Taxonomic study on Lathrobium Gravenhorst (Coleoptera, Staphylinidae, Paederinae) from Longwangshan Mountain, East China

Abstract Species of the genus Lathrobium Gravenhorst from Longwangshan Mountain, Zhejiang, East China are studied. A total of five species are recognized, among which three are described here as new: Lathrobium lingae sp. n., Lathrobium longwangshanense sp. n. and Lathrobium uncum sp. n., one species was unidentified and the female of Lathrobium tianmushanense Watanabe is newly reported. All of these species are illustrated and keyed.


Introduction
To the present, a total of 625 species of the genus Lathrobium Gravenhorst have been known worldwide, 64 of them from China (Löbl and Smetana 2004 and subsequent papers). Longwangshan Mountain (at. 30°24'N,119°27'E) in the south of the Anji County forms the Tianmushan mountain range and Mt. West Tianmushan stand 9.5 kilometers apart. Only two species of Lathrobium have been recorded by  from West Tianmushan Mountain, but no members of the genus have been reported yet from Longwangshan Mountain, Zhejiang Province, East China.
In recent years, we made several collecting trips to the Longwangshan Mountain, and obtained a lot of Lathrobium specimens. On the basis of the examination, four species were recognized and one species was unidentified, among which three were revealed to be new, and the female of L. tianmushanense Watanabe was newly discovered. The purpose of this paper is to describe and illustrate the Lathrobium species of Longwangshan Mountain, and to provide an identification key to Lathrobium species of Longwangshan Mountain and West Tianmushan Mountain.

Material and methods
All specimens were collected from the leaf litter of the forest floor by sifting. They were killed with ethylacetate and then dried. Dissections were done in water. The genital organs and other dissected parts were mounted in Euparal (Chroma Gesellschaft Schmidt, Koengen, Germany) on plastic slides that were placed on the same pin as the specimen. Photos were taken by a Canon EOS 40D Camera with an MP-E 65 mm Macro Lens or by a Canon G9 Camera mounted on an Olympus CX31 microscope. The type specimens are deposited in the Insect Collection of Shanghai Normal University (SNUC).
The following abbreviations are used in the text, with all measurements in millimeters:

BL
length of the body from the labral anterior margin to the anal end HL length of the head from the clypeal anterior margin to the head base HW maximum width of the head PL length of the pronotum along the midline PW maximum width of the pronotum EL length of the elytra from the apex of the scutellum to the elytral posterior margin  1A). Body brown with paler apex, legs reddish brown, antennae reddish brown to yellowish brown.
Elytra at suture distinctly shorter than pronotum; wider than long; punctation well-defined; and hind wings completely reduced.
Abdomen with dense pubescence; sternite VII ( Etymology. The species is named after Rui-Fen Ling, who collected the type specimens.

Remarks.
The new species is close to L. fengae in similar general form. Lathrobium lingae differs especially by the male sternite VII with deeper impression, male sternite VIII with regularly triangular apico-median emargination, and aedeagus with gracile Etymology. The species is named after its type locality.

Remarks.
The new species is similar in most respects to L. tianmushanense, but it differs in having relatively stout body, HL/PL being more than 0.80, male sternite VI with tufted pubescence at concavity and aedeagus with longer twisted dorsal sclerites. In L. tianmushanense, the body is relatively slender, HL/PL is more than 0.73, the male sternite VI has the concavity lacking pubescence and the dorsal sclerites of the aedeagus are much shorter. Slightly smaller than male; posterior margin of tergite VIII (Fig. 5G) weakly asymmetrical; sternite VIII ( Fig. 5H) distinctly pointed in the middle; tergite IX ( Fig. 5I) (not separated from X) with long and acute lateral processes; tergite X ( Fig. 5I)  Habitus as in Fig. 2A. Externally similar to L. lingae, except for the lighter average coloration, the somewhat smaller body size and the sparser punctation on the head and the pronotum.
Distribution. East China (Zhejiang: Longwangshan Mountain). Etymology. The specific name 'uncum' (Latin adjective) means 'hooked'. Remarks. The new species and L. tamurai from Zhejiang share many features, particularly the general form. They can be readily distinguished by the male sternite VII lacking an impression and with several modified discal setae, male sternite VIII with two rows of modified setae in large but faint apical impression and another row along the posterior margin, and slender aedeagus with the ventral process being hook-shaped in L. uncum, whereas in L. tamurai, the male sternite VII has the impression evenly covered with modified setae on each side of the median part; the male sternite VIII has a horseshoe-shaped impression with dense modified setae; and the robust aedeagus has a straight ventral process.  Habitus as in Fig. 2B. Externally similar to L. lingae, except for the somewhat smaller body size and the more oblong pronotum.

Distribution. East China (Zhejiang: Longwangshan Mountain).
Remarks. The species resembles L. rougemonti Watanabe from Zhejiang by sharing the similar form, male sternite VII with weak impression and male sternite VIII with many dark setae in the large impression, but that of aedeagus typically with two closer dorsal sclerites. In L. rougemonti, aedeagus have two widely separated dorsal sclerites. The original description of L. rougemonti is based on the holotype from West Tianmushan Mountain. The type was not examined, but based on the description and the illustration (habitus, male abdominal apex and aedeagus) provided by , there is still doubt whether the population from Longwangshan represents a new species. As intermediate form exists, it will be necessary to study the type material of L. rougemonti for clarification. (Assing pers. comm.) A key to the Lathrobium species from Longwang -West Tianmu Mountains  Male sternite VII (Fig. 3A) with deep apico-median impression; male sternite VIII ( Fig. 3C)