New species and new combinations of Asian Batrisodes Reitter (Coleoptera, Staphylinidae, Pselaphinae), and synonymy of Batrisodellus Jeannel with Batrisodes

Continuing surveys on the pselaphine fauna in China have revealed four undescribed species of the genus Batrisodes: Batrisodes angustelytratus sp. n. (with Pachycondyla ant) and B. longwangshanus sp. n. from Zhejiang, B. bamian sp. n. (with Pseudolasius ant) from Hunan, and B. songxiaobini sp. n. (with Formica ant) from Yunnan. The genus Batrisodellus is placed as a junior synonym of Batrisodes, syn. n.; this taxonomic act results in eight new combinations: Batrisodes cerberus, B. coprea, B. cristatus, B. fengtingae, B. laticollis, B. longulus, B. palpalis, and B. punctipennis. The Russian Far East species Basitrodes cornutus is transferred to Batrisodes, comb. n.


Introduction
The fauna of the largely Holarctic genus Batrisodes Reitter in China is poorly explored.Currently only four species of this genus have been known: two from the mainland and two from Taiwan.Three of them, B. masatakai Nomura, B. babaianus Nomura, and B. simplex Yin & Li, are placed in the subgenus Excavodes Park (Nomura 2007, Yin andLi 2013), and one, B. pruinosus (Reitter), in the nominotypical subgenus (Besuchet 1981).Recent surveys on the pselaphine beetles in eastern, central, and southwestern China in 2013 and 2014 have revealed four undescribed Batrisodes species that are described herein.Of them, three were collected from colonies of the ant genera Pachycondyla Smith, Pseudolasius Emery, and Formica Linnaeus.Due to the weak concept of subgenera applied for the eastern Asian Batrisodes, the subgeneric system is not used in this paper.After an examination of the newly collected material, as well as types, photos, and the original descriptions of the described species, we found that all characters used to define Batrisodellus Jeannel to be weak.Since Batrisodellus cannot be clearly separated from Batrisodes, it is placed in synonymy with the latter.In addition, Basitrodes cornutus Kurbatov is transferred to Batrisodes based on the characters extracted from its original description and figures, and a photo of an identified male.

Material and methods
The type material of the new species is housed in the Insect Collection of Shanghai Normal University, Shanghai, China (SNUC).
The collecting data of the material are quoted verbatim.A slash is used to separate different labels.Authors' supplementary notes are included in square brackets.Each type specimen bears the following label: 'HOLO-TYPE [red] (or PARATYPE [yellow]), ♂ (or ♀), Batrisodes + specific name sp. n., det.Yin & Shen, 2015, SNUC'. Morphological terminology follows Chandler (2001), except our use of 'ventrite' instead of 'sternite' when describing meso-and metathoracic structures.
The following abbreviations are applied: AL-length of the abdomen along the midline; AW-maximum width of the abdomen; EL-length of the elytra along the sutural line; EW-maximum width of the elytra; HLlength of the head from the anterior clypeal margin to the occipital constriction; HW-width of the head across eyes; PL-length of the pronotum along the midline; PW-maximum width of the pronotum.Length of the body is a combination of HL + PL + EL + AL.Description.Male (Fig. 1A).Body reddish brown, BL 2.12-2.18mm.Head about as long as wide, HL 0.48-0.49mm, HW 0.47-0.49mm; with large vertexal foveae; frons flat, lacking modification, concave between moderately raised antennal tubercles; clypeus coarsely punctate, with round anterior margin; lateral vertexal carinae faintly present from frons to anterior margins of vertexal foveae, median vertexal carina distinct, extending from level of posterior margins of vertexal foveae to base; each eye composed of about 45 facets, lacking ocular canthi; postgenal area with many long erect setae visible in dorsal view.Antennal club (Fig. 2A) formed by apical three antennomeres, IX and X strongly transverse, unmodified, XI large, with distinct, apically-truncate basal denticle.Pronotum about as long as wide, PL 0.48-0.47mm, PW 0.47-0.46mm; disc slightly convex; median and lateral longitudinal sulci distinct; lacking median antebasal fovea; with small antebasal tubercles.Elytra much wider than long, EL 0.60-0.63mm, EW 0.74-0.76mm; base distinctly constricted; each elytron with three large nude basal foveae; lacking discal striae; marginal striae complete.Mesofemora (Fig. 2B) with thin but distinct ventral spine near middle, mesotibiae (Fig. 2C) with triangular preapical spur; metatibiae (Fig. 2D) with long apical tuft of setae.AL 0.56-0.59mm, AW 0.79-0.81mm; abdominal tergite IV (first visible tergite) with strongly oblique marginal carinae; discal carinae short.Length of aedeagus (Fig. 2E-G) 0.44 mm, median lobe broadened in dorso-ventral view, split at apex.Female.Unknown.

Differential diagnosis.
The new species is most similar to Batrisodes fengtingae (Yin & Nomura) [previously placed in Batrisodellus, transferred to Batrisodes due to the synonymy of these two genera, see below] by sharing similar modification on antennomeres XI and spines on the legs, and an asymmetric aedeagus.Batrisodes angustelytratus can be readily separated from B. fengtingae and all other congeners by the strongly constricted elytral base, as well as the unique form of aedeagus.
Biology.Adults were collected from a colony of a Pachycondyla ant nesting under a rock.
Differential diagnosis.Batrisodes longwangshanus can be separated from all other congeners by a combination of the simple antennal club, the presence of the ocular canthi, the dentate mesotrochanter, mesofemora, and mesotibiae, and the unique form of the aedeagus.
Biology.All adults were collected from leaf litter samples in a mixed forest.
Female.Unknown.Differential diagnosis.The protruding anterior margin of the frons is shared in a number of Asian species, e.g.Batrisodes cornutus (Kurbatov) (transferred from the genus Basitrodes, see below), and Batrisodes acutifrons Jeannel.But the characteristic forms of the antennomeres VII-XI and protruding frons in the male, as well as the aedeagal structure readily separate this new species from all other congeners.
Biology.Adults were collected from a colony of a Formica ant nesting under a rock.
Etymology.The species epithet recognizes the collecting efforts of Xiao-Bin Song, who collected the type series and many other interesting pselaphines.

New synonymy and new combinations
René Jeannel (Jeannel 1958) in his treatment of Japanese Pselaphinae created a number of new genera placed near Batrisodes, e.g.Basitrodes Jeannel, Petaloscapus Jeannel, Batrisodellus, Kigatrodes Jeannel, and Speobatrisodes Jeannel.All of these taxa were defined based on weak characters which are either variable in a genus, or merely male sexual features, e.g. the form of the aedeagus, and the modification of male antennomeres.In our opinion their diagnoses and relationships to Batrisodes must be revised in the future.
According to the original description (Kurbatov 1984), the Russian Far East species Basitrodes cornutus Kurbatov lacks the unique aedeagal form of Basitrodes, but shares many characters typical of Batrisodes.After an examination of a high-resolution photo of an identified male [collecting data: Kunashir Is., cordon Alekhinskij, rotten Abies, 31.VII.2011,Kurbatov leg.], this species is here moved to Batrisodes comb.n.
Etymology.The new name is dedicated to Zhong Peng, who collected most specimens of the type series of this species.