Austrohelea sirii, Ronderos & Spinelli & Grogan, 2017

Ronderos, Maria M., Spinelli, Gustavo R. & Grogan, Willliam L., 2017, The Neotropical species of the predaceous midge genus Austrohelea Wirth & Grogan (Diptera: Ceratopogonidae), Zootaxa 4276 (2), pp. 255-269 : 260-263

Austrohelea sirii New Species

( Figs. 13 ̄19, 31̄32)

Diagnosis. A small (male wing length 1.06 mm, female wing length 1.16 mm), brown species. Both sexes with sensory pit on third palpal segment and slender legs. Males with posterior margin of tergite 9 deeply concave with elongate, cylindrical, slightly divergent apicolateral processes; gonocoxite short, stout, without basomesal tubercle; gonostylus longer than gonocoxite; parameres with moderately slender basal apodeme with an elongate, curved anterior arm; aedeagus triangular with slender, slightly curved basal arms, very low basal arch, and lightly sclerotized distal portion with rounded apex. Females with wing darkly infuscated with dense, coarse macrotrichia in all cells beyond r-m crossvein; and unequal size, pyriform spermathecae with short, broad, truncate necks.

Holotype male. Head ( Fig. 13 ) brown. Eyes narrowly contiguous with sparse interommatidial spicules. Antennal pedicel dark brown; flagellomeres 2̄8 globular, 9̄10 vasiform, 11̄13 elongate, 11 longest; plume sparse, well developed, extending beyond flagellomere 11; flagellomere 12 with single subapical sensillum coeloconicum; antennal ratio 0.81. Clypeus with 3 pairs of setae. Palpus moderately long, segments 4̄5 extending beyond proboscis; segment 3 moderately broad with small apicomesal pit; palpal ratio 2.33. Thorax brown except for pale scutellum; scutellum with 6 large, 8 smaller setae. Legs similar to those of female except for tarsal claws, which are shorter, equal size, without basal inner teeth, apices bifid; hind tibial ratio 9.00; hind tarsal ratio 1.68. Wing ( Fig. 14 ) membrane slightly infuscated, surface with dense macrotrichia along distal margin of cell r3, sparse above and below distal portion of vein M1 and apex of cell m1; veins brown, base of M2 thin, joined to M1; radial cells well developed, 2nd broader, nearly twice as long as 1st; wing length 1.06 mm, width 0.38 mm; costal ratio 0.57. Halter pale. Genitalia ( Figs. 15 , 31 ̄32). Tergite 9 tapering gradually distally, posterior margin narrow, deeply concave, apicolateral processes elongate, cylindrical, slightly divergent with a single apical seta; cercus slender; sternite 9 3.5 x broader than long with narrow, moderately deep, concave posteromedian excavation. Gonocoxite short, stout, 1.25 x longer than broad, apex broad, sinuate; gonostylus 1.2 x longer than gonocoxite, broadest on proximal 1/5, tapering gradually distally, distal 2/3 slightly curved, apex rounded. Parameres ( Fig. 31 ) separate, moderately slender, somewhat boomerang-shaped; basal apodeme with elongate anterior arm, apical 1/3 curved, posterior arm shorter with slightly expanded blunt apex; distal portions moderately short, curved distally, apices pointed, divergent. Aedeagus ( Fig. 32 ) triangular; basal arch very low, slightly concave; basal arm heavily sclerotized, slender, nearly straight, laterally directed with blunt apex; distal portion barely discernible, lightly sclerotized, tapered distally, apex rounded.

Allotype female. Head ( Fig. 16 ) mostly dark brown. Eyes barely contiguous on extreme lower portions, with sparse interommatidial spicules. Antennal pedicel dark brown, flagellum light brown; flagellomeres 2-8 ( Fig. 17 ), moderately short, barrel-shaped, 9-13 elongate, cylindrical, 13 longest; flagellomeres 8, 12 with single subapical sensillum coeloconicum; antennal ratio 1.19. Clypeus with 3 pairs of setae. Palpus ( Fig. 17 ) light brown; segment 3 moderately stout, with broad, shallow, subapicomesal sensory pit; palpal ratio 2.16. Mandible with 8 coarse teeth. Thorax. Scutum uniformly brown; scutellum pale with 6-7 large, 8 smaller setae. Femora, tibiae slender, uniformly brown (mid tibiae, tarsi missing), tarsi slightly paler; tarsomere 1 of fore, hind legs with ventral basal, apical spines; hind tarsomeres 1̄2 with two rows of ventral palisade setae, apparently with moderately numerous large setae (only insertions remain); hind tibial comb with 6 spines; hind tibial ratio 7.60; hind tarsal ratio 1.80; tarsomere 4 of fore leg short, cordiform, tarsomere 4 of hind leg elongate, cylindrical; claws small, equal size on fore leg, hind leg with single long claw that is slightly longer than tarsomere 5 with a stout basal tooth about 1/3 as long as claw. Wing ( Fig. 18 ) membrane infuscated, particularly in radial sector, distal 2/3 of cell r3 and along veins; two well developed radial cells, 2nd broader, slightly longer than 1st; macrotrichia numerous on distal 2/3 of membrane, particularly dense on distal half of cell r3, and margins of m1, m2, about 40 on distal ½ of anal cell; wing length 1.16 mm, width 0.47 mm; costal ratio 0.60. Halter missing. Abdomen ( Fig. 19 ) dark brown. Sternite 8 with V-shaped posteromedian cleft; sternite 9 halves moderately broad with rounded apices. Sternite 10 with two pairs of setae. Two unequal spermathecae; the larger pyriform with short, broad truncate neck, measuring 75 µm by 42 µm; the smaller partially collapsed with short narrow neck; a rudimentary third spermatheca present.

Type material. Holotype male, ARGENTINA, Neuquen, Parque Nacional Nahuel Huapi, mallin La Heladera , 41°00'56.0"S, 71°49'45.40"W, 878m, 7-I-2007 / 4-II- 2 0 0 7, A. Garré ̄ F. Montes de Oca, Malaise trap ( MLPA) ; allotype female, Neuquen, Parque Nacional Nahuel Huapi, laguna Los Clavos , 41°04'48.6"S, 71°49'33.9"W, 1194m, 5-II-2007 / 3-III- 2 0 0 7, A. Garré ̄ F. Montes de Oca, Malaise trap ( MLPA) .

Distribution. Known only from the type locality, the Nothofagus forests of the Nahuel Huapi National Park of Neuquen province, Argentina ( Fig. 35 ).

Derivation of the specific epithet. We are pleased to name this new species after our colleague Augusto Siri, at the Instituto de Limnología “Dr. Raúl A. Ringuelet”, La Plata, Argentina, in recognition of his important contributions to the taxonomy of Chironomidae in the Neotropical Region, and for his valuable collections of Ceratopogonidae from Argentina during the past 10 years.

Discussion. This new species is readily distinguished from its Neotropical congeners by its small size and the well-defined sensory pit on palpal segment 3. The male gonocoxite is very short, stout and lacks a basomesal tubercle; the gonostylus is much longer than the gonocoxite; and, the aedeagus is small, lightly sclerotized with a very low slightly concave basal arch, the apex is rounded and lacks a distal extension. The female wing membrane has dense, coarse macrotrichia and the spermathecae are pyriform, unequal, with short, broad truncate necks.

Two other species from Australasia also have a sensory pit on palpal segment 3. In his original description of A. tonnoiri from New Zealand, Macfie (1932) stated “…third (palpal segment) not inflated, bearing sensory hairs on a depressed area on apical third” and Tokunaga (1964) noted for A. campbellensis from Campbell Island, that palpal segment 3 is “…slightly thickened, with very small sensory pore on apical 1/3.”

Figures

FIGURE 35. Map of Argentine and Chilean Patagonia with distribution records of: Austrohelea shannoni (Wirth & Blanton), green circles. Austrohelea sirii n. sp., yellow triangles. Austrohelea spinosa n. sp., red diamonds.

FIGURES 13 – 15. Austrohelea sirii n. sp. Male. 13. head. 14. wing. 15. genitalia.

FIGURES 29 – 34. Austrohelea shannoni (Wirth & Blanton). Male. 29. parameres. 30. aedeagus. Austrohelea sirii n. sp. Male. 31. parameres. 32. aedeagus. Austrohelea spinosa n. sp. Male. 33. parameres. 34. aedeagus.

FIGURES 16 – 19. Austrohelea sirii n. sp. Female. 16. head. 17. palpi and mouthparts. 18. wing. 19. abdominal segments 7 – 9 and spermathecae.