Stilobezzia (Acanthohelea) estepae Cazorla and Spinelli, 2014

Cazorla, Carla G. & Spinelli, Gustavo R., 2014, A revision of the Patagonian predaceous midges of the subgenus Acanthohelea of Stilobezzia excluding the S. (A.) edwardsi group (Diptera: Ceratopogonidae), Journal of Natural History 49 (3), pp. 155-209 : 164-166

Stilobezzia (Acanthohelea) estepae Cazorla and Spinelli sp. nov.

( Figures 2 , 20 )

Diagnosis

The only Patagonian species of Stilobezzia (Acanthohelea) with wings in which the rm crossvein is interrupted at mid portion and the hind femur is dark brown with pale narrow base. Males tergite 9 with a distomesal, rounded and hyaline protuberance. Females scutellum pale brown with 8 large and 8 thinner setae and mandible with 6 large, coarse teeth.

Male. Head ( Figure 2A ). Dark brown. Antennal flagellum brown, plume brown, moderately developed; antennal ratio 0.95–1.11 (1.01, n = 8). Palpus brown, segment 3 as long as 5; palpal ratio 3.29–4.60 (3.39, n = 8).

Thorax ( Figure 2B ). Dark brown, humeral pits pale brown; scutellum pale brown with 8 stout, 6 thinner setae. Legs brown, hind leg darker, narrow base of hind femur dark brown with pale basal ring; hind tibia dark brown; hind tibial comb with 10 spines; prothoracic TR 1.80–2.07 (1.97, n = 8); mesothoracic TR 2.06–2.29 (2.20, n = 8); metathoracic TR 1.93–2.15 (2.01, n = 8). Wing ( Figure 2C ) length 1.86–2.05 (1.94, n = 8) mm; width 0.60–0.70 (0.65, n = 8) mm; costal ratio 0.65–0.73 (0.70, n = 8); membrane slightly infuscated, r-m crossvein interrupted at mid portion; second radial cell 4.00–2.40 (3.12, n = 8) × longer than first; cubital fork originating at level of base of r-m cross vein; macrotrichia on costa, R 1, R 2, R 3, M 1, distal margin of cell r 3, sparse on distal margin of cell m 1. Halter pale.

Abdomen. Dark brown. Genitalia ( Figure 2D ): tergite 9 extending 0.80 of gonocoxite length, narrowing distad; posterior margin rounded with small, rounded, hyaline, apical protuberance; sternite 9 six times broader than long, with broad, Vshaped posteromedian excavation; sternite 10 stout, produced beyond base of cerci; cerci slender, tapering to tip, divergent. Gonocoxite stout, 1.37× longer than greatest breadth; gonostylus stout, nearly straight, narrowing slightly distally to pointed tip. Parameres subparallel, basal apodemes slightly curved; stem straight, proximal 2/3 slender, distal 1/3 oar-shaped. A small triangular sclerite located at proximal 1/3 of stem of parameres. Aedeagus 0.42× length of basal breadth, composed of two slender, sinuous sclerites, the tips of which are pointed, closely approximated and overlapping in some specimens.

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

Head ( Figure 2F ). Antennal ratio 1.50; palpal ratio 3.14. Mandible with 6 coarse teeth.

Thorax. Scutellum with 8 large, 8 thinner setae. Tarsomere 1 of mid leg with basal stout spine; prothoracic TR 2.00; mesothoracic TR 2.14; metathoracic TR 2.07. Wing ( Figure 2G ) length 2.05 mm, width 0.84 mm, costal ratio 0.73; second radial cell 2.65× longer than first; macrotrichia on costa, R 1, R 2, R 3, M 1, M 2, abundant on distal 1/2 of cell r 3 (distal portion of membrane broken in the available specimen).

Abdomen. Dark brown. Genitalia ( Figure 2H ): sternite 8 with anterior margin convex, lateral margins convergent; posteromedian excavation V-shaped; sternite 10 with 4–5 pairs of setae; cerci elongated; two ovoid spermathecae, with narrow necks, measuring 13 by 8.10 µm and 9.20 by 6.30 µm; plus a small third rudimentary spermatheca.

Distribution

Argentina, only known from its type locality in Río Negro province ( Figure 20 ) .

Types

Holotype male, allotype female, Argentina, Río Negro prov., Paraje Chasicó, Vertiente , 41°08 ′ 28.0 ″ S, 67°35 ′ 43.9 ″ W, 961 m, 6 December 2006, G. Spinelli, CDC light trap ( MLPA). Other paratypes: 8 males, as follows: 7 males, same data as holotype (one in CNCI, one in BMNH, one in USNM); 1 male, same data except sweep net.

Etymology

The name estepae refers to the fact that this is the only species of the subgenus inhabiting the Patagonian steppe.

Discussion

This species is somewhat similar to S. (A.) megatheca . However, females of that species differ by their greatly elongated, flask-shaped spermathecae, and males have an anteromesal pointed tubercle on the inner margin of gonocoxite and a gonostylus with dorsal subapical bulk.

Figures

Figure 2. Stilobezzia (A.) estepae Cazorla and Spinelli sp. nov.: (A–E) male; (A) head; (B) thorax (lateral view); (C) wing; (D) genitalia (ventral view); (E) aedeagus and parameres removed. (F–H) female; (F) head; (G) wing; (H) genitalia. Scale bars 0.05 mm.

Figure 20. Distribution of Stilobezzia (A.) longisternalis, Stilobezzia (A.) estepae and Stilobezzia (A.) succinea.