Bryaxis diaoluomontis, Yin, 2023

Yin, Zi-Wei, 2023, A new species of Bryaxis Kugelann from tropical China (Coleoptera: Staphylinidae: Pselaphinae), Zootaxa 5228 (5), pp. 595-598 : 595-597

Bryaxis diaoluomontis sp. nov.

( Fig. 1 )

Chinese common name: ĦƤDzoiẘm

Type material. HOLOTYPE: CHINA: ♁: ‘ China : Hainan, Lingshui County, Diaoluoshan N. R., 18°43′46.81″N, 109°51′38.52″E, 900–1250 m, 11–12.xi.2022, Cai & Zhou leg., [ṘNJĦƤffikae‵fflffi]’ ( SNUC).

Diagnosis. Male. Body length slightly less than 1.5 mm; dorsal surface covered with long pubescence. Head and pronotum roughly punctate, elytra with punctation much sparser and shallower. Vertex with thin median ridge. Antennomere 1 greatly enlarged, swollen and roundly angulate at anteromesal margin. Aedeagus stout; parameres narrowed at apices; endophallus armature mainly composed of two elongate sclerites.

Description. Male. Body ( Fig. 1A ) length 1.46 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with long, sub-erected pubescence.

Head ( Fig. 1B ) truncate-triangular, rounded at base, slightly wider than long, length 0.29 mm, width across eyes 0.32 mm; vertex moderately convex at middle, coarsely punctate, with small, asetose vertexal foveae (dorsal tentorial pits), with thin but distinct median longitudinal ridge; antennal tubercles moderately raised; frons broadly impressed medially, confluent with clypeus; clypeus descending, sparsely punctate, anterior margin carinate and moderately raised; ocular-mandibular carina complete. Gula prominent ventrally, with two small gular foveae (posterior tentorial pits) in transverse slit, with thin median carina extending from foveae anteriorly to mouthparts. Eyes prominent, each composed of approximately 40 ommatidia. Maxillary palpus greatly elongate, palpomere 1 minute, 2 lengthily pedunculate at base, swollen at apex, 3 slightly elongate, narrowed at base and slightly broadened at apical half, 4 with short stem at base, then broadened through entire length, length 0.22 mm, width 0.07 mm. Antenna pubescent, relatively short, length 0.56 mm, club formed by enlarged apical three antennomeres; antennomere 1 (scape) ( Fig. 1C ) 0.14 mm long and 0.10 mm wide, distinctly swollen, lacking glandular protuberance, mesal margin roundly angulate at apical 1/3, antennomere 2 (pedicel) ( Fig. 1C ) 0.06 mm long, lacking modification, 3 to 8 each moniliform, 9 and 10 transverse, successively larger, 11 large, sub-fusiform, truncate at base.

Pronotum ( Fig. 1B ) coarsely punctate, wider than long, length 0.31 mm, width 0.37 mm, widest at middle; sides rounded; disc weakly convex, area around lateral antebasal foveae impressed, with transverse antebasal sulcus connecting foveae, with short mediobasal carina. Hypomeral ridge complete, lacking hypomeral pit. Prosternum with anterior part distinctly longer than coxal part, with small lateral procoxal foveae; margin of coxal cavity broadly carinate.

Elytra much wider than long, length 0.52 mm, width 0.61 mm, disc shallowly and sparsely punctate, punctures large; each elytron with two large, asetose basal foveae, lacking subbasal fovea; discal stria shallow and short; humeral protuberance small, angulate, subhumeral fovea distinct, with marginal carina extending from fovea to posterior margin of elytron; cleft angulate. Metathoracic wings fully developed.

Mesoventrite short, demarcated from metaventrite by ridged anterior margins of impressed areas where large, setose lateral mesocoxal foveae situated at mesal portions of impressions, with pair of thin admesal carinae; setose median mesoventral foveae narrowly separated, lateral mesoventral foveae large and setose, unforked internally; intercoxal process long, bluntly rounded at apex. Metaventrite flat at middle, with broadly-separated lateral metaventral foveae, posterior margin straight, lacking split at middle.

Legs moderately short, simple.

Abdomen compressed, widest at lateral margins of tergite 1 (IV), length 0.34 mm, width 0.51 mm. Tergite 1 (IV) in dorsal view slightly longer than 2 (V), basally sulcate, 2 and 3 (VI) each short, subequal in length, 4 (VII) slightly longer than 3, 1–4 each with one pair of basal lateral foveae, foveae of tergite 1 larger than those of 2–4, 5 (VIII) transverse, posterior margin slightly emarginate at middle. Sternite 2 (IV) longest, only with mediobasal foveae, sternites 3 to 5 (V–VII) each short and subequal in length, lacking fovea, 6 (VIII) greatly transverse, posterior margin prominent at middle, 7 (IX) composed of paired membranous structures.

Aedeagus ( Fig. 1D, E ) 0.28 mm long, stout, dorso-ventrally symmetric; median lobe suboval; parameres narrowing at apices, each with one short preapical seta; endophallus armature composed of one median and two elongate lateral sclerites.

Female. Unknown.

Comparative notes. Although there are some pselaphine beetles (e.g., Taiwanophodes minor ; Yin et al. 2012) shared by the Hainan and Taiwan islands, the new species has no closely related congeners from the Taiwanese fauna (19 spp.). Actually, B. diaoluomontis can be readily separated from all East Asian species by the coarsely punctate head and pronotum, combined with the greatly swollen scape that lacks a glandular protuberance, the simple pedicel, as well as the stout aedeagus and the unique shape of its parameres and endophallus armature.

Distribution. South China: Hainan.

Etymology. The new species is named after its type locality, i. e., Diaoluo Mountain.

Figures

FIGURE 1. Habitus and morphological details of Bryaxis diaoluomontis sp. nov., male. A. Dorsal habitus. B. Head and pronotum. C. Scape and pedicel. D, E. Aedeagus, ventral. Scale bars: 0.5 mm in A; 0.2 mm in B; 0.1 mm in C–E.