Platystethus vicinior, 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 : 193-201

12. Platystethus vicinior sp. nov.

( Figs. 28 ; 29; 30; 31A–H; 32M)

Type material examined. Holotype: ♂, CHINA: Xinjiang, Manasi Co. [=Manas Co.], Wangjiacun Village [44.28ºN 86.27ºE], from a grass heap in potato field, 444 m, 2010. VII.3, Y.-C. Li leg. (IZ-CAS). Paratype: 1♂, Xinjiang, valley of Yining River [= Yili River], 540–630 m, 1957. VIII.5, C.-P. Hong leg., Platystethus degener Rey , det. P.M.Hammond, 1980 (IZ-CAS).

Description (holotype). Body ( Fig. 30 A) black to dark brown; mandibles, maxillary palpi, antennae, and legs reddish; elytra with paler pattern in center and posteromedial area. Length [average]: ♂, 2.9 mm.

Male. Head ( Figs. 28 A; 30B) broadest at temples. Disc coriaceous, nearly glabrous, with punctures dense and coarse. Clypeus transverse and protruding beyond anterior border of supra-antennal ridges, with anterior margin shallowly emarginate in middle, furnished a pair of sharp and slender spines. Epistomal suture with middle portion absent, lateral portions short but obvious and posteromedially directed. Supra-antennal ridges elevated. Vertex depressed in anterior part, convex in center; mid-longitudinal suture short, 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. Temple not dilated laterally. Neck not constricted. Occipital suture curved, present only in middle, with large setal fovea and feeble paralateral suture lying behind and at each 1/4 of head width. Mandible stout, incurved at apex.

Pronotum ( Figs. 28 A; 30B) slightly wider than head, widest at near anterior margin, with mid-longitudinal sulcus present whole length, with punctures dense but smaller than in head, surface coriaceous but not microstriate; anterior margin bi-emarginate, anterior lateral angles prominent, no posterior angles; lateral and posterior margins integrated and evenly rounded, without crenulation. Scutellar impression ( Fig. 30 B) bi-reniform in anterior part, anterior margins crescent. Elytra ( Fig. 30 B) with posterior margin truncate, elytral suture dehiscent or partly overlapping.

Abdomen coriaceous. Sternite VII ( Figs. 28 B; 30C) with two reduced teeth on posterior margin, between which not emarginate. Sternite VIII ( Figs. 28 C; 30D) 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 only lateral portions present but short.

Aedeagus ( Figs. 28 D–F; 31A–D) with median lobe slightly inflated at base and gradually narrowed apically; apical orifice fissured to middle of ventral surface, edges of ventral fissure sharply protruding into a pair of long spines which upcurved at apex and constricted at near base; internal sac membranous and rolling into watchspring-shape at base. Paramere arm-like, basal arm with furrow on ventral surface; apical arm explanate and furnished with small seta at apex, another seta at near apical 1/4, and with pits scattered.

Paratype. Body smaller and color lighter. Clypeal spines shorter ( Figs. 29 A; 30E). Abdominal sternites VII–VIII ( Figs. 29 B, C; 30F, G) similar to holotype but smaller. Aedeagal parameres a little asymmetric ( Figs. 29 D–F; 31E–H).

Female. Unknown.

Distribution. China (Xinjiang).

Etymology. The specific epithet is comparative of the Latin adjective “ vicinus ”.

Remarks. The paratype is not completely consistent with the holotype, but we suppose it is an aberrant form or premature adult, because the paratype is much lightly colored both in exocuticle and in aedeagus, and it is located not very far from holotype locality. The new species is allied to P. degener , but different in coloration, sternite VII and aedeagus: the elytral pale pattern is smaller than that in P. degener ; the two teeth on posterior margin of sternite VII are more reduced and farther placed (as in P. alutaceus ); the spines of aedeagal median lobe look obviously different from P. degener or P. alutaceus in lateral view, and the emargination on apex of paramere is larger in the new species (cf. Figs. 31–32 ). Platystethus akkumus Kashcheev is another species alike P. vicinior , but the aedeagal medianlobe of P. akkumus without the two spines as long as that appear on P. vicinior (cf. Fig. 1 (14) in Kashcheev, 1999a: 145). The new species can be distinguished by coloration from P. praetermissus Eppelsheim (cf. Fig. 34 A–B), P. rugifrons Bernhauer , (cf. Fig. 34 F–J), P. rufospinus Hochhuth (cf. Hochhuth, 1851: 51-53 [ P. rufospinus is “mostly black”]), and P. spinicornis Luze (cf. Fig. 34 C–E). Platystethus vicinior can also be separated from the following species: P. depravatus Eppelsheim whose posterior margin of male sternite VII with emargination between teeth (cf. Eppelsheim, 1892: 342); P. spinosus Erichson which with “sutural striae not continued on to the posterior margins of elytra” (cf. Hammond, 1971: 94); P. zaisanicus Kashcheev who has the “vertex tubercles”, which are absent from P. vicinior , and whose posterior margin of sternite VII is emarginated between teeth (cf. Kashcheev, 1999b [1996]: 13–14, Figs. 1–3 ).

Figures

FIGURE 1. Platystethus arenarius (Geoffroy, 1785) 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 = 0.5 mm; F = 0.05 mm; rest, 0.2 mm.

FIGURE 28. Platystethus vicinior sp. nov. I (Holotype): A, head and pronotum ♂ (dorsal view); B, sternite VII ♂; C, sternite VIII ♂; D, aedeagus (ventral view); E, median lobe of aedeagus (lateral view); F, right paramere (in situ) of aedeagus (lateral view). Scales: 0.2 mm.

FIGURE 29. Platystethus vicinior sp. nov. II (Paratype): A, head and pronotum ♂ (dorsal view); B, sternite VII ♂; C, sternite VIII ♂; D, aedeagus (ventral view); E, median lobe of aedeagus (lateral view); F, right paramere (in situ) of aedeagus (lateral view). Scales: 0.2 mm.

FIGURE 30. Platystethus vicinior sp. nov. III (holotype (A – D) and paratype (E – G )): A, habitus ♂ (dorsal view); B, E, forebody ♂ (dorsal view); C, F, sternites VII ♂; D, G, sternite VIII ♂. Scales: A = 1 mm; B, E = 0.3 mm; rest, 0.2 mm.

FIGURE 31. Holotype (A – D) and paratype (E – H) of Platystethus vicinior sp. nov. (aedeagus), and P. alutaceus Thomson, 1861 (I – L) and P. degener Mulsant & Rey, 1878 (M – P) from Britain (aedeagus): A, E, I, M, aedeagus (ventral view); B, F, J, N, aedeagus (dorsal view); C, G, K, O, medianlobe of aedeagus (lateral view); D, H, L, P, right paramere (in situ) of aedeagus (lateral view). Scales: 0.2 mm.

FIGURE 32. Platystethus alutaceus Thomson, 1861 from Britain (A – F), P. de g e n e r Mulsant & Rey, 1878 from Britian (G – L), and P. vicinior sp. nov. (M, paratype): A, G, forebody ♂ (dorsal view); B, H, forebody ♀ (dorsal view); C, I, M, last 3 abdominal segments ♂ (ventral view); D, J, sternite VII ♂; E, K, sternite VIII ♂; F, L, spermatheca. Scales: A, B, G, H = 0.3 mm; F, L = 0.05 mm; rest, 0.2 mm.

FIGURE 34. Platystethus praetermissus Eppelsheim, 1893 (A, B), syntype of P. spinicornis Luze, 1904 (C – E), and syntypes of P. r u gif ron s Bernhauer, 1900 (F – J): A, C, habitus ♂ (dorsal view); B, D, F, forebody ♂ (dorsal view); E, labels of P. spinicornis (syntype in FMNH); G, forebody ♀ (dorsal view); H, sternite VIII ♂ (ventral view); I, J, labels of P. rugifrons (syntypes in SDEI). Scales: A, C = 1 mm; B, D, F, G = 0.5 mm, H = 0.1 mm. [Photos C – E © The Field Museum, FMNHINS 2819581, Photographer Kelsey Keaton, used by permission]