Oxyethira (Dactylotrichia) acuminata, Neto & Ribeiro & Passos, 2023

Neto, Jaime De Liege Gama, Ribeiro, José Moacir Ferreira & Passos, Mahedy Araujo Bastos, 2023, Three new Oxyethira Eaton 1873 (Trichoptera: Hydroptilidae) from Pará State, Northern Brazil, Zootaxa 5330 (1), pp. 126-134 : 131-133

Oxyethira (Dactylotrichia) acuminata sp. nov.

( Figs 5A–5D )

Diagnosis. This new species belongs to subgenus Oxyethira (Dactylotrichia) as recognized by segment VIII having its venter excised nearly to its anterior end and its dorsum without dorsolateral processes; segment IX having its venter produced anteriorly into segment VII; the inferior appendages elongate and separate basally; the subgenital plate arms fused basally and apically; and the phallus without a titillator ( Kelley 1984). This new species ressembles Oxyethira (Dactylotrichia) baritu Angrisano 1995 in the similarly shaped sternum IX, subgenital plate, and phallus, but can be distinguished by the shape of the anterior margin of segment IX, by the inferior appendages, and by the phallus apex. Segment IX of the new species has anterior margin slightly acute in ventral view, while in O. baritu segment IX anterior margin is round. The inferior appendages of the new species are each separate and acute apically, while in O. baritu the inferior appendages are each digitiform. The phallus apex of the new species is twisted and acute, while in O. baritu the phallus apex is hooked.

Description. Male (in alcohol). Dark brown species. Length of each forewing 1.75 mm (holotype and paratype, n = 2). Head unmodified, with 3 ocelli; antennae with 27 segments terete. Tibial spur count 1-3-4. Dorsum of head with dark setae; thorax with pale yellow setae dorsally, light brown ventrally; leg segments with light brown setae. Forewings covered with fine yellow setae and small scattered patches of dark brown setae. Sternum VII with posterior mesoventral process.

Male genitalia. Segment VIII annular; sternum VIII with V-shaped posteromesal incision nearly to anterior margin ( Fig. 5B ); tergum VIII posterior margin irregular and oblique in lateral view, with pair of dorsomesal lobes covered by microtrichia ( Fig. 5C ). Segment IX retracted into segment VIII; sternum IX produced anteriorly and reaching into posterior area of segment VII ( Figs 5A–5C ). Segment X indistinct. Subgenital plate beak-like, downturned posteriorly ( Fig. 5A , sg); in both ventral and dorsal views with distal arms fused ( Figs 5B, 5C , sg). Bilobed process a pair of elongate, slender processes, each with short, hooked apical seta ( Figs 5A–5C , bp). Inferior appendages in lateral view tapering, acute apically, and each with dorsal membranous process bearing one long apical seta ( Fig. 5A , ia); in ventral view fused basally, then separated, divergent, triangular, and apically acute ( Fig. 5B , ia). Phallus simple, elongate; phallus apex twisted, acute and covered by membrane ( Fig. 5D ); ejaculatory duct not protruding ( Fig. 5D , ed).

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).

Paratype. 1 male, same data as for holotype .

Distribution: Brazil (Pará, type locality only).

Etymology. The Latin epithet “acuminata” refers to the inferior appendages each apically pointed.

Figures

FIGURE 5. Oxyethira acuminata sp. nov., male genitalia. 5A, left lateral; 5B, ventral; 5C, dorsal; 5D, phallus (left lateral). bp = bilobed process, ed = ejaculatory duct, ia = inferior appendage (paired), sg = subgenital plate.