Stilobezzia (Acanthohelea) patagonica 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 : 29-32

Stilobezzia (Acanthohelea) patagonica Ingram and Macfie, 1931

( Figures 9, 18)

Stilobezzia patagonica Ingram and Macfie, 1931: 196 (female, male; Argentina).

Stilobezzia (Neostilobezzia) patagonica: Das Gupta and Wirth, 1968: 141 (in list) Wirth, 1974: 43 (in catalogue of New World species south of USA).

Stilobezzia (Acanthohelea) patagonica: Spinelli and Wirth, 1993: 51 (in list; Argentina); Borkent and Wirth, 1997: 109 (in World catalogue); Borkent and Spinelli, 2000: 53 (in catalogue of species of southern USA); Borkent and Spinelli, 2007: 85 (in Neotropical synopsis); Borkent, 2014: 135 (in online World catalogue).

Diagnosis

The only Patagonian species of Stilobezzia (Acanthohelea) in which males have the scutellum pale with 5–6 large setae and the postscutellum dark brown. Females with elongated, retort-shaped spermathecae, with proximal portion wide, ovoid and distal portion narrow.

Male. Head ( Figure 9A). Dark brown. Antennal flagellum brown, plume brown, poorly developed; antennal ratio 1.20–1.36 (1.27, n = 8). Palpus brown; segment 3 as long as 5; palpal ratio 2.60–3.80 (3.34, n = 11).

Thorax ( Figure 9C). Scutum dark brown, humeral pits pale, prescutellar depression paler in some specimens; scutellum pale with 5–6 large setae; postscutellum dark brown; pleura dark brown. Legs brown; tarsomere 1 of hind leg with two ventral rows of setae; hind tibial comb with 7 spines; prothoracic TR 1.61–1.71 (1.68, n = 13); mesothoracic TR 1.92–2.16 (2.03, n = 13); metathoracic 1.67–1.92 (1.75, n = 14). Wing ( Figure 9B) length 1.22–1.77 (1.64, n = 14) mm, width 0.45–0.64 (0.57, n = 14) mm, costal ratio 0.68–0.73 (0.70, n = 10); membrane slightly infuscated; second radial cell 1.90–2.62 (2.13, n = 10) × longer than first; cubital fork originating distal to level of base of r-m cross vein; macrotrichia on costa, R 1; abundant on distal margin of cell r 3, m 1, sparse on m 2. Halter whitish.

Abdomen. Brown. Genitalia ( Figure 9D): tergite 9 extending to apex of gonocoxites, narrowing progressively distad, posterior margin rounded; sternite 9 7.50× broader than long, posteromedian excavation deep, broad; sternite 10 wide, narrowing to base of cerci; cerci stout, subparallel. Gonocoxite 1.60× longer than greatest breadth; gonostylus 1.25× shorter than gonocoxite, nearly straight, blunt tip. Parameres subparallel; basal apodemes curved, stems slender proximally, swollen at mid portion posteromedian process rod like, tip spoon-shaped. Aedeagus 0.60× length of basal breadth, composed of two sinuous sclerites, each swollen at mid portion, tip pointed.

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

Head ( Figure 9E). Antennal ratio 1.00–1.20 (1.09, n = 17); palpal ratio 3.00–3.80 (3.48, n = 18). Mandible with 7 coarse teeth.

Thorax. Scutellum with 6–7 large setae; hind tibial comb with 8–9 spines; prothoracic TR 1.77–1.91 (1.84, n = 17), mesothoracic TR 2.15–2.36 (2.22, n = 17), metathoracic TR 1.80–2.09 (1.93, n = 17). Wing ( Figure 9F) length 1.65–2.24 (1.89, n = 18) mm, width 0.64–0.85 (0.73, n = 18) mm, costal ratio 0.70–0.75 (0.73, n = 8); second radial cell 2.10–3.40 (2.80, n = 18)× longer than first; cubital fork originating at same level of base of r-m cross vein; macrotrichia on costa, R 1, R 2, R 3, M 1, M 2, CuA 2, CuP, abundant on cell r 3, m 1, m 2, sparse on cua 1. Halter whitish.

Abdomen. Brown. Genitalia ( Figure 9G) anterior margin of sternite 8 convex, lateral margins subparallel; posteromedian excavation U-shaped; sternite 10 with 4 pairs of setae; two elongated, retort-shaped spermathecae, with proximal portion wide, ovoid, distal portion narrow, necks nearly imperceptible, measuring 14.40–20.40 (16.60, n = 18) by 5.10–7.00 (6.00, n = 18) µm and 11.40–17.5 (14.5, n = 18) by 3.30–5.50 (5.30, n = 18) µm; plus a small third rudimentary spermatheca.

Distribution

Argentina (Neuquen, Río Negro), Chile (Ñuble, Valdivia) ( Figure 18).

Types

Holotype male, allotype female, Argentina, Río Negro prov., Bariloche , 28 November to 1 December 1926, P. and M. Edwards ( BMNH).

Other specimens examined

Argentina: Neuquen prov., 10 km N San Martín de Los Andes, 24 November 1984, G. Spinelli, 1 female, sweep net; Villa La Angostura, 11/ 15 January 2004, G. Spinelli, 1 male, 1 female, light trap; Quila Quina, 17 November 1994, G. Spinelli, 3 males, 1 female, sweep net; arroyo Quechuquina , 16 November 1994, G. Spinelli, 1 male, sweep net; lago Lolog , 24 November 1984, J. A. Downes, 2 males, 1 female, sweep net (JAD 1651/3/11,12,15) ( CNCI); Cerro Chapelco, sobre lago Lacar, 27 November 1984, J. A. Downes, 3 males, sweep net (JAD 1653/1/?,17,20) ( CNCI) ; Río Negro prov., 6 km O extremo S lago Mascardi, 28 November 1984, G. Spinelli, 1 female, sweep net; lago Mascardi , 28 November 1984, J. A. Downes, 1 female, sweep net (JAD 1655/1/7) ( CNCI); lago Gutiérrez, January 2003, J. Liotta, 1 male, light trap; lago Steffen, 29/ 30 November 1999, P. Marino – G. Spinelli, 2 males, 1 female, sweep net .

Chile: Ñuble prov. , Alto Tregualemu, S E Chovellen, 500 m, 24 January 1979, D. Davis – M. Davis – B. Akerbergs, 2 females; Recinto 800 m, 22 January 1979, D. Davis – M. Davis – B. Akerbergs, 2 females; Valdivia prov ., Isla Teja , 1 December 1984, J. A. Downes, 1 female, sweep net (JAD 1657/1/10) ( CNCI) ; same data except 3 December 1984, 1 male, 1 female JAD 1658/1/11,12) ( CNCI) ; Isla Teja , campo de la Universidad, 12 December 1984, J. A. Downes, 2 females, 2 males, sweep net (JAD 1666/1/11,12,13,14) ( CNCI) ; same data except 13 December 1984, 2 males, 2 females, (JAD 1667/1/4,5,6,7) ( CNCI) .

Discussion

The females of Stilobezzia patagonica resemble S. megatheca by the elongated spermathecae, but S. megatheca has a flask-shaped spermathecae and the anterior margin of sternite 8 straight. Males are similar to S. estepae sp. n., but the latter species can be distinguished by the presence of a small, triangular sclerite located at proximal 1/3 of distal stem of parameres and the gonostylus stout with pointed tip.

In some of the examined males, the posteromedian processes of parameres look like articulated to mid portion of stem.