Tribasodites, Jeannel, 1960

Zhang, Yong-Qin & Yin, Zi-Wei, 2025, The ant-like litter beetle fauna from the Wumenshan National Nature Reserve, China, with description of eight new species (Staphylinidae: Pselaphinae), European Journal of Taxonomy 1007, pp. 133-162 : 147-150

Tribasodites ocellus sp. nov.

Chinese common name: 小眼ẘḃü甲 urn:lsid:zoobank.org:act:33F969AF-08C4-4E15-97AF-967347498CC3 Fig. 5

Diagnosis

Male

Body. Elongate, length approximately 2.4 mm. Head subglobose, slightly narrower than pronotum, vertex lacking sulcus, with small, asetose foveae; eyes small; antenna moderately elongate, lacking modifications. Pronotum lacking marginal spines, with distinct lateral longitudinal sulci, with one pair of short antebasal spines. Discal striae extending posteriorly to approximately 3 /10 of elytral length. Mesotrochanter with distinct ventral spine; metatrochanter with hook-like projection. Aedeagus elongate, asymmetric; median lobe with moderately large capsule and rounded foramen, ventral stalk dorsoventrally broad, apically twisted to form large apical plate, dorsal lobe elongate plate-like, embracing endophallus armature which is split apically into two lobes, parameres broadened, slightly sclerotized in lateral portions.

Female

Unknown.

Etymology

The specific epithet is a Latin noun meaning ‘little eye’, indicating the small compound eyes of this species. The name is a nominative singular noun in apposition.

Type material

Holotype

CHINA • ♂; Yunnan, Zhaotong City, Wumengshan Conservation Area, Luohanba , Chechangping ; 27°33′15″ N, 104°1′32″ E; 1573 m a.s.l.; 17 Jul. 2022; Wei leg.; Ǖ南乌®山罗ḋữţ广ū, 魏ǡ豪 *; SNUC.

Description

Male

BODY ( Fig. 5A ). Length 2.41 mm; colour dark reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with dense pubescence.

HEAD ( Fig. 5B ). Subglobose, rounded at base, slightly wider than long, length 0.42 mm, width 0.48 mm; vertex finely punctate, with small, asetose vertexal foveae (dorsal tentorial pits), lacking sulcus and mediobasal carina, lacking lateral postantennal carinae; frons demarcated from clypeus by thin, oblique carinae, area between moderately raised antennal tubercles impressed; clypeus with smooth surface, its entire anterior margin strongly carinate and moderately raised; ocular-mandibular carinae thin, complete. Venter with smooth surface; small gular foveae (posterior tentorial pits) originating from shared oval opening, with thin median carina extending from opening anteriorly to mouthparts. Compound eyes small, each composed of approximately 10 ommatidia. Antenna elongate, length 1.21 mm, indistinct club ( Fig. 5C ) loosely formed by slightly enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–7 each elongate, 8 shortest, 9 wider and longer than 8, 10 slightly shorter than 9, 11 largest, as long as 9 and 10 combined (24:24), subconical.

PRONOTUM ( Fig. 5B ). Slightly longer than wide, length 0.47 mm, width 0.45 mm, widest anterior to middle; lateral margins rounded, convergent basally and parallel at basal ¼; disc moderately convex, finely punctate, lacking median longitudinal sulcus, with oval antebasal impression and short mediobasal carina, with pair of short discal carinae present at basal half of disc, with thin lateral longitudinal sulci; with one pair of short antebasal spines; lateral antebasal foveae distinct and setose; lacking outer and inner pair of basolateral foveae. Prosternum with basisternal (precoxal) portion slightly longer than procoxal rests, with small lateral procoxal foveae; hypomeral grooves obliquely extending from base anteriorly for almost entire length of hypomeron, with lateral antebasal hypomeral impressions, hypomeral ridges close to margins of coxal cavities, extending anteriorly to meet hypomeral grooves.

ELYTRA. Much wider than long, length 0.67 mm, width 0.79 mm; each elytron with three small, asetose basal foveae; discal striae extending posteriorly from outer basal fovea to 3 / 10 of elytral length; humeri lacking prominence or denticle, subhumeral foveae small, carinate marginal striae extending from foveae to posterior margins of elytron. Metathoracic wings reduced.

MESOVENTRITE. Short, demarcated from metaventrite by oblique ridges; median mesoventral foveae slightly separated, originating from shared setose, transverse opening, large lateral mesoventral foveae forked internally; prepectus massive, collar-shaped; mesoventral intercoxal process short, apically acute, marginal striae complete. Metaventrite slightly impressed at middle, with pairs of lateral mesocoxal and close lateral metaventral foveae, metaventral intercoxal process with small and narrow split at middle.

LEGS. Elongate; mesotrochanter ( Fig. 5D ) with distinct ventral spine; metatrochanter with hook-like projection ( Fig. 5E ) on ventral margin, mesal margin of metatibia with row of stiff setae at apical portion.

ABDOMEN. Widest at lateral margins of tergite 1 (IV), length 0.82 mm, width 0.72 mm. Tergite 1 (IV) at middle slightly shorter than 2 (V) and 3 (VI) combined and twice as long as 2, thin basal sulcus interrupted by one pair of mediobasal and two pairs of basolateral foveae, with pair of short discal carinae, oblique inner marginal carinae complete, lacking outer carinae; tergite 2 (V) shorter than 3 (VI), 4 (VII) shorter than tergites 2 and 3 combined, with pair of small lateral nodules; 2–4 (V–VII) each with one pair of small basolateral foveae and thin marginal carinae; tergite 5 (VIII) semicircular, transverse, posterior margin roundly emarginate at middle. Sternite 2 (IV) with one pair of mediobasal and three pairs of basolateral foveae, lacking lateral carinae; midlength of sternites 2–5 (IV–VII) gradually shorter, 3 with two pairs of small basolateral foveae and short carinae, 4 and 5 each with one pair of small basolateral foveae, sternite 6 (VIII) transverse, impressed at middle, posterior margin broadly emarginate, sternite 7 (IX) with paired membranous structure.

AEDEAGUS ( Fig. 5F–G ). 0.53 mm long, asymmetric, elongate; median lobe with moderately large basal capsule and rounded foramen, ventral stalk dorsoventrally broadened, with transverse protuberance at base, apically greatly twisted to form large, broad apical plate with pointed apex; dorsal lobe elongate, plate-like, embracing endophallus armature, which comprising elongate sclerite split into two parts at apex, parameres broad, weakly sclerotized in lateral portions, membranous at middle.

Female

Unknown.

Remarks

This species may represent a derived form among those characterized by a plate-like dorsal lobe of the aedeagus that embraces the endophallus armature. The absence of marginal spines on the pronotum is also a rare, though not unprecedented, feature within the genus. The new species can be readily identified by its small eyes, the lack of distinct male sexual characters, and the unique structure of the aedeagus.

Distribution

Southwest China: Yunnan.

Figures

Fig. 5. Tribasodites ocellus sp. nov., holotype, ♂ (SNUC). A. Dorsal habitus. B. Head and pronotum. C. Antennal club. D. Mesotrochanter. E. Metatrochanter. F. Aedeagus, lateral view. G. Aedeagus, ventral view. Scale bars: A = 0.5 mm; B, D–E = 0.3 mm; C = 0.2 mm; F–G = 0.1 mm.