A review of the genus Xotidium Löbl , 1992 ( Coleoptera , Staphylinidae , Scaphidiinae ) , with descriptions of five new species

In the present study, we have reviewed all species of the genus Xotidium Löbl, 1992, as well as five new species from Borneo, Malaysia, and Sulawesi, Indonesia, namely, Xotidium flagellum sp. n., X. heissi sp. n., X. meridionale sp. n., X. smetanai sp. n., X. tarantulatum sp. n. A key to all Xotidium species is provided. The female genitalic characters of Xotidium are illustrated and described for the first time.


Introduction
The genus Xotidium Löbl, 1992, currently comprises seven species from the subtropical and tropical regions of Mauritius, Sri Lanka, the Himalayas, the Lesser Sunda Islands, the Philippines, and Eastern Australia. Members of this genus have narrow body with approximate mesocoxae and metacoxae. They appear to be related to the members of Scaphoxium Löbl, 1979 and Toxidium Le-Conte, 1860, belonging to the Toxidium group because of the shared approximate mesocoxae and metacoxae. However, this genus was included in the Baeocera group by Leschen and Löbl (2005) based on seven synapomorphies. Xotidium can be readily distinguished from Scaphoxium and Toxidium by the presence of multidentate mandibles, two-segmented labial palpi, pronotum with anterior bead, and the presence of secondary lines of mesoventrite. They may be collected from fungi growing up rotten woods and accumulated litter on the forest floor, based on collection data and personal observation. They are also usually found in the higher altitudes of forested areas. However, their feeding habits and natural history still remain unknown. Xotidium is distributed exclusively in the subtropical and tropical parts of Palaeotropical region, excluding Neotropical region, parts of Indonesia Islands to Australia, and the continental Africa. Some unidentified samples collected from Borneo, Malaysia, which have been preserved at Muséum d'histoire naturelle, Genève, Switzerland, and new samples, which were collected in Sulawesi, Indonesia by the first author, are described below as new species, and new information about their distribution is provided. In addition, female genitalia have been observed to be useful in the scaphidiines for defining a group of species or specific species (Ogawa and Sakai 2011;Ogawa and Löbl 2013). However, such characterization needs further investigation.
In the present study, we have reviewed all the members of Xotidium and describe five new species collected from Borneo, Malaysia, and Sulawesi, Indonesia, and present the first reported observations of the female genitalia in Xotidium. Moreover, we provide a key to all Xotidium species, including these new species.

Material and methods
The examined samples were collected by the first author and procured from the collections deposited at the Natural History Museum, London, United Kingdom (NHM) and the Muséum d'histoire naturelle, Genève, Switzerland (MNHG). We have referred to a study by Ogawa and Löbl (2013) and the references quoted therein for methods and terminology. The photographs of the habitus in dorsal and lateral views were captured using a single-lens reflex camera (Canon® Eos Kiss X7) with a macro photo lens (Canon® MP-E 65mm Macro lens) attached to a stand (LPL® CSC-10), and then the focus-stack images were created using COMBINE ZM. A stereomicroscope and biological microscope with a single-lens reflex camera (described above) were used for illustrations. Measurements of the body length and width and of the antennae were taken using an ocular micrometer under the stereomicroscope, but antennomere I was not measured. Some of the illustrations of the lateral habitus are mirror-reversed because of the symmetrical ventral structure. The label data are given verbatim.
Head with eye width almost the same as interocular distance. Punctuation sparse and fine.
Pronotum wider than long. Punctuation sparse and fine, as on head. Scutellum with exposed apex.
Elytra as long as wide, widest at basal fourth, lateral margins sharply narrowed apically, minutely serrate at inner part of posterior margin. Punctuation fine and sparse as on pronotum. Sutural striae extending outwards along basal margin to form basal striae, reaching humeral area and joined with lateral striae.
Hypomeron and lateral portion of mesoventrite smooth. Lateral portion of metaventrite finely and sparsely punctate. Metanepisternum about four times as long as wide, without longitudinal line. Mesepimeron almost as long as wide. Metacoxa about six times as wide as metacoxal process. Ventrite I sparsely and finely punctate.
Protarsomere V about three times as long as each I-IV. Mesotarsomere I about three times as long as each II-IV; V about 2.5 times as long as each II-IV. Metatarsomere I about twice as long as each II and III; each II and III about 1.5 times as long as IV; V about twice as long as IV.
Protarsomeres I-III possibly with tenent setae, but invisible at ×80 magnification, not enlarged. Aedeagus about 0.52 mm long; parameres symmetrical, with moderately widened apical section much longer than third of total parameral length; internal sac with a sinuate and curved flagellum, widened basally and apically (Fig. 8d).
Remarks. This species is very similar to X. pygmaeum (Löbl) in the smaller body, but may be easily distinguished by the very long flagellar sclerite of male genitalia. Etymology. This species epithet is named in honour of the collector of the holotype, E. Heiss from Innsbruck, Austria.  (Löbl); b X. mauritianum (Vinson); c, d X. notatum (Löbl). a (left), c Holotype; a (right), paratype. Scale: 1 mm. Description (male). Dorsal and ventral surface almost reddish-brown (Fig. 5a). Antennae almost yellowish-brown, but antennomeres VI-XI blackish. Legs reddish-brown to brown; tarsi paler than tibiae and femora. Head, pronotum, and elytra sparsely and finely pubescent.

Xotidium heissi
Head with eye width almost the same as interocular distance. Punctuation sparse and fine.
Pronotum wider than long. Punctuation sparse and fine, as on head. Scutellum almost as long as wide, with exposed apex.
Elytra almost as long as wide, widest at basal fourth, lateral margins sharply narrowed apically, minutely serrate at inner part of posterior margin. Punctuation fine and sparse as on pronotum. Sutural striae extending outwards along basal margin to form basal striae, reaching humeral area and joined with lateral striae.
Hypomeron and lateral portion of mesoventrite smooth. Lateral portion of metaventrite finely and sparsely punctate. Metanepisternum about four times as long as wide, without longitudinal line. Metepimeron almost as long as wide. Metacoxa about six times as wide as metacoxal process. Ventrite I sparsely and finely punctate.
Protarsomere V about 2.5 times as long as each I-IV. Mesotarsomere I about 2.5 times as long as each II-IV; V about twice as long as IV. Metatarsomere I about three times as long as each II-IV; V about 1.5 times as long as each II-IV.
Protarsomeres I-III possibly with tenent setae, but invisible at ×80 magnification, not enlarged. Aedeagus 0.54 mm long; parameres symmetrical, with strongly widened apical section longer than third of total parameral length; internal sac with a sinuate flagellar sclerite, basally widened and bent (Fig. 8a).
Head with eye width almost the same as interocular distance. Punctuation sparse and fine.
Pronotum wider than long. Punctuation sparse and fine, as on head. Scutellum with slightly exposed apex.
Elytra longer than wide, widest at basal sixth, lateral margins sharply narrowed apically, minutely serrate at inner part of posterior margin. Punctuation fine and sparse as on pronotum. Sutural striae interrupted at basal third.
Hypomeron and lateral portion of mesoventrite smooth. Lateral portion of metaventrite finely and sparsely punctate. Metanepisternum about four times as long as wide, without longitudinal line. Mesepimeron concealed. Metacoxa about six times as wide as metacoxal process. Ventrite I sparsely and finely punctate.
Protarsomere V about three times as long as each I-IV. Mesotarsomere I about twice as long as each II and III; V about twice as long as IV. Metatarsomere I about 2.5 times as long as each II and III; V about three times as long as IV.
Protarsomeres I-III possibly with tenent setae, but invisible at ×80 magnification, not enlarged. Aedeagus 0.54 mm long; parameres symmetrical, with moderately widened apical section shorter than third of total parameral length; internal sac with a sinuate and very long flagellum (longer than aedeagus), basally widened and bent (Fig. 8f).
Female Distribution. Indonesia: southern Sulawesi. Remarks. This species is similar to X. smetanai sp. n. in lacking sutural striae and X. tubuliferum Löbl in the long sclerite as flagellum of male genitalia, but it is easily distinguished from them by the body color and the widened apical section of parameres. Etymology. This species epithet is in honour of the collector of its holotype, A. Smetana, Ottawa Canada.
Head with eye width almost the same as interocular distance. Punctuation sparse and fine.
Pronotum wider than long. Punctuation sparse and fine, as on head. Scutellum with slightly exposed apex.
Elytra longer than wide, widest at basal sixth, lateral margins sharply narrowed apically, minutely serrate at inner part of posterior margin. Punctuation fine and sparse as on pronotum. Sutural striae interrupted at basal third.
Hypomeron and lateral portion of mesoventrite smooth. Lateral portion of metaventrite finely and sparsely punctate. Metanepisternum about four times as long as wide, without longitudinal line. Mesepimeron almost as long as wide. Metacoxa about six times as wide as metacoxal process. Ventrite I sparsely and finely punctate.
Protarsomere V 2.5 times as long as each I-IV. Mesotarsomere I about twice as long as II; II 1.2 times as long as each III and IV; V 1.5 times as long as each III and IV. Metatarsomere I about three times as long as each II and III; each II and III 1.1 times as long as IV; V about twice as long as IV.
Protarsomeres I-III possibly with tenent setae, but invisible at ×80 magnification, not enlarged. Aedeagus about 0.5 mm long; parameres symmetrical, with moderately widened apical section slightly longer than third of total parameral length; internal sac with straight, evenly wide flagellar sclerite (Fig. 8b).
Etymology. The species epithet is derived from Mapala Tarantula, the climbing club of Gorontalo State University.
Head with eye width almost the same as interocular distance. Punctuation sparse and fine.
Pronotum slightly wider than long, with an anterior bead. Punctuation sparse and fine, as on head. Scutellum almost as long as wide, with exposed apex.
Elytra almost as long as wide, widest at basal sixth, lateral margins sharply narrowed apically, minutely serrate at inner part of posterior margin. Punctuation fine and sparse as on pronotum. Sutural striae extending outwards along basal margin to form basal striae, reaching humeral area and joined with lateral striae.
Hypomeron and lateral portion of mesoventrite smooth. Lateral portion of metaventrite finely and sparsely punctate. Metanepisternum about four times as long as wide, without longitudinal line. Mesepimeron almost as long as wide. Metacoxa about six times as wide as metacoxal process. Ventrite I sparsely and finely punctate, with microsculpture.
Protarsomere I twice as long as each II-IV; V 2.5 times as long as each II-IV. Mesotarsomere I 2.5 times as long as II; II 1.2 times as long as each III and IV; V 2.5 times as long as each III and IV. Metatarsomere I about three times as long as each II and III; each II and III 1.1 times as long as IV; V about twice as long as IV.
Male. Protarsomeres I-III possibly with tenent setae, but invisible at ×80 magnification, not enlarged. Aedeagus about 0.44 mm long; parameres symmetrical, with weakly widened apical section as long as fourth of total parameral length; internal sac with a sclerite as flagellum, straight, evenly wide, sometimes bent at base.
Measurements ( Distribution. Indonesia: northern Sulawesi. Remarks. This species is similar to X. bolmarum Löbl from Lombok in its color and body size, but may be easily distinguished by the straight and more elongate sclerite in the internal sac.