A remarkable new Awas Löbl from southern China (Coleoptera, Staphylinidae, Pselaphinae)

Abstract A new distinctive species of the rare Oriental goniacerine genus Awas Löbl, Awas gigas sp. n., is described and illustrated, based on three males and fourteen females taken at the Daoyao Shan Natural Reserve in the southern Chinese province of Guangxi. All specimens were collected from colonies of the ant genus Pachycondyla F. Smith nesting in decomposing woods.


Introduction
The genus Awas Löbl currently contains six described species scattered throughout the Malay Peninsula, Taiwan, and continental China (Löbl 1994;Nomura 1995;Nomura and Idris 2004;Yin, Li and Zhao 2010;Yin and Li 2012). After a discussion of the morphological details and a phylogenetic analysis of the genus, Löbl (1994) placed Awas in the goniacerine tribe Arnylliini, as a sister taxon of Harmophorus Motschulsky. Members of Awas are unique in having a conspicuously elongate postocular region of the head, and a relatively small, basally strongly constricted abdomen in contrast to the large body.
All Awas species are rare in scientific collections, known from one (A. giraffa Löbl, A. sinicus Yin & Li, A. kayan Yin & Li, A. loebli Yin & Li), four (A. rajah Nomura & Idris), and five (A. shunichii Nomura) specimens (additional records for A. rajah and A. shunichii provided in Sugaya and Nomura 2003;Nomura and Idris 2005). Information of the habitat of the known species are largely limited due to the inadequate number of specimens: A. giraffa, A. shunichii, A. sinicus, and A. kayan were collected from leaf litter, and A. rajah and A. loebli were taken by flight intercept traps.
In July 2014, our team collected two males and two females of an additional species from a colony of a Pachycondyla ant at the Dayao Shan Natural Reserve in the southern Chinese province of Guangxi. With the knowledge of the host ant, a second survey in the same locality was conducted in May 2015, and another thirteen specimens (one male, twelve females) were found in several colonies of the same ant species. Based on the above material, a new species is formally described, and compared to the known congeners. This species is distinct in having the largest body size of more than 5.0 mm.

Material and methods
All material treated in this paper is housed in the Insect Collection of Shanghai Normal University (SNUC), Shanghai, China.
The following abbreviations are applied: ALlength of the abdomen along the midline; AnLlength of the antenna; AWmaximum width of the abdomen; ELlength of the elytra along the sutural line; EWmaximum width of the elytra; HLlength of the head from the anterior clypeal margin to the occipital constriction; HWwidth of the head across eyes; PLlength of the pronotum along the midline; PWmaximum width of the pronotum. Length of the body is a combination of HL, PL, EL, and AL. Diagnosis. Body large-sized, length 4.79-5.12 mm; head with a greatly elongate postocular region; pronotum relatively stout, basolateral margins moderately incised at level of antebasal sulcus, lacking distinct setal tufts; elytra lacking basal fovea. Female has a relatively larger abdomen than male.
Comparative notes. At first glance Awas gigas is very distinct from other species in the genus by possessing a large body size. It shares with A. giraffa and A. rajah the lack of two pairs of setose tufts on the basolateral margins of the pronotum, and lack of a distinct basal elytral fovea, but can be separated from both by the relatively stouter pronotum. Awas kayan also lacks distinct pronotal setose tufts, but has each elytron possessing a well-defined basal fovea, and the elytra are broader at basal third.
Biology. All individuals of Awas gigas were collected from colonies of a Pachycondyla ant nesting inside or under decomposing woods in broad-leaved forests (Fig. 3).
Distribution. Southern China: Guangxi. Etymology. The specific epithet indicates the large body size of the new species.