Oxytelus acriculiclypeatus, a New Species of Oxytelus Gravenhorst, 1802 (Coleoptera: Staphylinidae: Oxytelinae) from Borneo Author Lü, Liang 0000-0001-7533-6244 Hebei Collaborative Innovation Center for Eco-Environment, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei Province 050024, China. lianges.luex@gmail.com text Zootaxa 2024 2024-02-23 5415 4 593 597 http://dx.doi.org/10.11646/zootaxa.5415.4.9 journal article 10.11646/zootaxa.5415.4.9 1175-5326 10695722 DFD45E44-A4BA-4F42-B859-3C1F35BF4695 Oxytelus acriculiclypeatus sp. nov. ( Figs. 1–2 ) Type material. Holotype : ♁, MALAYSIA , Borneo Sabah , Danum Valley , 4°58′N 117°47′E , Flight Intercept Trap , June 1999 // BMNH (E), 2005-177, H. Mendel // Oxytelus acriculiclypeatus ♁ HOLOTYPE det. LÜ Liang, 2024 ( BMNH ) . Paratypes : 2♁♁, Borneo Sabah , Danum Valley , 4°58′N 117°47′E , Flight Intercept Trap , June 1999 // BMNH (E), 2005-177, H. Mendel // Oxytelus acriculiclypeatus ♁ PARATYPE det. LÜ Liang, 2024 ( BMNH ). Description. Body ( Fig. 1 ) medium-sized, glossy, dark brown to blackish. First two antennomeres, maxillary palpi, and legs yellowish brown and elytra brown and vaguely translucent. Body length about 4.5 mm . Male . Head ( Figs. 1 & 2A ) sub-pentagonal, widest at eyes or temples (accurately at temples). Disc bearing scarce setae and covered with large punctures. Clypeus elongated triangularly, protruding beyond anterior margin of supra-antennal ridges, as long as 1/4–1/3 head length, slightly depressed in central part, surface glabrous and occasionally and slightly coriaceous; anterior margin narrow and pointed in middle. Epistomal suture with lateral portions lightly incurved and running posteriorly to level of anterior margin of eyes. Vertex slightly convex but flat and feebly coriaceous near clypeus, posterior part limited ( holotype ) or not ( paratypes ) in median portion; midlongitudinal suture indistinct ( holotype ) or missing ( paratypes ); paralateral sutures vague. Eyes with fine facets, convex, and shorter than temples. Temples slightly rugose, posterolaterally dilated. Occipital suture with middle portion distinct (in holotype ), punctately connected (in one paratype ), or completely missing (in the other paratype ); nuchal ridge interrupted in middle, dorsobasal ridge present. TABLE 1. Measurements (in millimeters) of the types of Oxytelus acriculiclypeatus .

Holotype	Paratype 1	Paratype 2
Body length	4.594	4.307	4.452
Forebody length	2.183	2.140	2.337
Head length	0.625	0.800	0.862
Head width	0.849	0.824	0.871
Eye length	0.232	0.222	0.234
Temple length	0.294	0.294	0.318
Supra-antennal ridge vertex distance	0.482	0.449	0.480
Neck width	0.498	0.490	0.510
Pronotum length	0.824	0.627	0.633
Pronotum width	0.809	0.862	0.896
Elytra length	0.766	0.755	0.782
Left elytra width	0.538	0.528	0.534
Right elytra width	0.508	NA	0.555
Abdomen width	1.050	1.093	1.128

Mandible stout, falciform, strongly incurved; apex sharply pointed. Antenna ( type II) as long as or slightly longer than head and pronotum together, with apical antennomere slightly shorter than two preceding together, antennomeres 4–11 with basal dish ( Fig. 1A–C ). Pronotum ( Figs. 1D–F , 2A ) transverse, broadest at near anterior 1/4, as wide as head or slightly broader. Disc 3-sulcate, median sulcus and two curved paramedial sulci deep and punctate, two paralateral depressions punctate; lateral margin even in front and indistinctly crenulate behind, posterolateral angles rounded. Elytra ( Fig. 1D–F ) punctate and sparsely pubescent, but not rugose, without lateral longitudinal ridge. Abdomen barely coriaceous and sparsely pubescent, broadest at segment VI. Sternite VII ( Fig. 2B ) with posterior margin straight and with densely haired patch in middle. Sternite VIII ( Fig. 2C ) with subbasal ridge continuous and straight; posterior margin shallowly and narrowly bi-emarginate near middle; central plate short, broadly and shortly protruding in middle, with apical margin weakly emarginate and carinate. Aedeagus ( Fig. 2D–H ). Median lobe elongate and slightly broader basally, ventral edge of apical orifice with two pointed processes near middle, with sclerite-like or membranous structures in apical part of median lobe; apico-medial hook with apical tip pointed and downcurved and with transverse carina behind tip, basal process short; dorsal membranous area covering most of apical part of dorsum and nearly across length of median lobe. Parameres arm-like, with apex flattened, a little broadened and rounded, with ridge on ventral and lateral surface of each piece and screw-tracked at elbow bend, at near 1/2 of apical arm situated with long seta. FIGURE 1. Habitus ( A–C ) and forebody ( D–F ) of the types of O. acriculiclypeatus sp. nov. A , D : holotype; B , E : paratype 1; C , F : paratype 2. Scale bars: A–C = 1 mm, D–F = 0.5 mm. FIGURE 2. Holotype of O. acriculiclypeatus sp. nov. A : head and pronotum in dorsal view; B : sternite VII in ventral view; C : sternite VIII in ventral view; D : aedeagus in ventral view; E : aedeagus in dorsal view; F : median lobe of aedeagus in lateral view; G : right paramere of aedeagus in lateral view; H : line-drawing showing details of apical orifice and apico-medial hook of median lobe in ventral view. Scale bars: A = 0.5 mm, B–H = 0.2 mm. Female . Unknown. Distribution ( type locality). Malaysia (Borneo: Sabah ). Etymology. The specific epithet is derived from two Latin adjectives acriculus and clypeatus , referring to the sharp clypeal tip. Remarks. This species closely resembles O. megaceros and was found in overlapping areas ( Lü & Zhou 2015 ). However, it can be distinguished from the latter by several male morphological features (cf. Fig. 11 in Lü & Zhou 2012, Fig. 34 in 2015): the anterior clypeal margin with a sharper tip than that of O. megaceros , the posterior margin of sternite VIII with a broader central plate and a carina lying across the whole width of the posterior margin of central plate, the sharper and more slender processes on the apical orifice, and the apico-medial hook with a smaller apical tip but without the connecting scape that attaches it to the body of aedeagal median lobe.