A NEW SPECIES OF THE GENUS Leptobium Casey (COLEOPTERA: STAPHYLINIDAE: PAEDERINAE) FROM CENTRAL NORTHERN ANATOLIA, AND A DISTRIBUTIONAL CHECKLIST TO TURKISH SPECIES

: In this study, a new species of the genus Leptobium Casey, Leptobium orgeli sp. n. (Çorum province) from central northern Anatolia in Türkiye is described, illustrated, and distinguished from congeners. A total of 21 species is currently known from Türkiye. A distributional checklist of Leptobium of Türkiye is provided. Distributions of the endemic Leptobium species in central northern Anatolia are mapped. In addition, new and additional distribution data for 10 species of Leptobium are reported from different countries of the Palearctic Region. The material examined was based on specimens collected between 1927 and 2021, and contained additional specimens in European museums and Alaşehir Zoological Museum.


Introduction
The genus Leptobium Casey, 1905 (Coleoptera: Staphylinidae: Paederinae) is represented by 74 species and two subspecies in the Palaearctic region (Schülke & Smetana 2015, Assing 2017, Anlaş & Örgel 2020).According to Assing (2005), the complete distribution of Leptobium includes the south of the Palaearctic region from the Canary Islands to the Russian Far East, with Leptobium gracile (Gravenhorst, 1802) reaching into the northeast of the Ethiopian region.But the vast majority of species of the genus are distributed in the Mediterranean region and the Middle East, with the highest species diversity in Türkiye, where 20 species have been recorded so far (Anlaş & Örgel 2020), corresponding approximately one quarter of the known species in the Palaearctic region.
Leptobium species can be found in almost any habitat providing optimal humidity and water supplies.They mostly can be collected in unforested habitats such as meadows and pastures, as well as in forest, on flowers and lakeshores, usually at lower to intermediate elevations (Assing 2005, Anlaş 2012).According to Assing (2005), little is known about the phenology and biology of Leptobium species.According to Assing (2005), adults can be seen throughout the year, but they are much more common in spring.Also, teneral specimens of some species can be found both in spring and in late autumn.According to the published data on the genus and to personal observations, species of the genus are most probably predators of other invertebrates.
Most species of Leptobium are difficult to identify by external characters.A reliable identification at species level is possible only based on an examination of male sexual characters.

Materials and Methods
The material of the study was obtained from the specimens collected from Algeria, Croatia, Greece, Russia, Tunusia and Türkiye between 1927 and 2021.The specimens collected from Türkiye were sampled using aspirator and sifter methods.The material was examined under a Stemi 508 microscope (Zeiss Germany).All photographs were obtained using a digital camera (Zeiss Axiocam 208).All photographs were edited with Helicon Focus v. 6, and Corel Draw v. X7.A distribution map of the endemic Leptobium species in central northern Anatolia was prepared using the Google Earth Pro (2021) software.Nomenclature of the terminalia and the style of the description of Leptobium orgeli sp.n. follows Assing (2005).
Body length was measured from the anterior margin of the mandibles to the abdominal apex, head length was measured from the anterior margin of the clypeus to the neck, the length of pronotum was measured along the median line, the length of elytra from the apex of the scutellum to the posterior margin of the elytra (at the suture), and the length of the aedeagus from the apex of the ventral process to the base of the bulbus.
Abbreviations used to indicate collections where the studied material is deposited are as follows: AZMM-Alaşehir Zoological Museum, Manisa Celal Bayar University, Türkiye (S.Anlaş) .

Taxonomy
Family Description: Habitus as in Fig. 1a.Body 7.9-8.5 mm long.Colouration: head, pronotum, and abdominal segments III-VI black; elytra and abdominal segments VIII-X rufous, segment VII distinctly bicoloured with broad posterior margin rufous; antennae reddish and legs yellowish brown.
Head slightly oblong, approximately 1.05-1.10times as long as wide (Figs 1a-b); integument without microreticulation; eyes approximately half as long as postocular region in dorsal view, weakly projecting from lateral outline of head; puncturation coarse and sparse, irregularly spaced, slightly denser and smaller in lateral than that in central dorsal area interstices wider than diameter of punctures both in lateral and median dorsal area; pubescence black and sparse.Antennae 1.82-1.98mm long; antennomere III distinctly longer than II, approximately 1.5-1.6 times as long as II, antennomeres IV-VI longer than the width, antennomeres VII-X about as wide as long; antennomere XI almost twice as long as wide.
Pronotum oblong, approximately 1.2 times as long as wide and as wide as head (Figs 1a-b), slightly narrowed posteriorly, with subparallel lateral margins in dorsal view; dorsal surface without pronounced impressions; punctation similar to that of head, but slightly denser; microsculpture absent; pubescence blackish and sparse.
Elytra slightly wider than pronotum, approximately 1.05-1.10times as wide as pronotum (Figs 1a-b) and shorter than pronotum, at suture about 0.75-0.80times as long as pronotum; punctation not granulose, smaller, well-defined and denser than that of pronotum and head; microsculpture absent; pubescence reddish, slightly more distinct than that of head and pronotum.Hind wings reduced.Tarsi relatively long (Fig. 1a).
Abdomen slightly wider than elytra, approximately 1.05 times as wide as elytra (Fig. 1a), widest at segment VI; puncturation moderately dense and well-defined; all tergites with distinct microsculpture, composed of dense and fine transverse meshes and striae; pubescence blackish and sparse; posterior margin of tergite VII without palisade fringe.depressed in posterior median area (Fig. 1c); sternite VIII with posterior incision not reaching middle of the sternite, little more than 1/3 the length of the sternite (Fig. 1d); aedeagus approximately 1.5-1.6 mm long (Figs 1e-f), dorsal plate of aedeagus long and slender, apically acute; the shape of the ventral process oblong and asymmetrical and on the right elongated in ventral view.

Comparative notes:
The new species can be distinguished from other congeners (Leptobium angoranum Anlaş & Örgel, 2020;L. ilgazicum Assing, 2010;L. ponticum Assing, 2005;L. yagmuri Anlaş, 2017) in central northern Anatolia by the completely different morphology of the aedeagus and by the larger body (L. angoranum: 4.7-5.1 mm; L. ilgazicum: 6.6-7.0 mm; L. ponticum: 6.0-7.3 mm; L. yagmuri: 5.1-6.3 mm).External characters of the new species are similar to L. illyricum (Erichson, 1840), thus a reliable separation of the two species is possible only based on an examination of the aedeagus, especially the differently shaped ventral process.The species can be distinguished from L. illyricum by the more slender and pointed ventral process in ventral view.

S. Anlaş
Etymology: The species is dedicated to Semih Örgel, Manisa, who collected some of the type specimens of the new species.
Distribution and bionomics: The species was found at four localities from Çorum (Osmancık, Danişment) (Fig. 2, Table 1).The type specimens were collected under stones in various grassland areas at altitudes of 1400-1490 m.

Discussion
The main center of diversity of the genus Leptobium is in the Mediterranean countries and adjacent regions, especially Türkiye.21 species of the genus have been recorded so far from Türkiye, where only five species were known before 2005 (Table 1).Despite the fact that the Turkish fauna of the genus has been well-studied in recent years, it seems most likely that the diversity of Leptobium species in Türkiye is far greater than presently known.Because, many species remain to be discovered and described.The main reason for the situation is that some regions of Türkiye (e. g. northeastern, eastern and southeastern Anatolia) have not been sufficiently studied in terms of Leptobium fauna yet.
The most distinctive specialty of the Leptobium fauna of Türkiye is the high rate of endemism.In Türkiye, 17 of 21 species are endemic and the endemism rate represent more than 80% of the Turkish Leptobium fauna.Restricted distribution ranges and the strong link to specific geological substrates are important characteristics of the endemic fauna of Türkiye (Çıplak et al. 1992(Çıplak et al. , Demirsoy 2007).Endemic species in Türkiye are distributed in southern Anatolia (seven species), northern and central northern Anatolia (five species), western Anatolia (four species) and Thrace Region (one species).It is thought that both the number of species and endemic species will increase in the future, with further detailed studies on the Leptobium fauna of Türkiye.
Anlaş research project.During the field trips in Çorum province, a new Leptobium species has been discovered.The number of currently known Leptobium species, including the newly described species, in Türkiye is 21, among which 17 are endemic to the country.New and additional distribution data for nine species of the genus are reported from different countries of the Palearctic Region.
This study is mainly based on field studies in central northern Anatolia carried out within the scope of a S24 S.