Oxyethira (Tanytrichia) longisterna Neto & Ribeiro & Passos 2023, sp. nov.

Oxyethira (Tanytrichia) longisterna sp. nov.

(Figs 3A–3D)

Diagnosis. This new species belongs to subgenus Oxyethira (Tanytrichia) as recognized by segment VIII lacking dorsolateral processes, sternum VIII excised to its anterior margin, and sternum IX elongate and protruding anteriorly into segment VI (Kelley 1984). This new species is similar to Oxyethira una Souza & Santos 2017 by having similarly shaped anterior margin of tergum X and inferior appendages, but can be distinguished by the tergum VIII posterior margin and by the phallus apex. The tergum VIII posterior margin of the new species, in dorsal view, is concave, while in O. una the tergum posterior margin has a deep median incision. The phallus apex of the new species is covered by membrane, while in O. una the phallus apex is simple and without membrane.

Description. Male (in alcohol). Dark brown species. Length of each forewing 1.75 mm (n = 1). Head unmodified, with 3 ocelli; antennae of holotype broken and lost. Tibial spur count 1-3-4. Dorsum of head with brown setae; thorax with brown setae dorsally, light brown ventrally; leg segments with light brown setae. Forewings covered with fine brown setae and small scattered patches of dark brown setae. Sternum VII with posterior mesoventral process.

Male genitalia. Segment VIII annular, posterior margin produced into pair of ventrolateral lobes (Fig. 3A); sternum VIII in ventral view deep incised medially, posterolateral margins widely separated and narrowing to blunt apices (Fig. 3B); tergum VIII posterior border concave, posterolateral margins narrowing to blunt apices (Fig. 3C). Segment IX retracted in segment VIII; sternum IX in lateral view produced and tapering anterad into mid-length of segment VI (Figs 3A–3C), posterior margin obliquely truncate and produced posteriorly at mid-height (Fig. 3A). Tergum X membranous, oblong in lateral view (Fig. 3A), apically round in dorsal view (Fig. 3C). Subgenital plate in lateral view round anteriorly, tapering to acute posterior process (Fig. 3A, sg); in dorsal and ventral views, produced into acute posteromesal process (Figs 3B, 3C, sg). Bilobed process fused basally, its arms widely divergent and each with long and curved apical seta (Figs 3A, 3B, bp). Inferior appendages sclerotized, tapering in lateral view (Fig. 3A, ia); in ventral view fused to each other basomesally, produced into pair of blunt lobes (Fig. 3B, ia). Phallus simple, slender; its apex covered by membrane; twisted, apical spine protruding from membrane; ejaculatory duct extending to phallus apex, not protruding (Fig. 3D).

Female, larva, pupa, and egg. Unknown.

Holotype male. BRAZIL: Pará: S„o Geraldo do Araguaia municipality, Serra das Andorinhas, Santa Cruz stream, 06°13’31.1”S / 48°26’28.1”W, 124 m, 18–31 Oct. 2019. Pennsylvania light trap, J.M.F. Ribeiro, leg. (UEMA).

Distribution: Brazil (Pará, type locality only).

Etymology. The epithet “longisterna” refers to sternum IX, which is very long anteroventrally.