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.