, ovoid, spermathecae ( Fig.11 ) with wide, short necks, measuring 7.00 by 4.20 µm and 6.40 by 3.60 µm, plus a rudimentary third spermatheca.

Distribution. Brazil (Rondônia).

Types. Holotype male labeled, Brazil, Rondônia 62 km SW Ariquemes vic. Rancho Grande, 1-V-1992,U. Schmitz, UV light trap; allotype female same data except 12-IX-1992.

Etymology. The species name longiradix refers to the long, curved and conspicuous projection present on inner mesal margin of gonocoxite.

Discussion. Stilobezzia (Acanthohelea) longiradix is similar to the Neotropical species Stilobezzia (A.) paranaense Cazorla & Spinelli from Paraguay and northeastern Argentina. However, the protuberance on the gonocoxite of the male of the latter species is shorter and directed anteromesally, and the female of S. (A.) paranaense has a yellowish scutum with only four setae.

Figures

FIGURE 1 – 11. Stilobezzia (Acanthohelea) longiradix sp. n., 1 – 7 male; 8 – 11 female; 1 — head (dorsal view), 2 — wing, 3 — genitalia (ventral view), 4 — genitalia (dorsal view), 5 — scheme of gonocoxite, 6 — scheme of parameres, 7 — scheme of aedeagus, 8 — head, 9 — wing, 10 — abdomen (ventral view), 11 — spermathecae. Scale bars: 0, 0 5 mm.