Stigmella huahumi Remeikis & Stonis, sp. nov.

(Figs 1, 95–101)

Type material. Holotype: ♂, ARGENTINA, Neuquen Province, Lago Lacar, 5 km E of Hua-Hum, elevation ca. 640 m, 25.xi.1981, Nielseni & Karsholt, genitalia slide no. RA 629♂ (ZMUC) .

Paratype: 1 ♂, same label as holotype, genitalia slide no. RA630♂ (ZMUC).

Diagnosis. The combination of an unique set of cornuti in the phallus (see Fig. 101), long arms and triangular processes of transtilla (see Figs. 99, 100), very slender processes of gnathos, unique shape of valva and uncus (see Fig. 98), and a pale brownish grey forewing distinguishes S. huahumi sp. nov. from all other Stigmella species.

Male (Figs 95–97). Forewing length 2.8–3.0 mm; wingspan 6.0– 6.5 mm. Head: palpi and frontal tuft grey cream; collar and scape silvery cream; antenna longer than half the length of forewing; flagellum with 37–38 segments, brownish cream to pale brown on upper side and underside. Thorax, tegula and forewing glossy, brownish cream to pale brownish grey; apical half of forewing little speckled with very pale brown scales; fringe and underside of forewing pale brownish grey. Hindwing pale brownish grey with very little purple iridescence on upper side, without spots or androconia on upper side or underside; its fringe pale brownish grey. Legs brownish cream, glossy; forelegs darkened with grey-brown scales on upper side. Abdomen dark grey, shiny on upper side, grey to dark grey on underside; genital segments pale brown to cream; anal tufts pale brown to grey cream.

Female. Unknown.

Male genitalia (Figs 98–101). Capsule longer (300–305 µm) than wide (170 µm). Uncus with two unusually shaped lobes (Figs 98, 99). Gnathos with two very slender caudal processes. Valva 190–195 µm long, 65–75 µm wide, with two apical processes; transtilla with very long arms and triangular, weakly developed sublateral processes. Vinculum with short, widely rounded lateral lobes. Phallus (Fig. 101) 195–230 µm long, 80–95 µm wide; vesica with about 7 bilateral spine-like cornuti.

Bionomics. Adults fly in November. Otherwise biology unknown.

Distribution (Figs 1). This species occurs in the southern Andes (Argentina: Neuquen Province) at altitudes around 640 m.

Etymology. The species is named after the type locality (Hua-Hum, along Río Huahum which connects two lakes: Lago Nonthue, Argentina, and Lago Pirihueico, Chile).