Stilobezzia (Acanthohelea) spinosa Cazorla and Spinelli, 2014

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 : 36-38

Stilobezzia (Acanthohelea) spinosa Cazorla and Spinelli sp. nov.

( Figures 11, 21)

Diagnosis

The only Patagonian species of Stilobezzia (Acanthohelea) in which males have three distal, elongated spines on hind tibia and first tarsomere of hind leg with a row of spines. Females spermathecae ovoid and hyaline with sclerotized, short necks.

Male. Head ( Figure 11A). Dark brown. Antennal flagellum brown; plume dark brown, poorly developed; antennal ratio 1.02–1.09 (1.05, n = 5). Palpus brown; segment 3 slightly longer than 5; palpal ratio 3.71–4.29 (3.20, n = 10).

Thorax. Scutum dark brown, humeral pits yellowish; scutellum yellowish with 11 large setae; postscutellum dark brown. Legs brown, with dense dark setae, hind leg stouter; hind tibia with three distal, elongated spines; tarsomere 1 of hind leg with row of spines ( Figure 11C); hind tibial comb with 7–8 spines; prothoracic TR 1.85–2.00 (1.95, n = 10); mesothoracic TR 1.85–2.00 (2.06, n = 9); metathoracic TR 2.16–2.40 (2.25, n = 10). Wing ( Figure 11B) length 1.70–1.94 (1.81, n = 10) mm, width 0.57– 0.67 (0.62, n = 10) mm, costal ratio 0.69–0.71 (0.70, n = 10); membrane slightly infuscated; second radial cell 2.62–3.50 (3.30, n = 10) × 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, sparse on cell r 3. Halter pale.

Abdomen. Brown, with dense setae. Genitalia ( Figures 11D, E) dark brown; tergite 9 extending 0.86× of gonocoxites length, posterior margin rounded; sternite 9 hyaline, spiculate, posterior margin convex; sternite 10 spiculate, produced beyond base of cerci; cerci slender, divergent. Gonocoxite very stout, 1.28× longer than greatest breadth, gonostylus slightly shorter than gonocoxite, curved, basal portion stout, narrowing to rounded tip. Parameres subparallel ( Figure 11E), apodemes slender; stem short, stout, broadening distally, tip ladle-shaped. A small triangular sclerite located at proximal 1/3 of stem of parameres. Aedeagus 0.8× length of basal breadth, composed of two sclerites with basal 2/3 very slender, curved, distal 1/3 swollen with mesally directed pointed tip.

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

Head ( Figure 11F) dark brown. Antennal flagellum dark brown; antennal ratio 1.19–1.41 (1.33, n = 7). Palpal ratio 3.00–3.33 (3.19, n = 7). Mandible with 7 coarse teeth.

Thorax ( Figure 11H). Scutellum with 11 stout, 8 thinner setae; hind tibial comb with 7 spines; claws stout, shorter than tarsomeres 5; hind tibial comb with 9–10 spines; prothoracic 2.00–2.20 (2.10, n = 7); mesothoracic TR 2.00–2.17 (2.10, n = 7); metathoracic TR 2.36–2.50 (2.49, n = 7). Wing ( Figure 11G) length 1.88–1.94 (1.91, n = 7) mm, width 0.73–0.76 (0.75, n = 7) mm, costal ratio 0.71–0.75 (0.74, n = 7), second radial cell 3.11–3.85 (3.52, n = 5) × longer than first; cubital fork originating slightly distal to level of base of r-m cross vein; macrotrichia on costa, R 1, R 2, R 3, M 1, M 2, Cua 1, abundant on cells r 3, m 1, sparse on cell cua 1.

Abdomen. Genitalia ( Figure 11I): anterior margin of sternite 8 slightly concave; posteromedian excavation V-shaped; sternite 10 with 6–7 pairs of setae; cerci conspicuous, rounded; two ovoid, hyaline spermathecae with sclerotized, short necks, measuring 7.40–8.50 (7.80, n = 7) by 5.50–7.40 (6.50, n = 7) µm and 5.90–8.50 (6.40, n = 7) by 4.40–5.90 (5.30, n = 7) µm; plus a third rudimentary spermatheca.

Distribution

Argentina (Río Negro) ( Figure 21).

Types

Holotype male, allotype female, Argentina, Río Negro, Parque Nacional Nahuel Huapi, Puerto Blest, mallin La Heladera , 41°00 ′ 56 ″ S, 71°49 ′ 45.4 ″ W, 878 m, 7 January to 4 February 2007, A. Garré – F. Montes de Oca – J. Massaferro, Malaise trap ( MLPA). Other paratypes: 9 males, 6 females, as follows: same data as holotype, 5 males; Argentina, 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, J. Massaferro – A. Garre – F. Montes de Oca , 2 females, 2 males Malaise trap; 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, 2 males, 4 females, Malaise trap.

Etymology

The name spinosa refers to the spinose first tarsomere of hind leg.

Discussion

This species strongly resembles S. (A.) succinea . The latter species can be distinguished by the general coloration yellowish brown, the apex of hind tibia darker, the inner margin of gonocoxite with a pointed tubercle and the sclerotized spermathecae.