Batriscenaulax wangluyui He & Yin, 2025

He, Dong-Yu & Yin, Zi-Wei, 2025, A new species of Batriscenaulax Jeannel, 1958 (Coleoptera: Staphylinidae: Pselaphinae) from Jinfoshan Nature Reserve, southwest China, Zootaxa 5728 (2), pp. 395-400 : 396-398

Batriscenaulax wangluyui He & Yin , sp. nov.

( Fig. 1 )

Type material. HOLOTYPE: CHINA: ♂, ‘China: Chongqing, Nanchuan District, Mt. Jinfo, Lanbaqing , Sanchagou , 29°01'03"N, 107°08'45"E, 1400 m, 2.ix.2024, J.-K. Chang, D.-Y. He leg., ĦṄẆ南nj区Ễ佛ƜHŇ 保Ê区Ȅ坝ª三ĖÁ ’ ( SNUC) . PARATYPES: CHINA: 40 ♂♂, 66 ♀♀, same collection data as for holotype. ( SNUC) .

Diagnosis. Male. Body length approximately 2.0– 2.1 mm. Head sub-rectangular, roundly truncate at base; vertex finely punctate, with shallow, reverse U-shaped impression connecting foveae. Pronotum with median longitudinal sulcus as long as semicircular lateral sulci in dorsal view. Elytra with curved discal striae extending posteriorly for approximately 7/10 elytral length. Protibia in dorsal view evenly broadened apically, with densely setose apex; protrochanter with small ventral tubercle. Tergite 1 (IV) greatly modified, with large central cavity of complex structures and trichomes inside and along margins; anterolateral margins roundly expanded, each side with two exceptionally long macrosetae directed posterolaterally; area mesal to expansions impressed. Aedeagus asymmetric, median lobe with constricted basal capsule and small foramen; ventral stalk broad throughout, much longer than dorsal lobe, in ventral view pointed toward apex; dorsal lobe broadened in lateral view, with membranous spine-like structures at middle; parameres reduced to broad, semi-membranous structure. Female. Body length approximately 1.9–2.0 mm; legs and abdomen simple, unmodified; genitalia with genital plate slightly wider than posterior lobe of sternite 7 (IX).

Description. Male. Body ( Fig. 1A ) length 2.03–2.09 mm; color red brown, antennae, tibiae, tarsi and mouthparts lighter. Dorsal, ventral surfaces with relatively dense, short pubescence.

Head ( Fig. 1B ) sub-rectangular, roundly truncate at base, slightly broader than long, length 0.43–0.45 mm, width 0.48–0.51 mm; vertex finely punctate; with large, asetose vertexal foveae (dorsal tentorial pits); shallow, reversed U-shaped impression connecting foveae; mediobasal carina short, faint; tempora shorter than eyes, roundly convergent posteriorly; antennal tubercles moderately raised; frons broadly, slightly impressed medially, confluent with clypeus; clypeus smooth, anterior margin carinate and moderately raised; ocular-mandibular carina distinct, nearly complete, extending from area below eyes to posteroventral articulation of mandible. Venter with small gular foveae (posterior tentorial pits) narrowly separated, in single oval impression; with thin, distinct median carina extending from impression anteriorly to mouthparts. Eyes prominent from lateral profile, each composed of approximately 30 large ommatidia. Maxillary palpus with palpomere 1 minute; 2 elongate, curved, pedunculate basally, enlarged apically; 3 short, sub-trapezoidal; 4 fusiform, widest in basal one-third, with tiny apical cone. Antenna moderately elongate, length 1.31–1.38 mm; club loosely formed by three enlarged apical antennomeres, lacking modifications; antennomere 1 thick, subcylindrical; 2–8 each elongate; 10 as long as 9, slightly broader; 11 longest, slightly shorter than 9, 10 combined (27:30), sub-fusiform.

Pronotum ( Fig. 1B ) approximately as long as wide, length 0.51–0.52 mm, width 0.51–0.53 mm, widest at middle; lateral margins rounded; semicircular lateral sulci extending from dorsal surface laterally and posteriorly, then fused with lateral ends of antebasal sulcus; disc moderately convex, finely punctate, median longitudinal sulcus approximately as long as semicircular lateral sulci; median antebasal fovea lacking; with short mediobasal impression; with complete transverse antebasal sulcus connecting lateral antebasal foveae; inner and outer pairs of basolateral foveae distinct. Prosternum with basisternal (precoxal) portion longer than procoxal rests, with wellseparated, asetose lateral procoxal foveae; hypomeral grooves oblique, present only on basal half of hypomeron, with distinct lateral antebasal hypomeral pit; hypomeral ridges close to coxal cavities.

Elytra much wider than long, length 0.74–0.77 mm, width 0.86–0.91 mm; each elytron with two small, asetose basal foveae; discal striae thin, distinctly curved, extending from outer foveae posteriorly to approximately 7/10 of elytral length; humeri roundly prominent; subhumeral foveae absent, with sulcate marginal striae extending from approximately basal two-fifths to posterior margins. Metathoracic wings fully developed.

Mesoventrite short, laterally fully demarcated from metaventrite by oblique ridges; median mesoventral foveae widely separated, originating from shared setose, transverse opening; lateral mesoventral foveae large, setose, forked internally; prepectus massive, collar-shaped; mesoventral intercoxal process short, apically moderately acute. Metaventrite slightly impressed at middle, with large, setose lateral mesocoxal foveae and pair of smaller, setose lateral metaventral foveae, metaventral intercoxal process with small, narrow slit at middle.

Legs elongate; protrochanter and protibia weakly modified. Protrochanter ( Fig. 1C , indicated by arrow) with small ventral tubercle; protibia ( Fig. 1D ) evenly and moderately broadened from middle to apex, apically densely setose, brush-like; other leg parts simple.

Abdomen widest at basolateral margins of tergite 1 (IV), length 0.47–0.55 mm, width 0.65–0.93 mm. Tergite 1 (IV) ( Fig. 1E ) heavily modified, much longer than tergites 2–4 (V–VII) combined; with inner basolateral foveae embracing thin basal sulcus and pair of outer basolateral foveae; with short, triangular discal carinae; basolateral margins roundly expanded laterally, area mesal to expansions broadly impressed; with broad, transverse median cavity; anterior margin of cavity with pair of setose tufts, with small, T-shaped tubercle bearing paired tufts inside cavity; posterior part of cavity with large, roundly triangular projection; each side of tergite ( Fig. 1F ) with two long, posterolaterally-directing macrosetae; 2 (V), 3 (VI) short, subequal along middle; 4 (VII) slightly longer than 2, 3 combined; 2–4 each with one pair of small basolateral foveae; tergite 5 (VIII) semicircular, posterior margin rounded, weakly, broadly emarginate at middle. Sternite 2 (IV) with one pair mediobasal and three pairs basolateral foveae, lateral pair developing into large sockets; lacking discal carinae; midlength of sternite 4 (VI) approximately as long as 2, 3 combined; 3–5 each short at middle, lacking foveae; 6 (VIII) transverse, posterior margin sinuate; 7 (IX) ( Fig. 1G ) moderately sclerotized for apical 1/3, basal 2/3 membranous, with rounded posterior margin.

Aedeagus ( Fig. 1H, I ) 0.32 mm long, asymmetric; median lobe moderately sclerotized, with relatively small basal capsule and small reversed trapezoidal foramen; with long basoventral projection; ventral stalk elongate, in lateral view broadened in apical part, in ventral view pointed toward apex; dorsal lobe in lateral view distinctly broadened, in ventral view elongate and with round apex, laterally with membranous, spine-like structures; parameres fused, reduced to broad, slightly sclerotized membrane.

Female. Externally similar to male in general. Each eye composed of approximately 25 ommatidia. Antenna slightly shorter. Elytral base more distinctly constricted; humeri less prominent; metathoracic wings reduced. Legs and abdomen simple. Genitalia ( Fig. 1J ) 0.28 mm wide; posterior lobe of sternite 7 (IX) broadly T-shaped, with extended lateral arms; anterior lobe narrow, composed of paired elongate axe-shaped plates; genital plate transverse, curved at middle, slightly wider than sternite 7 (IX), with pair of slender lateral arms each thickened before apex, narrowing apically. Measurements (as for male): body length 1.92–2.02 mm; length/width of head 0.41–0.42 mm / 0.47 mm, pronotum 0.46–0.47 mm / 0.46–0.47 mm, elytra 0.65–0.69 mm / 0.77–0.79 mm, abdomen 0.51–0.64 mm / 0.73–0.76 mm; antennal length 1.21–1.24 mm.

Comparative notes. The genus Batriscenaulax Jeannel, 1958 was originally established based on Japanese species ( Jeannel 1958; Nomura 1991) and subsequently expanded through the addition of two Chinese congeners ( Yin 2022, 2024). Japanese members are distinctly smaller ( 1.4–1.6 mm) and putatively constitute a monophyletic group linked by a unique male protibial modification: a setose brush situated at the apex of an expansion on the apicolateral margin. By contrast, the two known Chinese species, B. campestris Yin, 2022 (ca. 1.8 mm) from Xizang and B. shennongjia Yin, 2024 (ca. 2.3 mm) from Hubei, are distinctly larger and possess male protibial modifications differing in shape and placement. Batriscenaulax campestris exhibits a triangular setose brush on the apicomesal margin of the protibia along with abdominal modifications, whereas B. shennongjia bears a medially thickened protibia and an unmodified abdomen. Batriscenaulax wangluyui sp. nov. can be readily separated from all Japanese and Chinese congeners by the combination of slightly broadened male protibiae, the heavily modified and laterally expanded first visible tergite (IV), and the unique configuration of the aedeagus.

Distribution. Southwest China: Chongqing.

Etymology. The epithet is a noun in the genitive singular, formed as a patronym derived from Lu-Yu Wang in recognition of his invaluable support during the collection of the type series.

Figures

FIGURE 1. Habitus and morphological details of Batriscenaulax wangluyui sp. nov. (A–I. Male. J. Female). A. Dorsal habitus. B. Head and pronotum. C. Protrochanter, arrow indicates ventral tubercle. D. Apical portion of protibia. E. Tergite 1 (IV). F. Lateral macrosetae on tergite 1 (IV). G. Sternite 7 (IX). H, I. Aedeagus, ventral (H), and lateral (I). J. Genital complex. Scale bars: 0.5 mm in A; 0.3 mm in B, E; 0.1 mm in C, F–H, J; 0.2 mm in D; 0.05 mm in I.