Bibrax longiventer, Tapuy-Avilés & Díaz-Guevara & Caterino, 2025

Tapuy-Avilés, Yarina, Díaz-Guevara, David R. & Caterino, Michael S., 2025, First record of Bibrax Fletcher, 1927 (Coleoptera, Staphylinidae, Pselaphinae) from Ecuador, with descriptions of twelve new species, ZooKeys 1250, pp. 105-133 : 105-133

Bibrax longiventer sp. nov.

Figs 2 I, J , 4 A – D

Type material.

Holotype • ♂ ( MECN -EN 40723 ): “ Ecuador: Napo, -0.61523, -77.59071, Archidona, Pacto Sumaco , 1805 m, 27.IX.2024, A. Pazmiño & D. Díaz, Winkler ” / “ Caterino DNA voucher, Ext. MSC-13068, Morphosp. VS.007 ” / “ MECN -EN 40723 ” . Paratypes (2 ♂ 2 ♀) • same data as type ( MECN -EN 40639 , 40608, 40651, 40655) .

Diagnosis.

BL = 1.88 mm (n = 3). Body rather large, densely setose, reddish-orange; eyes of both sexes strongly reduced, borne on small prominence, comprising two or three indistinct ommatidia; head subquadrate posteriorly, prolonged in front of eyes to prominent antennal base, deeply depressed at vertexal foveae, slightly elevated posteriorly; antennal scape sinuate, narrowed to base and before apex, flagellomeres II – VI progressively shorter, VII slightly larger, VIII small, IX – XI forming weak, loose club; gular teeth not prominent; pronotum with lateral lobes strongly produced, rounded, pronotum strongly constricted posteriorly; median and lateral longitudinal pronotal impressions well developed; elytra rather short, with narrowed humeri (flightless), each with sutural and one lateral basal foveae, lateral fovea with short longitudinal impression extending posterad; abdominal paratergites wide; protibia swollen; male metaventrite with small flat glabrous area between and anterad metacoxae; male abdominal segment 5 markedly elongate, sternite especially, prolonged anterad into emarginate ventrite 4, deeply concave, with small, tubular denticle at basal margin; legs without obvious secondary sexual characters. Aedeagus (Fig. 2 I, J ) with basal bulb large, basally truncate, dorsally angulate, with long basal apodeme; tegmen comprising two separate processes, a shorter, strongly arched and apically acute rod on left side; right-side process longer, terminating in dorsoventrally flattened, subrectangular plate.

Distribution.

This species is known only from the isolated Volcan Sumaco, in the western Amazonian basin, Ecuador.

Remarks.

The remarkably prolonged male sternite 5 in this species is unique among known Bibrax , while the strongly laterally lobed (and posteriorly constricted) pronotum may also help distinguish females from those of other species. While among the ‘ smaller’, flattened species described herein, this species is also larger than most others.

Etymology.

The name of this species refers to the uniquely elongate last abdominal ventrite.

Figures

Figure 2. Aedeagus of Bibrax species, lateral view (A, C, E, G, I, K) and dorsal view (B, D, F, H, J, L). A, B. B. chullachaqui sp. nov.; C, D. B. chocoensis sp. nov.; E, F. B. onorei sp. nov.; G, H. B. aratrifer sp. nov.; I, J. B. longiventer sp. nov.; K, L. B. cerroblanco sp. nov.

Figure 4. Habitus of Bibrax species (A, E. Dorsal view; B, F. Lateral view; C. Ventral view; D, H. Male abdominal ventrites; G. Venter of head). A – D. B. longiventer sp. nov.; E – H. B. cerroblanco sp. nov.