Stilobezzia (Acanthohelea) tarsispinosa, 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 : 191-193

Stilobezzia (Acanthohelea) tarsispinosa n. sp. ( Figs. 12–22 )

Diagnosis. Male: the only Neotropical species of Stilobezzia (Acanthohelea) with inner margin of gonocoxite bearing a mesal, short, leaf-shaped projection. Female: the only Neotropical species of Stilobezzia (Acanthohelea) with 2 pairs of spines on tarsomere 5 of fore leg, 3 pairs on mid leg and 1 pair on hind leg.

Male. Head ( Fig. 12 ). Golden brown. Antennal flagellum brown, flagellomeres 11-13 elongate, dark brown; plume dark brown, dense; antennal ratio 0.95–1.02 (0.98, n= 3). Palpus dark brown; segment 3 swollen with subapical rounded pit; palpal ratio 2.00–2.14 (2.08, n= 3).

Thorax. Uniformly dark brown, scutellum with 4 large setae. Legs brown, distal apex of hind femur darker, apex of hind tibia paler, tarsomeres paler; hind tibial comb with 7 spines; prothoracic tarsal ratio 2.00–2.10 (2.07, n= 3) mesothoracic tarsal ratio 2.27–2.30 (2.28, n= 3), metathoracic tarsal ratio 1.80–2.20 (2.03, n= 3). Wing ( Fig. 13 ) length 1.19–1.34 (1.26, n= 3) mm, width 0.40–0.45 (0.43, n= 3) mm, costal ratio 0.73–0.75 (0.74, n = 3); membrane slightly infuscated; second radial cell 2.33–2.67 (2.48, n = 3) X longer than first; cubital fork at level of base of r-m crossvein; macrotrichia on costa, vein R1, sparse on distal margin of cell r3. Halter pale brown.

Abdomen. Dark brown, hairy. Genitalia ( Figs. 14–15 ): tergite 9 extending to apex of gonocoxites, narrowing progressively distad, posterior margin rounded; sternite 9 2.70 X broader than long, with convex posteromedian projection; sternite 10 not clearly distinguishable; cerci slender, curved, divergent. Gonocoxite stout, 1.32 X longer than greatest breadth, inner margin with mesal, short, leaf-shaped projection; gonostylus shorter than gonocoxite, stout, curved, tip blunt. Parameres separated, stout, articulated to sclerotized basal apodemes by two lateral projections; basal portion of stem stout, distal portion swollen with lateral, sclerotized, pointed projection. Aedeagus 0.62 longer than basal breadth, composed by two stout, sinuous sclerites, each with basal portion sclerotized, curved; main portion swollen mesally; distal portion with pointed teeth.

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

Head ( Fig. 16 ). Antennal flagellum dark brown, base of flagellomeres paler; antennal ratio 1.18–1.19 (1.18, n= 2); palpal ratio 2.37–2.50 (2.43, n= 2). Mandible with 6 coarse teeth.

Thorax. Two pairs of spines on tarsomere 5 of fore leg, 3 pairs on mid leg, 1 pair on hind leg ( Figs. 17–19 ); claws of hind legs slightly shorter; prothoracic tarsal ratio 2.10–2.22 (2.16, n= 2), mesothoracic tarsal ratio 2.45–2.50 (2.47, n= 2), metathoracic tarsal ratio 2.30–2.40 (2.35, n= 2). Wing ( Fig. 20 ) length 1.40–1.49 (1.44, n= 2) mm, width 0.52–0.56 (0.54, n= 2) mm, costal ratio 0.77–0.79 (0.78, n = 2); second radial cell 2.10–2.44 (2.27, n =2) X longer than first; scarce macrotrichia on costa, R1, R2, R3, narrow distal margin of cells r3. Halter pale brown.

Abdomen. ( Fig. 21 ). Dark brown; tergites with two small mesal pale spots; sternite 10, cerci, pale yellowish.

Genitalia sternite 8 with anterior margin straight, lateral margins convergent distally, posteromedian excavation Vshaped; sternite 10 with 4 pairs of setae, cerci small; two ovoid spermathecae ( Fig. 22 ) with wide, short necks, measuring 11.40–11.80 (11.60, n = 2) by 6.30–7.00 (6.60, n = 2) µm and 10.30–10.70 (10.50, n = 2) by 5.50–5.90 (5.70, n = 2) µm; plus a small rudimentary third spermatheca.

Distribution. Brazil (Rondônia).

Types. Holotype male labeled, Brazil, Rondônia 62 km SW Ariquemes vic. Rancho Grande, 25-IX-1992,U. Schmitz, UV light trap; allotype female, same data except 20-IX-1992; paratypes 2 males, same data as holotype, 1 female, same data as allotype.

Etymology. The species name tarsispinosa refers to the presence in the female of spines on the tarsomeres 5 of all legs.

Discussion. Stilobezzia (A.) tarsispinosa resembles Stilobezzia (A.) atrichopogon Lane & Forattini by the coloration of the thorax, the number of scutellar setae and the scarce wing macrotrichia. However, the male of S. (A.) atrichopogon is readily distinguished from this new species by the presence of two distal projections on the parameres, while the female has the abdomen entirely dark brown and the spermathecae are smaller.

Figures

FIGURE 12 – 22. Stilobezzia (Acanthohelea) tarsispinosa sp. n., 12 – 15 male; 16 – 22 female; 12 — head, 13 — wing, 14 — genitalia (ventral view), 15 — genitalia scheme, 16 — head, 17 — tarsomere 5 of foreleg, 18 — tarsomere 5 of midleg, 19 — tarsomere 5 of hindleg, 20 — wing, 21 — abdomen (ventral view), 22 — spermathecae. Scale bars: 0, 0 5 mm.