A new species of Peucoglyphus Bernhauer from New Guinea (Coleoptera, Staphylinidae, Staphylininae)

Abstract Peucoglyphus ken sp. n., a new species from New Guinea is described. Adding the new species, this rare Wallacean genus from the tribe Staphylinini (subtribe Philonthina) currently includes five species. An updated identification key for the genus is provided.


Introduction
Peucoglyphus Bernhauer, 1926 is a genus of the rove beetle tribe Staphylinini (subtribe Philonthina) that was enacted for P. corporaali Bernhauer, 1926, a species from Buru Island in Indonesia (Bernhauer 1926). Since then nothing at all had been published about Peucoglyphus for almost a century until Schillhammer (2011) added three more species: P. solomonicus Schillhammer, 2011 from Solomon Islands, P. celebensis Schillhammer, 2011 from the island of Sulawesi (Indonesia), and P. balkei Schillhammer, 2011 from Irian Jaya. The abovementioned paper also provided an updated diagnosis and notes on the phylogenetic affinities of that rare genus. It immediately allowed me to identify a puzzling specimen from New Guinea that I had on loan from the Netherlands Centre for Biodiversity (Naturalis) in Leiden, as a new species of Peucoglyphus. Here I provide the description of this new species along with some comparative notes, and accordingly update the identification key to species of Peucoglyphus of Schillhammer (2011).

Material and methods
The holotype of the new species is kept at the Netherlands Centre for Biodiversity (Naturalis) at Leiden (NCBN, M.E. Gassó Miracle and A. van Assen). All photographs illustrating the description were taken by Ken Puliafico (Copenhagen) with a Leica DFC 420 camera attached to a Leica MZ16A microscope with the help of Leica Application Suite (Leica Microsystems, 2003-2007 and Automontage Pro (Synoptics Ltd, 1997-2004. Peucoglyphus ken sp. n. urn:lsid:zoobank.org:act:DCA914C6-A2E4-4EC1-9E89-7EFBAFD31FBD http://species-id.net/wiki/Peucoglyphus_ken Description.15.5 mm long (measured from apex of opened mandibles to apex of abdomen). Habitus: Figs 1, 2. Black and shiny, head and pronotum with deep dark blue metallic glance, elytra brilliant glossy, with strong metallic blue glance, scutellum brilliant, but darker, with violet glance; mouthparts dark brown to black; legs black, except femora at base dark brown; apex of abdomen beginning from segment VIII reddish-brown.
Head large, with rounded posterior angles, only slightly wider than long (head length from base of labrum to neck 2.5 mm; maximal head width, at eyes 2.7 mm); tempora 1.8 times as long as eyes, eyes posteriorly shifted dorsad; surface of head smooth with micropunctation faint and sparse at disk, but coarser and denser at tempora; frons with one pair of large setiferous punctures, each located near anterior part of internal margin of eye; other large, possibly setiferous punctures arranged in irregular groups behind eye and along posterior margin of head; tempora with one large setiferous puncture located closer to posterior margin of head than to posterior margin of eye; bilobed labrum with semi-membranous yellowish extension developed along its entire apical margin (Fig. 3). Pronotum slightly transverse (length along midline 2.5 mm, maximal width 2.8 mm), with parallel lateral sides, broadly rounded posterior angles and distinct anterior angles; at sides slightly sinuate in front of base and just posterior to anterior angles; micropunctation as on disk of head: very sparse and faint; large possibly setiferous punctures are grouped at anterior corners, 2-3 on disk on each side and some along posterior margin. Elytra wider and longer than pronotum (elytral length from base to apical margin 3.5 mm, maximal elytral width 3.7 mm), their surface with faint and sparse micropunctation and dense microsculpture, slightly longitudinally wrinkled at base and along apical margin; each elytron laterally without carina; scutellum faintly punctate. Metaventrite without conspicuous fold posterolaterally (illustrated in Schillhammer 2011 for P. balkei in fig. 4). Abdomen: first five visible tergites (III-VII) medially more or less smooth, impunctate, but laterally and basally with more or less coarse punctuation; all tergites with only one basal carina, tergites IV-VI with more or less deep transversal impression; male sternite VIII with medio-apical emargination; male sternite IX with short slightly asymmetrical poorly sclerotised basal portion, and with slightly bilobed apex.
Aedeagus in parameral view ( Fig. 4) with median lobe having massive apical portion that is as wide as basal bulb, in lateral view (Fig. 5) slightly curved, with very short paramere consisting of two symmetrical lobes.
Bionomics and distribution. Known from the type locality only. No data about the collecting method or bionomics of the holotype is available.
Etymology. With pleasure I dedicate the new species to Kenneth (Ken) Puliafico, currently a digitalization assistant at the Department of Entomology at the Natural History Museum of Denmark. Ken's excellent work as a specimen photographer and database specialist, aiming to digitize thousands of Coleoptera types kept in our collection, is a notable contribution towards the better infrastructure for beetle systematics. The species name "ken" is a noun in apposition.
Comparison. Based on the rather small eyes that are shorter than tempora (Fig.  1), the dark legs (Figs 1 and 2), and the distinct nuchal constriction (Fig. 1), P. ken can be placed near P. solomonicus Schillhammer, 2011, at least diagnostically. However, P. ken differs from P. solomonicus in proportions of the forebody (cf . Fig 1 and fig. 2 in Schillhammer 2011), in the color of the apex of the abdomen which is reddish brown, in lacking an arcuate row of large setiferous punctures extending from infraorbital area on to tempora, and in the structure of the abdominal tergites having only one basal carina (contrary to two carinae in P. solomonicus). Also, from all other congeners with known males P. ken strikingly differs in the shape of the aedeagus (cf. Remarks. The new species matches the generic diagnosis of Peucoglyphus provided in Schillhammer (2011) in all characters except lacking temporal carina (formed by confluent punctural grooves) and except slightly different configuration of the semi-membranous extension of labrum. Temporal carina is present in all other species of the genus, and the semi-membranous extension of labrum is developed along the entire width of labral lobes in P. ken (Fig. 3), but laterally reduced in all other species of the genus. However, the structure of the aedeagus in P. ken is remarkably different from all other species of Peucoglyphus with known males. Unlike P. corporaali, P. balkei and P. solomonicus, the aedeagus of P. ken has a distinct but strongly reduced paramere, and enlarged (in dorsal or ventral view, Fig. 4) apical portion of the median lobe without the subapical tooth so characteristic for other species of Peucoglyphus (cf. Fig. 5 and figs 10-12 in Schillhammer 2011). The shape of the paramere in P. ken suggests that in other species of the genus it is even stronger reduced, rather than fused to the median lobe, the condition earlier not clearly understood (Schillhammer 2011). Since the antennae and labial palps are largely missing in the holotype of P. ken, the corresponding structures cannot be compared with other congeners. Noteworthy, that the laterally reduced semi-membranous extension of the labrum is among the characters that distinguish Peucoglyphus from the closely related genera of Philonthina: Leucitus Fauvel, 1878, Actinus Fauvel, 1878and Mysolius Fauvel, 1878, all having such extension fully developed. The fully developed semi-membranous extension of labrum in P. ken shared with them, and the structure of its aedeagus that is also rather similar to some species in those genera, confirm the affinities of Peucoglyphus noted in Schillhammer (2011).