Stilobezzia (Acanthohelea) varia Ingram and Macfie, 1931

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, pp. 1-55 : 44-54

Stilobezzia (Acanthohelea) varia Ingram and Macfie, 1931

( Figures 14, 22)

Stilobezzia varia Ingram and Macfie, 1931: 191 (male, female; Chile)

Stilobezzia (Neostilobezzia) varia: Das Gupta and Wirth, 1968: 143 (in list); Wirth, 1974: 44 (in catalogue of New World species south of USA).

Stilobezzia (Acanthohelea) varia: Spinelli and Wirth, 1993: 51 (in list; Argentina); Borkent and Wirth, 1997: 109 (in World catalogue); Spinelli and Grogan, 1999: 709 (distribution); Borkent and Spinelli, 2000: 53 (in catalogue of species of southern USA); Borkent and Spinelli, 2007: 86 (in Neotropical synopsis); Borkent, 2014: 136 (in online World catalogue).

Diagnosis

The only Patagonian species of Stilobezzia (Acanthohelea) with size and coloration highly variable; pleura is dark brown and legs are yellowish brown to dark brown, with dark, stout hairs; tarsomere 1 of hind leg with stout basal spine. Males gonostylus as long as gonocoxite, nearly straight but curving to pointed tip and parameres with stem rod-shaped, slightly divergent distally, with bulbous tip. Females sternite 8 with anterior margin straight, lateral margins subparallel and posteromedian excavation V-shaped.

Male. Head ( Figure 14). Dark brown. Antennal flagellum dark brown, plume dark brown, dense; antennal ratio 1.47–1.70 (1.62, n = 15). Palpus brown, segment 3 as long as 5; palpal ratio 3.57–4.40 (3.87, n = 18).

Thorax. Scutum dark brown to black, except humeral pits, two lateral bands and prescutellar depression yellowish brown; scutellum yellowish brown with 12–18 large, 6–10 thinner setae; postscutellum dark brown. Pleura dark brown, katepisternum partially paler. Legs yellowish brown to dark brown, with dense setae; coxae brown, hind coxa darker, distal half of hind femur darker; tarsomere 1 of mid leg, hind leg with basal stout spine; hind tibial comb with 10 spines; prothoracic TR 1.61–1.81 (1.71, n = 16), mesothoracic TR 1.74–2.00 (1.89, n = 16), metathoracic TR1.63–1.86 (1.73, n = 16). Wing ( Figure 14B) length 2.28–2.84 (1.55, n = 19) mm, width 0.74– 0.89 (0.82, n = 19) mm, costal ratio 0.68–0.77 (0.73, n = 10); membrane infuscated; second radial cell 3.00–5.33 (4.28, n = 16) × longer than first; cubital fork originating slightly distad to 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 cell m 1. Halter pale.

Abdomen. Dark brown. Genitalia ( Figures 14C, D): tergite 9 extending 0.80 of gonocoxites length, posterior margin rounded; sternite 9 8.45× broader than long, with posteromedian excavation broad, shallow; sternite 10 wide, stout, produced beyond base of cerci; cerci elongated, divergent. Gonocoxite stout, 1.3× longer than greatest breadth, inner margin with short, mesal tubercle directed mesad; gonostylus as long as gonocoxite, nearly straight, curving to pointed tip. Parameres subparallel ( Figure 14D), basal apodemes sclerotized; stem rod-shaped, slightly divergent distally, bulbous tip. Aedeagus 0.76 length of basal breadth, composed of two sinuous sclerites, each with mesal 1/3 broad, narrowing to apex.

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

Head ( Figure 14E). Antennal ratio1.50–1.87 (1.57, n = 18); palpal ratio 2.86–3.86 (3.41, n = 18). Mandible with 7 coarse teeth.

Thorax. Scutellum with 10–14 large, 6–10 thinner setae. Hind tibial comb with 8–9 spines; prothoracic TR 1.64–1.93 (1.78, n = 19), mesothoracic TR 1.88–2.19, (2.02, n = 19), metathoracic TR 1.70–2.00 (1.88, n = 20). Wing ( Figure 14F) length 2.05–2.66 (2.45, n = 22) mm, width 0.79–0.91 (0.93, n = 22) mm, costal ratio 0.69–0.80 (0.76, n = 10); second radial cell 2.64–5.71 (3.97, n = 22) X longer than first; cubital fork originating at level of base of r-m; macrotrichia on costa, R 1, R 3, M 1, M 2 y CuA 2, abundant on distal 1/4 of cell r 3 and apex of cell m 1, sparse on cell m 2. Halter pale.

Abdomen. Yellowish brown to dark brown, with dense setae. Genitalia ( Figure 14G): anterior margin of sternite 8 straight, lateral margins subparallel; posteromedian excavation V-shaped; sternite 10 with 5 pairs of setae; cerci short; two ovoid spermathecae with short necks, measuring 8.10–14.40 (10.20, n = 21) by 5.90–10.30 (8.30, n = 21) µm and 7.0–11.40 (8.40, n = 21) by 5.90–10.00 (7.50, n = 21) µm; plus a third rudimentary spermatheca.

Distribution

Argentina (Neuquen, Río Negro, Chubut, Santa Cruz, Tierra del Fuego) ; Chile (Malleco, Cautin, Valdivia, Osorno, Llanquihue, Chiloé, Magallanes) ( Figure 22) .

Types

Holotype male, Chile, Chiloé prov. , Ancud , 17–19 December 1926, P. and M. Edwards; Other paratypes: same data as holotype, 1 male, 1 female; Llanquihue prov., Puerto Varas, 16 December 1926, P. and M. Edwards, 1 female; Río Negro prov., Bariloche, 1 December 1926, P. and M. Edwards, 1 female ( BMNH).

Other specimens examined

Argentina, Neuquen prov., Parque Nacional Lanín, arroyo Quechuquina and lago Lacar, 18 January 2006, W. Grogan – G. Spinelli, 1 male, sweep net; lago Paimún, 10 February 1989, G. Spinelli, 2 males, 1 female, sweep net; lago Queñi, 28 January 1988, G. Spinelli, 1 male, sweep net; same data except 6–8 February 1999, P. Marino, 1 female, Malaise trap; lago Huechulafquen, 2 March 1998, G. Spinelli, 2 females, CDC light trap; lago Tromen, 7 February 1986, G. Spinelli, 1 female, sweep net; San Martín de los Andes, 23 April 1982, M. Gentile, 1 female, light trap; Villa La Angostura, 11–15 January 2004, G. Spinelli, 3 males, light trap; Río Negro prov., río Manso, 1 February 1986, G. Spinelli, 2 females, sweep net; Parque Nacional Nahuel Huapi, río Guillelmo, 20 January 2006 W. Grogan – G. Spinelli, 1 male, sweep net; Parque Nacional Nahuel Huapi, Puerto Blest, 9 December 1992, G. Spinelli, 1 male, sweep net; same data except 41°01 ′ 34.4 ″ S, 71°48 ′ 55.7 ″ W, 791 m, 13–16 December 2007, A. Garre – F. Montes de Oca, 1 male, at light; arroyo Challhuaco, 26 January 1988, G. Spinelli, 1 female, sweep net; lago Gutiérrez, January 2003, J. Liotta, 1 female, 1 male, light trap; Parque Nacional Nahuel Huapi, cerro Tronador, 25 January 1988, G. Spinelli, 2 males, sweep net; Parque Nacional Nahuel Huapi, río Manso Superior, 41°14 ′ 28.4 ″ S, 71°44 ′ 12.6 ″ W, 837 m, 15 January 2007, A. Garré – F. Montes de Oca, 13 females, sweep net; Parque Nacional Nahuel Huapi, arroyo Llum 41°16 ′ 13.3 ″ S, 71°30 ′ 56.7 ″ W, 857 m, 18 December 2006 to 4 January 2007, A. Garré – F. Montes de Oca, 1 male, 1 female, Malaise trap; Parque Nacional Nahuel Huapi, mallin La Cortadera, 41°05 ′ 13 ″ S, 71°48 ′ 26 ″ W, 769 m, 8 January to 3 February 2007, A. Garre – F. Montes de Oca, 1 male, 2 females, Malaise trap; Parque Nacional Nahuel Huapi, Manso Medio, 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, 1 female, Malaise trap; Parque Nacional Nahuel Huapi, arroyo Grande, 41°02 ′ 21.6 ″ S, 71° 48 ′ 27 ″ W, 763 m, 4–25 February 2007, A. Garre – F. Montes de Oca, 1 female, Malaise trap; Parque Nacional Nahuel Huapi, arroyo Ñireco (Complejo Challhuaco) 41°11 ′ 51.9 ″ S, 71°19 ′ 40.5 ″ W, 962 m, 20 December 2006 to 23 January 2007, Garré – Montes de Oca, 3 males, 5 females, Malaise trap; Parque Nacional Nahuel Huapi, mallin La Heladera, 41°00 ′ 6.4 ″ S, 71°49 ′ 40.3 ″ W, 878 m, 7 January to 4 February 2007, A. Garré – F. Montes de Oca, 1 male, 1 female Malaise trap (USNM); Chubut prov., Parque Nacional Los Alerces, margen E lago Futalaufquen, 20 January 1988, G. Spinelli, 2 males, 1 female, sweep net; same data except El Alerzal, 20 January 1988, G. Spinelli, 1 male; cerro Galera, 2–4 December 2002, G. Spinelli, 1 male, Malaise trap; Santa Cruz prov., Los Glaciares, lago Roca, 10 January 1988, G. Spinelli, 1 female, 1 male, sweep net; lago del Desierto, 11 December 1996, 1 female, 4 males, sweep net; lago San Martín, estancia La Maipú, laguna Talca, 8 December 2002, G. Spinelli, 1 male, sweep net; Tierra del Fuego prov., Parque Nacional Tierra del Fuego, 7–9 December 2005, G. Spinelli, 19 males, 12 females, Malaise trap; 6 December 2005, G. Spinelli, 1 female, sweep net; camino a Lapataia, 1 March 1993, G. Spinelli, 1 female, sweep net.

Chile: Malleco prov. , Termas de río Blanco, 1080 m, 22 January 1964, M. Irwin – L. Stange, 1 female, 1 male, sweep net; Cordillera de Las Raíces , 40 km E Curacautín, 1450 m, 5 February 1979, D. Davis – M. Davis – B. Akerbergs, 1 female, sweep net; Parque Nacional Conguillo , 21 December 1984, J. A. Downes, 1 male, 1 female (JAD1658/1/7,8) ( CNCI) ; same data except 22 December 1984, 1 male, 1 female; Cautin prov ., 12 km N Loncoche , 280 m., 10 November 1966, E. Schlinger, sweep net; Valdivia prov ., Isla Teja , 3 December 1984, J. A. Downes, 1 male, 1 female, sweep net (JAD1658/1/7,8) ( CNCI) ; same data except 1 December 1984, 2 males, 2 females (JAD 1657/1/6,7,9,12) ( CNCI) ; same data except University farm, 12 December 1984, 3 males, 2 females (JAD 1666/1/1,2,3,4,5) ( CNCI) ; same data except 13 December 1984, 1 female (JAD 1667/1/1) ( CNCI) ; Osorno prov. , Pucatrihue , Puente Hermoso , 29 January 1978, P. J. Spangler, 1 female, sweep net; Llanquihue prov., Fundo San Martín, 15 December 1984, J. A. Downes, 1 male, sweep net (JAD 1669/2/4) ( CNCI) ; Chiloé prov. , Ancud, 1 January 1985, J. A. Downes, 1 female, sweep net (JAD 1688/3/12) ( CNCI) ; Huillinco , 2 January 1985, J. A. Downes, 1 male, sweep net (JAD 1689/2/2) ( CNCI) ; Magallanes prov. , Bahia Scourfield, 17–25 February 1980, D. Lanfranco, 2 males, 3 females, Malaise trap .

Discussion

The variability observed between specimens of Stilobezzia (A.) varia from different localities with respect to coloration, size and pilosity is notorious and unique among the species of the subgenus Acanthohelea .

This species is very similar to S. pabloi . Characters for distinguishing both species are in the key and in the discussion section of that species.