Stilobezzia (Acanthohelea) succinea 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 : 38-41

Stilobezzia (Acanthohelea) succinea Ingram and Macfie, 1931

( Figures 12, 20)

Stilobezzia succinea Ingram and Macfie, 1931: 200 (female, male; Argentina)

Stilobezzia (Neostilobezzia) succinea: Das Gupta and Wirth, 1968:142 (in list); Wirth, 1974: 43 (in catalogue of New World species south of USA).

Stilobezzia (Acanthohelea) succinea: Spinelli and Wirth, 1993: 51 (in list; Argentina); Borkent and Wirth, 1997: 233 (in World catalogue); Spinelli and Grogan, 1999: 709 (in list; Tierra del Fuego); 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) in which both sexes have the scutum yellowish brown except humeral pits and mesal region anterior to prescutellar depression that are yellowish; legs are yellowish brown except the apex of hind tibia darker; males hind leg stouter, hind tibia with 2–3 apical stout spines and tergite 9 with a posterolateral membranous extension.

Male. Head ( Figure 12A). Dark brown. Antennal flagellum dark brown, plume dark brown, dense; antennal ratio 1.50–1.52 (1.51, n = 2). Palpus dark brown; segment 3 slightly longer than 5; palpal ratio 3.16–4.20 (3.87, n = 5).

Thorax ( Figure 12C). Scutum yellowish brown except humeral pits, mesal region anterior to prescutellar depression yellowish; scutellum yellowish with 7–14 large, 10 thinner setae; postscutellum dark brown; pleura dark brown, katepisternum slightly paler mesally. Legs yellowish brown, with dense setae; hind leg stouter; apex of hind tibia darker with 2–3 distal stout spines; mid leg with 2 apical spines; hind tibial comb with 8 spines; prothoracic TR 1.78–2.00 (1.91, n = 5), mesothoracic TR 1.87–2.20 (2.09, n = 5), metathoracic TR1.77–1.87 (1.83, n = 5). Wing ( Figure 12B) length 1.96– 2.70 (2.21, n = 5) mm, width 0.74–0.93 (0.78, n = 5) mm, costal ratio 0.70–0.73 (0.72, n = 5); membrane slightly infuscated; second radial cell 2.73–4.14 (3.50, n = 5) × longer than first; cubital fork originating distal 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. Yellowish brown, with dense setae. Genitalia ( Figure 12D): yellowish brown; tergite 9 extending 0.72 of gonocoxite length, posterior margin rounded with posterolateral membranous extension; sternite 9 6.60× broader than long, with narrow, shallow posteromedian excavation; sternite 10 narrow, produced beyond base of cerci; cerci slender, divergent. Gonocoxite stout, 1.34× longer than greatest breadth, inner margin with pointed tubercle, directed mesad; gonostylus slightly shorter than gonocoxite, nearly straight, tip blunt. Parameres subparallel, sclerotized; apodemes slender, rounded; stem rod like, with bulbous tip. A small triangular sclerite located at proximal 1/3 of stem of parameres. Aedeagus 0.66× length of basal breadth, composed of two slender, sinuous sclerites, each with apex pointed.

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

Head ( Figure 12E). Yellowish brown. Antennal flagellum dark brown; antennal ratio 1.34–1.50 (1.41, n = 5). Palpus dark brown; palpal ratio 3.43–4.50 (4.01, n = 6). Mandible with 7–8 coarse teeth.

Thorax. General coloration paler; scutellum with 9–11 large, 8–9 thinner setae; hind tibial comb with 7–9 spines; prothoracic TR 1.92–2.08 (2.00, n = 9), mesothoracic TR 2.10–2.23 (2.16, n = 9), metathoracic TR 1.78–2.00 (1.93, n = 9). Wing ( Figure 12F) length 1.91–2.66 (2.40, n = 9) mm, width 0.81–1.02 (0.92, n = 9), costal ratio 0.73–0.80 (0.76, n = 9); second radial cell 3.22–5.00 (3.80, n = 11) × longer than first; cubital fork originating at level of base of r-m cross vein; macrotrichia on costa, R 1, R 3,M 1, M 2, CuA 2, abundant on distal 1/4 of cells r 3, m 1, sparse on distal margin of cells m 2, cua 1. Halter whitish.

Abdomen. Yellowish brown, with dense setae. Genitalia ( Figure 12G): anterior margin of sternite 8 straight, sclerotized, lateral margins subparallel, posteromedian excavation V-shaped; sternite 10 with 5–6 pairs of setae; cerci rounded, elongated; two globose spermathecae with slender necks, only basal portion sclerotized, measuring 10.30–12.90 (11.30, n = 6) by 9.20–10.70 (9.80, n = 6) µm and 9.20–11.10 (10.00, n = 6) × 6.60–9.20 (8.10, n = 6) µm; plus a third rudimentary spermatheca.

Distribution

Argentina (Neuquen, Río Negro) ( Figure 20) .

Types

Holotype male, allotype female, 1 paratype male: Argentina, Río Negro prov., Bariloche , 22 November to 1 December 1926, F. and M. Edwards ( BMNH).

Other specimens examined

Argentina: Neuquen prov., Parque Nacional Nahuel Huapi, Puerto Blest, mallin La Heladera , 41°00 ′ 56 ″ S, 71°49 ′ 45.4 ″ W, 878 m, 15 December 2006 to 7 January 2007, A. Garré – F. Montes de Oca – J. Massaferro, 5 females, Malaise trap; same data except 2 males, 3 females, sweep net ; Río Negro prov., Parque Nacional Nahuel Huapi, arroyo Ñireco (Complejo Challhuaco) 41°11 ′ 51.9 ″ S, 71°19 ′ 40 ″ W, 962 m, 20 December 2006 to 23 January 2007, A. Garré – F. Montes de Oca , 1 male, 6 females, Malaise trap; same data except sweep net, 2 males, 1 female; Parque Nacional Nahuel Huapi, mallin de Los Patos, 41°15 ′ 48.6 ″ S, 71°17 ′ 50.3 ″ W, 1020 m, 20 December 2006 to 3 January 2007, A. Garré – F. Montes de Oca , 4 males, 6 females, Malaise trap; lago Cántaros 41°00 ′ 34 ″ S, 71°49 ′ 19.7 ″ W, 873 m, 11 January 2007, A. Garré – F. Montes de Oca , 1 male, sweep net; Parque Nacional Nahuel Huapi, laguna los Clavos, 41°04 ′ 48.6 ″ S, 71°49 ′ 33.9 ″ W, 1194 m, 5 February to 3 March 2007, A. Garré – F. Montes de Oca , 5 males, 7 females, Malaise trap .

Discussion

Stilobezzia (A.) succinea is somewhat similar to S. (A.) spinosa . Characters for distinguishing both species are in the key and in the discussion section of that species.