Platystethus fugongensis Lü, 2025

Li, Yang, Ma, Hong-Ye & Lü, Liang, 2025, A new species of Platystethus Mannerheim, 1830 (Coleoptera: Staphylinidae Oxytelinae) from Yunnan, China, Zootaxa 5660 (1), pp. 134-138 : 135

Platystethus fugongensis Lü , sp. nov. [DZÑAḆDzøm]

( Figs 1–2 )

Type material. HOLOTYPE: CHINA: ♂, Y unnan [云南], Nujiang City [怒江], Fugong County [DZḢ县], Shiyueliang Township [石月亮乡] ， 27.25°N, 98.89°E, 2300–2600 m, cow dung, Jun-2024, Bai-Jun Li [李白¥] . PARATYPES: CHINA: ♂, 6♀♀, the same data as holotype .

Description. Body ( Fig. 1A ) black; mandibles, maxillary palpi, reddish brown; antennomeres black; elytra and legs light brown to yellow, darker in margins. Length in average: ♂, 5.4 mm; ♀, 5.9 mm.

Male. Head ( Figs. 1B ) broadest at temples. Disc nearly glabrous, with punctures dense and coarse. Clypeus transverse, with anterior margin moderately emarginate, in middle furnished with short sharp process. Supra-antennal ridges obviously elevated and triangularly horned. Vertex depressed, glabrous, barely punctate in anterior part, convex and with strongly punctate covered at each side of mid-longitudinal suture; mid-longitudinal suture short and deep, posteriorly reaching occipital suture. Eyes slightly convex, shorter than temples, with fine facets; orbital sulcus fine. Temple dilated laterally and lateral margin gradually narrower from the anterior of temple. Occipital suture deep and arciform, with large setal fovea at each end.

Mandible ( Fig. 2A ) stout, and dull and incurved at apex; bearing 3 reduced teeth on inner edge: 2 large with 1 tiny in between; with tiny spur situated in fovea at middle of dorsal surface.

Pronotum ( Fig. 1B ) as wide as head or wider, widest at anterior 3/4, with mid-longitudinal sulcus throughout, with punctures sparser and smaller than in head, without micro-striae; anterior margin bi-emarginate, anterior lateral angles produced, no posterior angles; lateral and posterior margins integrated and evenly rounded. Elytra ( Fig. 1A ) with posterior margin obliquely truncate, elytral suture dehiscent.

Abdomen coriaceous. Sternite VII ( Fig. 2C ) with posterior margin weakly protruding in middle. Sternite VIII ( Fig. 2D ) tri-partitioned by 2 curved narrow sutures, middle part with posterior margin a little curved and with mid-longitudinal internal ridge at anterior 2/3, lateral parts completely separated by middle part, each at mesial side with long process situated with short seta at apex; basal ridge interrupted in middle, sub-basal ridge with middle portion absent. Each anterior margin of tergite IX ( Fig. 2F ) with slender “ventral strut” see Naomi (1989 p. 726, 728).

Aedeagus ( Figs.2G–I )with median lobe bottle-like,inflated at base, sparsely pubescent; internal sac membranous. Paramere arm-like and bent in middle, basal portion with furrow on ventral surface; apical portion furnished with two slender setae: one thinner at apex, one stronger nearing apical 1/3 with fine pits scattered nearby.

Female. Head ( Fig. 1C ) smaller, narrower than pronotum; clypeus longer, slightly protruding in middle of anterior margin which beyond level of supra-antennal ridges; supra-antennal ridges triangularly horned as prominent as in male; vertex slightly convex at side of mid-longitudinal suture; eyes convex, nearly equal to temples in length, temples not dilated. Mandibles ( Fig. 1D ) shorter than in male, with teeth more prominent. Pronotal anterior margin ( Fig. 1D ) with bi-emargination weaker. Abdominal sternite VII with posterior margin straight.

Sternite VIII ( Fig. 2E ) posterior margin broadly rounded and a little protruding in middle. Anterior margin of tergite IX ( Fig. 2F ) without “ventral strut”. Spermatheca ( Fig. 2J ) pedunculately spherical, featuring globoidinflated basal portion and slender, stalky, apex-hooked apical portion.

Distribution. China (Yunnan).

Etymology. The specific epithet is derived from the type locality “Fugong” (= Fugong County).

Remarks. The newly described species closely resembles members of the arenarius -group, such as arenarius , bucerus , and erlangshanus (cf. Figs. 14–15 in Lü & Zhou 2015). They exhibit several shared characteristics: pronounced supra-antennal ridges, a spur on the dorsal aspect of mandibles, a tri-partitioned male sternite VIII with two seta-bearing processes, nearly identical morphology of the aedeagal median lobe, and comparable shape and setation on parameres of aedeagus. Nonetheless, the new species is identifiable by its triangularly horned supra-antennal ridges, which taper linearly, in contrast to bucerus , whose “horns” taper curvilinearly and seem consequently sharper than those of the new species; arenarius and erlangshanus lack horn-like supra-antennal ridges altogether. The position of the sub-apical seta (distance from the parameral apex) on parameres can also be used to distinguish these four species. In addition, P. arenarius possesses an extra seta other than the apical and sub-apical setae (see Figs. 1I & 2K in Lü & Zhou 2015), located in the notch at parameral apex. The notch is also observed in the parameres of bucerus and fugongensis ; however, we did not find seta there.

Figures

FIGURE 1. Habitus (A, C) and head and pronotum (B, D) of Platystethus fugongensis. A, B. Holotype ♂. C, D. Paratype ♀. Scale bars: A, C = 1 mm; B, D = 0.5 mm.

FIGURE 2. Tergites, sternites and Reproductive organs of Platystethus fugongensis. A. right mandible ♂. B. right mandible ♀. C. Sternite VII ♂. D. Sternite VIII ♂. E. Sternite VIII ♀. F. Tergite IX and Tergite X ♂. G. aedeagus (ventral view). H. median lobe of aedeagus (lateral view). I. right paramere of aedeagus (lateral view). J. spermatheca. Scale bars: A-I = 0.2 mm; J = 0.05 mm.