Stilobezzia (Acanthohelea) megatheca 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 megatheca

description: Stilobezzia (Acanthohelea) megatheca Cazorla and Spinelli sp. nov.
(Figures 5, 17)
Diagnosis
The only Patagonian species of Stilobezzia (Acanthohelea) in which males have the posterior margin of tergite 9 with a small, rounded, hyaline projection. Females have two large, greatly elongated flask-shaped spermathecae and sternite 8 with a Ushaped posteromedian excavation.
Male. Head (Figure 5A). Dark brown. Antennal flagellum dark brown; plume dark brown, poorly developed; antennal ratio 1.50–1.91 (1.69, n = 13). Palpus brown; segment 3 as long as 5; palpal ratio 3.16–3.80 (3.41, n = 24).
Thorax (Figure 5C). Scutum dark brown, humeral pits pale yellowish; scutellum pale yellowish with 6 large setae; postscutellum dark brown. Legs uniformly brown; hind tibial comb with 7 spines; prothoracic TR 1.73–1.92 (1.84, n = 25); mesothoracic TR 2.00–2.33 (2.13, n = 23); metathoracic TR 1.79–1.92 (1.87, n = 26). Wing (Figure 5B) length 1.64–2.03 (1.70, n = 26) mm, width 0.58–0.67 (0.62, n = 26) mm, costal ratio 0.68– 0.74 (0.72, n = 10); membrane slightly infuscated; second radial cell 2.78–3.83 (3.11, n = 13) × longer than first; cubital fork originating slightly distal to base of r-m cross vein; macrotrichia on costa, R 1, R 3, M 1, M 2, wing margin, sparse on cells r 3, m 1. Halter pale.
Abdomen. Dark brown. Genitalia (Figure 5D): tergite 9 extending 0.92 of gonocoxite length, posterior margin rounded with small, hyaline, rounded projection; sternite 9 4.3× broader than long, with broad, deep, posteromedian excavation; sternite 10 narrow, spiculate, extending to base of cerci; cerci slender, divergent. Gonocoxite 1.27× longer than greatest breadth, inner margin with anteromesal pointed tubercle; gonostylus slightly shorter than gonocoxite, stout, nearly straight, with dorsal subapical bulk; tip heavily sclerotized, beak-like, sharply pointed, tip pointed, heavily sclerotized, directed anteriorly. Parameres contiguous anteriorly, slightly divergent distally, basal apodemes slightly curved; each with stem rod-shaped, tip bulbous. A small triangular sclerite located just anterior to base of parameres. Aedeagus 0.66× length of basal breadth, composed of two slender, sinuous sclerites, each with proximal portion curved laterad, tips pointed, separated.
Female. Smaller, similar to male, with the following notable differences:
Head (Figure 5E). Dark brown. Antennal flagellum brown; antennal ratio 1.33– 1.51 (1.39, n = 8); palpal ratio 2.75–3.95 (2.96, n = 10). Mandible with 7 coarse teeth.
Thorax. Scutellum with 5 large, 3 thinner setae. Legs prothoracic TR 1.73–1.90 (1.81, n = 9); mesothoracic TR 2.08–2.30 (2.16, n = 9); metathoracic TR 2.00–2.30 (2.17, n = 8). Wing (Figure 5F) length 1.34–1.68 (1.51, n = 10) mm, width 0.60 (0.55– 0.66, n = 10) mm; costal ratio 0.66–0.73 (0.70, n = 9); membrane slightly infuscated; second radial cell 2.12–2.85 (2.5, n = 10) × longer than first; macrotrichia on costa, R 1, R 2, M 1, M 2, CuA 2, abundant on distal 1/3 of cells r 3, m 1, sparse on cell m 2.
Abdomen (Figure 5G). Anterior margin of sternite 8 straight, lateral margins subparallel; posteromedian excavation U-shaped, shallow; sternite 10 with 4–5 pairs of setae; cerci rounded. Two large, greatly elongated, flask-shaped spermathecae with short necks, measuring 22.30–26.10 (24.40, n = 10) by 3.70–9.20 (7.20, n = 10) µm and 18.90–23.70 (21.90, n = 10) by 5.50–7.70 (6.60, n = 10) µm; plus a third small, ovoid spermathecae measuring 3.60–6.20 (4.80, n = 10) µm.
Distribution
Argentina (Neuquen, Río Negro, Chubut), Chile (Valdivia, Osorno, Llanquihue, Chiloé) (Figure 17)
Types
Holotype male, allotype female, Argentina, Neuquen prov., Villa La Angostura, 11– 15 January 2004, G. Spinelli, light trap (MLPA). Other paratypes: 39 males, 24 females, as follows: Argentina, Neuquen prov., lago Aluminé, 22 December 1996 to 3 January 1997, 1 male, D. Podestá, Malaise trap; cerro Chapelco, sobre lago Lacar, 27 November 1984, J. A. Downes, 5 males, sweep net (JAD 1653/1/6,18, 20; 1653/2/ 17,19) (CNCI); lago Lolog, 24 November 1984, J. A. Downes, 2 males, sweep net (JAD 1651/3/13,14,28) (CNCI); Río Negro prov., El Bolsón, 29 December 1999, G. Spinelli, 1 male, light trap; río Villegas, 57 km S Bariloche, 8–3 December 1994, L. Quate, 1 male, Malaise trap; lago Gutiérrez, January 2003, J. Liotta, 9 males, light trap; lago Gutiérrez, 20 January 2006, Grogan and Spinelli, 1 male, sweep net; arroyo Los Notros, 20 km O Bariloche, 26–28 November 1994, L. Quate, 4 males, Malaise trap; Parque Nacional Nahuel Huapi, arroyo Ñireco (Complejo Challhuaco) 41°11 ′ 51.9 ″ S, 71°19 ′ 40.5 ″ W, 962 m, 23 January to 18 February 2007, Garré and Montes de Oca, 1 male, Malaise trap; Chubut prov., Parque Nacional Los Alerces, margen E lago Futalaufquen, 20 January 1988, G. Spinelli, 2 males, 1 female, sweep net; Parque Nacional Los Alerces, 9–12 December 1994, L. Quate, 5 males, Malaise trap; Parque Nacional Los Alerces, arroyo s/n 2 February 2005, M. Donato, 1 male, sweep net.
Chile, Valdivia prov., Fundo San Martín, 15 November 1984, J. A. Downes, sweep net, 2 females (JAD 1669/1/5; 1670/3/6) (CNCI); Osorno prov., Pucatrihue, 30 December 1992, G. Spinelli, 1 male, 1 female, sweep net (USNM); same data except 1 December 1992, 1 female; Llanquihue prov., Yerbas Buenas, 13 km N Ensenada, 1–6 December 1994, L. Quate, 2 males, light trap; 3 km N Ensenada, 1–2 December 1994, L. Quate, 1 male, 5 females, Malaise trap; same data except 4 December 1994, 1 female; road to Los Ulmos, 29 December 1984, J. A. Downes, 5 females, sweep net (JAD 1685/2/12,13,14,37,38) (CNCI); Ensenada, 11 December 1984, J. A. Downes, 2 males, sweep net (JAD 1695/1/4; 1695/5/2) (CNCI); Chiloé prov., Ancud, 1 January 1985, J. A. Downes, 1 female, sweep net (JAD 1688/3/15) (CNCI); Huillinco, 2 January 1985, J. A. Downes, 3 females, sweep net (JAD 1689/2/3,4,5) (CNCI); same data except 3 January 1985, J. A. Downes, 1 female, (JAD 1690/4/48) (CNCI); same data except 4 January 1985, 3 females, (JAD 1691/2/44) (CNCI).
Etymology
The name megatheca refers to the unique, conspicuous, greatly elongated flaskshaped spermathecae.
Discussion
This species is somewhat similar to S. (A.) estepae. Characters for distinguishing both species are in the discussion section of that species.
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 172-175, DOI: 10.1080/00222933.2014.939728, http://zenodo.org/record/4002623