Stilobezzia (Acanthohelea) tridentis , Cazorla and Spinelli 2014, sp. nov.
Creators: name: Cazorla, Carla G.
name: Spinelli, Gustavo R.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Ceratopogonidae
Stilobezzia
Stilobezzia tridentis

description: Stilobezzia (Acanthohelea) tridentis, Cazorla and Spinelli sp. nov.
(Figures 13, 19)
Diagnosis
The only Patagonian species of Stilobezzia (Acanthohelea) in which males have aedeagal sclerites with a short distolateral process and distal portion curved with a basal tooth and tip pointed. Females sternite 8 large and globose, and spermathecae sclerotized with hyaline punctuations.
Male. Head (Figure 13A). Dark brown. Antennal flagellum dark brown; plume dark brown, well developed; antennal ratio 1.12–1.22 (1.18, n = 3). Palpus dark brown; segment 3 slightly shorter than 5; palpal ratio 2.66–3.60 (3.14, n = 5).
Thorax (Figure 13B). Scutum dark brown; scutellum pale brown with 7–8 large setae; postscutellum dark brown. Legs stout, dark brown, hind leg darker; hind tibial comb with 9 spines; prothoracic TR 1.70–1.90 (1.83, n = 5); mesothoracic TR 2.09– 2.36 (2.20, n = 5); metathoracic TR 2.00–2.28 (2.14, n = 5). Wing (Figure 13C) length 1.45–1.92 (1.78, n = 5) mm, width 0.52–0.69 (0.64, n = 5) mm, costal ratio 0.70–0.75 (0.73, n = 6); membrane slightly infuscated; second radial cell 2.18–2.88 (2.56, n = 6) × longer than first; cubital fork originating distal to base of r-m cross vein; macrotrichia on costa, R 1, R 2, R 3, M 1, M 2, sparse on cells r 3, m 1. Halter whitish.
Abdomen. Dark brown. Genitalia (Figures 13D, E): tergite 9 extending 0.91 of gonocoxite length, narrowing distad, posterior margin rounded with small pointed projection; sternite 9 3.90× broader than long; sternite 10, narrowing distad, extending slightly beyond apex of cerci; cerci slender, divergent. Gonocoxite stout, two times longer than greatest breadth, inner margin with anteromesal blunt tubercle, gonostylus 1.33× shorter than gonocoxite, slightly curved, basal 1/4 wide, narrowing to pointed tip. Parameres slightly sclerotized, subparallel; stem stout, rounded tip. Aedeagus 1.20× longer than basal breadth; composed of two heavily sclerotized sclerites, each with anterior portion stout, straight, with short distolateral process; distal portion curved with basal tooth, tip pointed.
Female. Head (Figure 13F). Antennal ratio 1.34–1.69 (1.55, n = 8); palpal ratio 3.00– 3.10 (3.05, n = 8). Mandible with 7 coarse teeth.
Thorax. Scutum dark brown, humeral pits pale brown; scutellum pale brown with 7–8 large, 2 thinner setae; prothoracic TR 1.75–2.00 (1.87, n = 8); mesothoracic TR 2.08–2.36 (2.21, n = 8); metathoracic TR. 1.91–2.25 (2.12, n = 8). Wing (Figure 13G) length 1.76–1.86 (1.82, n = 8) mm, width 0.70–0.76 (0.73, n = 8) mm, costal ratio 0.71–0.77 (0.75, n = 10); membrane slightly infuscated; second radial cell 2.70–3.57 (3.06, n = 7) × 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, M 2 y CuA 2, abundant on distal half of cells r 3, m 1, sparse on cells m 2, cua 1.
Abdomen. Dark brown, segments 7–8 slightly darker. Genitalia (Figure 13H): sternite 8 large, anterior margin convex, lateral margins subparallel, posteromedian excavation deep, V-shaped; sternite 10 with 4–5 pairs of setae, cerci short, rounded; two globose, heavily sclerotized spermathecae with hyaline punctuations with nearly imperceptible necks, measuring 7.40–9.20 (8.40, n = 5) by 5.50–7.70 (6.40, n = 5) µm and 4.80–7.40 (6.20, n = 5) by 3.70–5.70 (4.70, n = 5) µm; plus a third rudimentary spermatheca.
Distribution
Argentina (Neuquen, Río Negro); Chile (Malleco, Chiloé) (Figure 19).
Types
Holotype male, allotype female, Chile, Malleco prov., Cordillera de Las Raíces, 40 km E de Curacautín, 1650 m, 5 February 979, D. and M. Davies – B. Akerbergs (MLPA). Other paratypes: 7 males, 14 females, as follows: Argentina, Neuquen prov., Parque Nacional Nahuel Huapi, lago Espejo, 40°38 ′ 49.3 ″ S, 71°42 ′ 12.7 ″ W, 903 m, 23 February to 5 March 2008, A. Garré – F. Montes de Oca, 2 males, 2 females, Malaise trap; Río Negro prov., Parque Nacional Nahuel Huapi, río Manso superior, 41°14 ′ 8.1 ″ S, 71°46 ′ 58.5 ″ W, 845 m, 7 February to 2 March 2007, A. Garré – F. Montes de Oca, 7 females (one in BMNH, one in USNM), 2 males (one in BMNH, one in USNM), Malaise trap; same data except 41°14 ′ 28.4 ″ S, 71°44 ′ 12.6 ″ W, 837 m, 1 female, 2 males; same data except La Cantera, 41°21 ′ 16 ″ S, 71°42 ′ 27.3 ″ W, 764 m, 15 January to 7 February 2007, A. Garré – F. Montes de Oca, 2 males, Malaise trap; Parque Nacional Nahuel Huapi, laguna Mercedes, 40°52 ′ 43.4 ″ S, 71° 34 ′ 41 ″ W, 899 m, 3–21 January 2008, A. Garré – F. Montes de Oca, 1 female, Malaise trap; Chile, Chiloé prov., Huillinco, 4 December 1984, J. A. Downes, 3 females, sweep net (JAD 1722/1/22; 1690/4/43; 1691/2/58) (CNCI).
Etymology
The name tridentis refers the particular shape of the aedeagal sclerites.
Discussion
This species is similar to S. (A.) nigerrima. However, S. nigerrima differs by the thorax uniformly dark brown, the sternite 8 of females with V-shaped posteromedian excavation and the slender aedeagal sclerites, which are nearly straight with recurved basal arms and truncate tip.
description: Published as part of 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), pp. 155-209 in Journal of Natural History 49 (3) on pages 195-198, DOI: 10.1080/00222933.2014.939728, http://zenodo.org/record/4002623