Contributions to the knowledge of the genus Horaeomorphus Schaufuss (Coleoptera, Staphylinidae, Scydmaeninae) in mainland China

Abstract Five new species of the ant-like stone beetle genus Horaeomorphus Schaufuss (Scydmaeninae: Glandulariini) from China are described: Horaeomorphus hainanicus sp. n., Horaeomorphus biwenxuani sp. n., Horaeomorphus pengzhongi sp. n., Horaeomorphus hujiayaoi sp. n. and Horaeomorphus punctatus sp. n. The previously unknown male of Horaeomorphus chinensis Franz, 1985 is now discovered, and its aedeagus and metatrochanter are illustrated. The latter species is newly recorded from Zhejiang. Three females from Guangxi are also recorded, but their identity remains unconfirmed until associated males become available. A key to Horaeomorphus of mainland China is included.

Among asian glandulariine (= former Cyrtoscydmini, see Newton 2015) genera, Horaeomorphus is characterized by the mesoventral intercoxal process being shorter and less elevated than the mesocoxae, the metaventral intercoxal process with two long spines projecting posteriorly, the presence of a small pit at the posteromesal margin of each supra-antennal tubercle, pronotal base with distinct median pit in addition to lateral pits, and each elytron with two foveae connected by a U-shaped groove extending anteriorly; many species have the male trochanters modified (Jałoszyński 2015).
Recent examination of unsorted material in our collection revealed five new species of Horaeomorphus from Hainan, Guangxi, Yunnan and Xizang. Moreover, during our recent expedition, two males of H. chinensis Franz, 1985 were discovered in the type locality, Fujian: Guadun (=Kuatun), which makes it possible to add a description of male characters. This species is also newly recorded from Zhejiang: Baishanzu. Three females from Guangxi are recorded; they belong to a group of species characterized by a strongly convex and broad body, but their identities remain unknown until associated males become available. A key to Horaeomorphus of mainland China is included.

Material and methods
All material treated in this study is housed in the Insect Collection of Shanghai Normal University, Shanghai, China (SNUC).
The collecting data are quoted verbatim. Each type specimen bears the following label: 'HOLOTYPE [red] (or PARATYPE [yellow]), ♂ (or ♀), Horaeomorphus + specific name sp. n., det. Zhou & Zhang, 2016, SNUC'. The following abbreviations are applied: AeL-length of the median lobe of aedeagus in ventral view; AnL-length of the antennae; BL-length of the body (= HL + PL + EL); EI-elytral index (= EL / EW); EL-length of the elytra along the suture, from the base of scutellum to the apex; EW-maximum width of the elytra; HW-width of the head across eyes; HL-length of the head from the anterior clypeal margin to the occipital constriction; PL-length of the pronotum along the midline; PWb-width of the pronotum at base; PWm-maximum width of the pronotum; SpL-length of the spermatheca. (China: Yunnan), all of them have elongate and convex habitus, the pronotum with three pits connected by a groove, the base of elytra barely wider than the basal margin of pronotum and protruded, recurved metatrochanters in males. Among these species, H. hainanicus sp. n. and H. pengzhongi sp. n. have a similar shape of the aedeagus, structures of endophallus and slender parameres each with two subapical setae, as those in H. chinensis. The character combination of the pronotum and elytra with a dense and distinct punctation, the recurved metatrochanters without expansions on their ventral margins in male, the parameres longer than median lobe and the structures of the endophallus can be used to distinguish H. chinensis from the two species mentioned above.

Bionomics.
Specimens from Guadun were collected by sifting material from an ant nest (Fig. 10B) in a relatively dry rotten trunk in a bamboo forest; four specimens from Baishanzu were collected from under bark of a rotten tree.  Fig. 6F) elongate, SpL 0.13mm; with longitudinal groove at middle. Comments. These females have strongly convex and broadened elytra (EI 1.30-1.38), distance between humeral calli wider than the width of the pronotum at base, large and deep punctures sharply delimited from background in the center of pronotal disc and anterior third of elytra. The shape of the spermatheca is similar to that of H. caverniventris Jałoszyński, 2006 (Malaysia: Pahang), but females of the Malaysian species are larger (2.79-3.12 mm). Therefore the three specimens almost certainly belong to a new species, but a male must be found for formal description.

Horaeomorphus
Distribution. Southern China: Guangxi. Diagnosis. Horaeomorphus hainanicus can be readily separated from all other congeners by its moderately large (2.53-3.08 mm) and elongate body, fine punctation on pronotal disc and elytra, rounded apices of metatrochanters in male, parameres each with 3-5 apical setae and two subapical setae, unique structure of endophallus and shape of spermatheca.
Bionomics. Specimens of the type series were collected from ant and termite nest material in rotten wood and under bark of standing rotten logs in rainforests of Hainan.
Distribution. Southern China: Hainan. Etymology. The specific epithet refers to the province where the type locality of the new species lies. Diagnosis. Horaeomorphus punctatus can be readily separated from all other congeners by its moderately large (2.07-2.36 mm) and stout body, broad pronotum with a row of three pits connected by a shallow, barely notable groove; dense and coarse punctation on elytra, unmodified metatrochanters in male, aedeagal parameres lacking setae at apices and shape of spermatheca.
Distribution. Southern China: Yunnan. Etymology. The specific epithet refers to the coarse punctation of the elytra.  Diagnosis. Horaeomorphus pengzhongi can be readily separated from all other congeners by its moderately large (3.00 mm) and elongate body, sparse and fine punctation on pronotal disc and elytra, protruded metatrochanter with expansion on its ventral edge in male, parameres each with four apical setae and two subapical setae and unique structures of endophallus.
Female. Unknown. Comments. Horaeomorphus pengzhongi is similar to many congeners (see comments of H. chinensis); the relatively larger body (3.00 mm), elongated metatrochanters each with the ventral expansion in male, each paramere with two subapical setae and structures of endophallus are clearly different and can be used to identify this new species.
Etymology. This species is dedicated to Zhong Peng, one of the collectors of the type specimen. Diagnosis. Horaeomorphus biwenxuani can be readily separated from all other congeners by its moderately large (2.78 mm) and elongate body, small pronotum lacking basal groove, with a row of three dorsal pits, subtriangular metatrochanter with distal edge produced into a short acute spine, and slender aedeagus with a complicated and strongly asymmetrical endophallus.

Female. Unknown.
Comments. This new species with remarkably long legs has subtriangular metatrochanters in males, each with a sharp distal edge. This unique character can be found also in all four known Nepalese congeners: H. obrus Vít, 2004, H. deharvengi Vít, 2004, H. himalayensis Franz, 1974and H. nepalensis Franz, 1973(Franz 1974Vít 2004), but so far has not been recorded in Horaeomorphus outside the Himalayas. However, a relatively small body (2.78 mm; among Himalayan species only H. deharvengi can be smaller than 3mm) and strongly asymmetrical endophallus are clearly different from characters of the Nepalese species. An asymmetrical endophallus also occurrs in H. deformatus Jałoszyński, 2006   Diagnosis. Horaeomorphus hujiayaoi can be readily separated from all other congeners by its moderately large (2.53 mm), short pronotum with five basal pits connected by a shallow groove, unmodified metatrochanters, median lobe of aedeagus with a blade-shaped, asymmetrical apex bent at an obtuse angle in relation to the long axis of aedeagus and asymmetrical parameres each with ten apical and subapical setae.
Comments. This new species has the aedeagal median lobe with an apical bladeshaped projection bent to the left in ventral view and parameres of unequal lengths, characters shared with H. obrus Vít, 2004 (Nepal: Janakpur, Bagmati). Horaeomorphus hujiayaoi can be unambiguously separated from its Nepalese congener by the much smaller body (2.53 mm vs 4.3 mm in H. obrus) and different structures of the endophallus.
Distribution. Southern China: Guangxi. Etymology. This species is dedicated to Jia-Yao Hu, who collected the type specimen.