Platystethus subnitens, Lü, Liang & Zhou, Hong-Zhang, 2015

Lü, Liang & Zhou, Hong-Zhang, 2015, Review of the Genus Platystethus Mannerheim (Coleoptera: Staphylinidae: Oxytelinae) in China, Zootaxa 3915 (2), pp. 151-205 : 188-190

10. Platystethus subnitens sp. nov.

( Figs. 23 & 24 )

Type material examined. Holotype: ♂, CHINA: Xinjiang, Kelamayi [=Karamay, 45.59ºN 84.87ºE], in cotton field, 2008. VI.22, H. He leg. (IZ-CAS). Paratypes: 4♂♂, 7♀♀, same data as holotype; 1♂, Ku’erle [= Koria or Korla or Kurla, 41.73ºN 86.17ºE], 2008. VI.1, H. He leg. (IZ-CAS).

Description. Body light brown; maxillary palpi, antennae, elytra and legs lighter; forebody dorsal surface coriaceous or micro-striate. Small in size, length [average]: ♂, 2.9 mm; ♀, 3.3 mm.

Male. Head ( Figs. 23 A; 24A) broadest at temples. Disc nearly glabrous, punctate. Clypeus transverse, surface coriaceous and scarcely punctate, protruding beyond anterior border of supra-antennal ridges, with anterior margin shallowly emarginate in middle, furnished a pair of slim spines. Epistomal suture with middle portion absent, lateral portions posteromedially directed. Supra-antennal ridges elevated. Vertex depressed in anterior part, slightly convex in center; mid-longitudinal suture fine, posteriorly reaching occipital suture. Eyes slightly convex, shorter than temples, with fine facets; orbital sulcus feeble. Long and deep longitudinal groove sculptured throughout mesial side of eye and temple, continuous with coriaceous area at mesial side. Temple not dilated laterally. Neck not constricted. Occipital suture slightly curved, present only in middle, with large setal fovea at each end. Mandible ( Fig. 24 C) stout and incurved; bearing 3 teeth on inner edge: front one obvious, other two tiny.

Pronotum ( Figs. 23 A; 24A) equal to head or slightly narrower, widest at near anterior 1/4, with midlongitudinal sulcus present whole length, with punctures as dense as but sparser than in head, with micro-striae present; anterior margin slightly bi-emarginate, anterior lateral angles prominent, no posterior angles; lateral and posterior margins integrated and evenly rounded, not crenulate. Scutellar impression bi-reniform in anterior part. Elytra with posterior margin truncate, elytral suture dehiscent or partly overlapping.

Abdominal sternite VII ( Figs. 23 C; 24E) with posterior margin slightly and gradually protruding in middle.

Sternite VIII ( Figs. 23 D; 24F) tri-partitioned by 2 curved narrow sutures, middle part truncate on posterior margin, without mid-longitudinal internal ridge, lateral parts separated by middle part but touched at anterior margin, each with two teeth at mesial side of posterior margin: one sharp, one dull; basal ridge interrupted in middle and subbasal ridge with middle portion absent.

Aedeagus ( Figs. 23 G–I; 24I –M) with median lobe inflated at base and gradually narrowed apically; apical orifice fissured to middle of ventral surface, edges of ventral fissure protruding into a pair of long spines with tips connected; internal sac membranous and rolling into watch-spring-shape at base. Paramere arm-like, hugging apical part of median lobe; basal arm with furrow on ventral surface; apical arm narrowed at apex and slightly explanate at near apex of dorsal edge, furnished with one seta at apex and one at near apex of ventral edge.

Female. Head and pronotum ( Figs. 23 B; 24B) smaller; clypeus more protruding, anterior margin truncate without denticles; mid-longitudinal suture shorter; coriaceous area beside groove smaller. Mandibles ( Fig. 24 D) shorter than male, with teeth more prominent. Posterior margin of sternite VII straight. Sternite VIII ( Figs. 23 E; 24G) not partitioned, without teeth, with posterior margin gradually narrowed in middle.

Spermatheca ( Figs. 23 F; 24H) comma-formed, basal part inflated into globoid, apical part thin and sharp, shorter and curved.

Distribution. China (Xinjiang).

Etymology. The new species is similar to P. nit ens , so the specific epithet is derived from the name of P. nitens .

Remarks. Similar to P. nitens , P. r ug i f ron s, and P. capito , but males of the first two species both have three grooves (each side) at the medial side of eyes, where P. capito and P. subnitens have only one, P. subnitens has a rough sculptured patch beside the groove. Platystethus rugifrons and P. capito have no spines on the clypeus, while P. nitens and P. subnitens do. The males of P. subnitens can be distinguished from those of P. depravatus by the absence of teeth or emargination on the posterior margin of sternite VII (cf. Eppelsheim 1892: 342).

Figures

FIGURE 23. Platystethus subnitens sp. nov. I: A, head and pronotum ♂ (dorsal view); B, head and pronotum ♀ (dorsal view); C, sternite VII ♂; D, sternite VIII ♂; E, sternite VIII ♀; F, spermatheca; G, aedeagus (ventral view); H, median lobe of aedeagus (lateral view); I, right paramere (in situ) of aedeagus (lateral view). Scales: A, B = 0.3 mm; F = 0.05 mm; rest, 0.2 mm.

FIGURE 24. Platystethus subnitens sp. nov. II: A, head and pronotum ♂ (dorsal view); B, head and pronotum ♀ (dorsal view); C, right mandible ♂; D, right mandible ♀; E, sternite VII ♂; F, sternite VIII ♂; G, sternite VIII ♀; H, spermatheca; I, aedeagus (ventral view); J, median lobe of aedeagus (ventral view); K, median lobe of aedeagus (dorsal view); L, median lobe of aedeagus (lateral view); M, right paramere (in situ) of aedeagus (lateral view). Scales: H = 0.05 mm; rest, 0.2 mm.