Austrohelea shannoni (Wirth & Blanton)

(Figs. 1 ̄12, 29̄30)

Monohelea (Isthmohelea) shannoni Wirth & Blanton, 1972: 175 (female; Argentina); Wirth 1974: 40 (in New World catalogue south of the USA).

Austrohelea shannoni: Wirth & Grogan 1988: 23 (combination; figs. female, male); Spinelli & Wirth 1993: 39 (in list of Ceratopogonidae of Argentina); Borkent & Wirth 1997: 91 (in World catalogue); Spinelli 1998: 325 (in list of Ceratopogonidae of Argentina); Borkent & Spinelli 2000: 44 (in New World catalogue south of the USA); Borkent & Spinelli 2007: 77 (in Neotropical catalogue); Spinelli & Marino 2009: 205 (in list of Ceratopogonidae of Patagonia); Borkent 2016: 115 (in online World catalogue).

Diagnosis. A large, dark brown Neotropical species. Males lacking a sensory pit on palpal segment 3; legs slender; posterior margin of tergite 9 slightly notched, with short, stout widely spaced apicolateral processes and triangular cerci; gonocoxite tapering distally with basomesal tubercle; gonostylus as long as gonocoxite; parameres with anterior arm of basal apodeme slender, posterior arm stout, longer, forming an acute angle between both arms; basal arch of aedeagus V-shaped. Females lacking a sensory pit on palpal segment 3, with slender legs and unequal, ovoid spermathecae with moderately long necks.

Male. Head (Fig. 1) dark brown. Eyes narrowly contiguous on extreme lower portions; with fine interommatidial spicules. Antennal flagellum (Fig. 2) with flagellomeres 2̄8 barrel-shaped, 9̄10 vasiform, 11̄13 elongate, 11 longest; plume well developed, moderately dense, extending to apex of flagellomere 12; flagellomere 12 with single subapical sensillum coeloconicum; antennal ratio 0.73̄0.75 (0.74, n = 4). Clypeus with 3̄5 pairs of setae. Palpus moderately long; segment 5 extending well beyond apex of proboscis; segment 3 elongate with a few capitate sensilla on distal 1/3 of mesal surface; palpal ratio 3.00̄3.39 (3.20, n = 5). Thorax dark brown. Legs similar to those of female except for the tarsal claws, which are shorter, equal, without basal inner teeth, apices bifid; hind tibial ratio 11.00̄11.70 (11.53, n = 5); hind tarsal ratio 1.73̄1.82 (1.79, n = 5). Wing (Fig. 3) membrane infuscated brown, darkest on proximal section from base to apex of costa, radius and beyond r-m crossvein, slightly lighter on distal sections of cells r3, m1 and m2; veins dark brown; wing length 1.66̄1.98 (1.79, n = 4) mm; width 0.54̄0.59 (0.56, n = 4) mm; costal ratio 0.62̄0.64 (0.63, n = 4). Abdomen brown. Genitalia (Figs. 4, 29 ̄30). Tergite 9 tapering distally, posterior margin with shallow median notch; apicolateral processes short, stout widely spaced with a single small apical seta; cercus slender, triangular, folded ventrally; sternite 9 moderately long, twice as broad as long with shallow, concave posteromedian excavation. Gonocoxite stout, tapering distally, with mesobasal tubercle, surface with sparse coarse elongate setae; gonostylus as long as gonocoxite, nearly straight, distal half broad, tip pointed. Parameres (Fig. 29) separate, moderately sclerotized, somewhat boomerang-shaped; basal apodemes with slender anterior arm, posterior arm much longer, broader, apex truncate; an acute angle formed between anterior and posterior arms; distal portions elongate, slightly curved, apices divergent, slightly pointed. Aedeagus (Fig. 30) Y-shaped, slightly broader than long; basal arch V-shaped, extending 1/3 of total aedeagal length; basal arms heavily sclerotized, recurved 120˚, apices truncate; main body triangular, heavily sclerotized, tapering abruptly, apex sharply pointed, with a moderately long, lightly sclerotized distal process with short, slender ventrally recurved tip.

Female. Head (Fig. 5) dark brown. Eyes barely contiguous, with fine interommatidial spicules. Antennal pedicel very dark brown, flagellum dark brown; flagellomeres 2̄8 short, slightly vasiform, 9̄13 elongate cylindrical, 13 longest; flagellomeres 8, 12 with single subapical sensillum coeloconicum; antennal ratio 1.23̄1.42 (1.32, n = 5). Clypeus with 3̄5 pairs of setae. Palpus brown; segment 3 slightly swollen, with a few capitate sensilla on distal 1/3 of mesal surface; palpal ratio 2.53̄3.12 (2.89, n = 5). Mandible with 8 large teeth (n =7). Thorax (Figs. 6 ̄7). Scutum, post-scutellum dark brown, humeral areas and scutellum slightly paler (more evident in specimens cleared with KOH); scutellum with 6̄7 large, 10̄12 smaller setae. Legs dark brown; fore, mid femora, tibiae slender; hind femur, tibia more massive with more numerous, long stout setae, especially on tibia; hind tibial ratio 8.10̄9.05 (8.57, n = 6); hind tibial comb with 5 spines; tarsi (Figs. 8-10) dark brown, tarsomeres 1̄2 slightly paler in some specimens; tarsomeres 1 with basal, apical ventral spines and 1̄5 similar spines along ventral surface on fore, mid legs; tarsomeres 2̄3 of fore, mid legs with apical spine; hind tarsomeres 1̄2 with two rows of ventral palisade setae; hind tarsal ratio 1.85̄1.95 (1.90, n = 6); tarsomere 4 of fore, mid legs short, cordiform, tarsomere 4 of hind leg elongate, cylindrical; claws small, equal-size on fore, mid legs, hind leg with single long claw, slightly longer than tarsomere 5 with a stout basal tooth about 1/3 length of claw. Wing (Fig. 11) membrane infuscated, darkest on distal 1/3, along veins and around radial cells; two well developed radial cells, 2nd broader, twice as long as 1st; macrotrichia most numerous on distal ½ of cell r3, less numerous in m1, m2, cua1 except near margin, sparse in anal cell; wing length 1.57̄1.85 (1.71, n = 6) mm, width 0.63̄0.75 (0.68, n = 6) mm; costal ratio 0.65̄0.67 (0.66, n = 7). Halter pale. Abdomen dark brown (Fig. 12). Sternite 9 with V-shaped posteromedian excavation; sternite 8 divided mesally, each half tapered; sternite 10 with two pairs of setae. Two ovoid, subequal spermathecae with moderately long, slender necks, measuring 60̄75 (65, n = 4) µm by 37̄42 (40, n = 4) µm, and 50̄68 (57, n = 4) µm by 33̄39 (37, n = 4) µm; a rudimentary third spermatheca present.

Material examined. ARGENTINA, Río Negro, 6 km oeste, extremo sur lago Mascardi, 28-XI- 1984, G. Spinelli, 1 female (MLPA) ; lago Escondido ( Llao-Llao), 29-XI-1984, G. Spinelli, 1 female (MLPA) . Tierra del Fuego, camino a Lapataia (turbera), 1-III-1993, G. Spinelli, 2 females (MLPA) ; 1 km norte río Tristen, 170 m, 2- III-1993, G. Spinelli, 1 female (MLPA) ; Estancia La Vega, 3-III-1993, G. Spinelli, 1 male (MLPA) . CHILE, Magallanes, Isla Wollaston, Bahia Scourfield, 17/ 25-II-1980, D. Lanfranco, Malaise trap, 4 males, 1 female (MLPA) .

Distribution. This species is known from Nothofagus forests of Río Negro and Tierra del Fuego provinces, Argentina, and on Wollaston Island, Chile (Fig. 35).

Discussion. This species was originally described by Wirth & Blanton (1972) on the basis of a single female from Bariloche, Río Negro province in northwestern Argentine Patagonia. In their book on the predaceous midges of the World, Wirth & Grogan (1988) provided a generic diagnosis, the first description and data on males as well as illustrations of both sexes based on specimens from Wollaston Island, which is located at the extreme southeastern-most tip of Chile south of the Beagle channel. We examined specimens from Bariloche and the Island of Tierra del Fuego, Argentina, and also from Wollaston Island, Chile, and therefore, we confirm the validity of the sex association assumed by Wirth & Grogan (1988). Austrohelea shannoni is most similar to A. spinosa n. sp. Characters to distinguish both species are in the key and the discussion section of the latter species.