Lethrus (Lethrus) schneideri sp. n. (Coleoptera, Geotrupidae) from Greece

Abstract Lethrus (Lethrus) schneideri Král & Hillert, sp. n. from Thrace, Greece, is described. The new species is morphologically most similar and probably closely related to Lethrus (Lethrus) apterus (Laxmann, 1770) and Lethrus (Lethrus) ares Král, Rejsek & Schneider, 2001. Diagnostic characters (shape of mandibles, ventral mandible processes, pronotum and parameres) are illustrated. Character matrix for separation of males of the Lethrus species closely related to Lethrus schneideri Král & Hillert, sp. n. and geographic ranges for all species studied are mapped.


Introduction
The genus Lethrus Scopoli, 1777, is a Palaearctic geotrupid genus that has a wide distribution range and occurs from central and south-eastern Europe, including the Balkan Peninsula and western part of Turkey in the west, to Mongolia and the Ninxia province of China in the south-east (cf. e.g., Král and Nikolajev 2006, Král et al. 2001, Nikolajev 2003, Král and Hillert 2013. About 120 species are currently known, all flightless and with coalescent elytra. Most of them exhibit strictly allopatric distribution ranges restricted commonly to relatively small areas (cf. e.g., Hillert 2013, Nikolajev 2003). So far, investigations of this genus in the Balkan Peninsula are relatively scanty. The first three species, L. (L.) elephas, L. (L.) raymondi and L. (L.) schaumii, have been described by Reitter as late as 1890. The next species, L. (L.) fallax, has been discovered and described 85 years later by Nikolajev in 1975. Recently, based on systematic investigations by the present authors and by the Italian coleopterist Riccardo Pittino, five additional species have been recognized and described: L. (L.) ares Král, Rejsek & Schneider, 2001;L. (L.) liviae Pittino, 2011 and L. (L.) halkidikiensis Král & Hillert, 2013;L. (L.) perun Král & Hillert, 2013 and L. (L.) strymonensis Král & Hillert, 2013. Lethrus specimens collected from the Balkan Peninsula were also studied in parallel by standard molecular analysis methods and results obtained indicate significant differences between populations meriting for at least several of them having the "species status" (Drožová et al. in prep.).
A new and morphologically clearly different species was found in the material obtained mostly by the present authors during their expeditions to Greece between 2009 and 2012. The species was named Lethrus (Lethrus) schneideri and described below.

Material and methods
The following abbreviations identify the collections housing the material examined (curators are given in parentheses). Genitalia of three males of the new species were dissected for examination. The material was examined with an Olympus SZ61 stereo microscope; measurements were taken with an ocular grid. Photographs were taken using a Canon 550D digital camera equipped with a Canon MP-E 65/2.8 MACRO lens with 5:1 optical magnification. Final images were composed from multiple partially focused images using Zerene Stacker (Zerene Systems LLC, Richland, WA, USA). Specimens of the presently described species are provided with one red printed label: "Lethrus (Lethrus) schneideri sp. nov., HOLOTYPUS, ALLOTYPUS or PARATYPUS, David Král & Oliver Hillert det. 2013". The exact label data are cited for the material; individual lines of each label are separated by a single slash (/), [p] -preceding data within quotation marks are printed. The authors' remarks and additional comments are enclosed in brackets.
The nomenclature used to describe morphological structures is that proposed by Pittino (2011) and Král and Hillert (2013). Additional material examined. 6 specimens). Greece: Description of holotype. Maximally developed male with well developed ventral mandible processes (Figs 4C, F; 5C). Total body length 29 mm. Oblong, strongly convex; dorsal surface black, moderately shiny, except almost alutaceous pronotum; ventral surface black with fine blue tinge, moderately shiny, claws black-brown; macrosetation black.
Mandibles symmetrical, external outline almost semicircular, pointed subapically in dorsal aspect (Figs 1C, 4C) with maximum width approximately at middle of mandibles length.
Ventral mandible processes (Figs 1F, 2C, 4F, 5C) weakly asymmetrical, right process slightly more developed than left one and with different angle in lateral aspect. Both processes distinctly longer than length of mandible; base thickened, not exceeding lateral mandibular outline in dorsal aspect, with slightly concave external outline in basal half in frontal aspect; longitudinal keel on base laterally present, straight and distinctly subparallel to lateral mandibular outline, approximately as broad as maximum width of mandibles outline basally; in lateral aspect weakly arcuate, approximately subparallel to lateral mandibular outline, slightly divergent gradually basad approximately from middle of its length. Inferiobasal tooth absent; both processes bent inward approximately in middle of mandibles length in frontal view; anterior subapical tooth absent; apical emargination absent; apical tooth round.  Pronotum (Figs 2F; 4C, F; 5C) transverse, distinctly broader than base of elytra, broadest just behind middle; margin entirely bordered, slightly crenulate in anterior parts. Anterior angles weakly but distinctly projecting anterolaterad, with angulate outline; lateral margin approximately weakly emarginate anteriorly, then straight to round posterior angle; basal margin straight. Punctation of dorsal surface simple, consisting of deep, sparsely and irregularly distributed punctures; punctures separated by approximately two to four their diameters discally, surface near lateral margins considerably shagreened and alutaceous. Scutellar shield widely triangular, finely shagreened. Elytra almost semicircular, apices not prominent, each apex forming independent arc. Epipleuron strongly narrowed apicad, epipleural keel not reaching elytral apex. Whole surface alutaceous, finely transversally rugose; striae not indicated, entirely vanishing in rugosities.
Legs. Profemur not armed, protibia with row of eight gradually proximad diminishing external denticles, and with row of tubercles on ventromedial edge.
Aedeagus as in Fig. 3C. Variability in males. Body length 19-30 mm. Mandible processes in medium developed and underdeveloped (hypothelic) males short, more or less straight with simply rounded to almost acute apically.
Differential diagnosis. Among the species distributed in the Balkan Peninsula, the new species is most similar and probably closely related to Lethrus (L.) ares Král, Rejsek & Schneider, 2001 (Table 1). Additionally, L. (L.) schneideri sp. n. is probably an endemic species of the southernmost slopes of the Rhodope Mountains approximately between the towns of Xánthi and Komotiní, while L. (L.) ares is known so far only from four spots all situated in the Eridropótamos river basin (Fig. 7) and L. (L.) apterus is a widely distributed Pannonian species known from Burgenland (Austria), Moravia (Czech Republic) and Serbia in the west to the Don river basin in the east (Fig. 6). The geographic range of the latter is separated from that of the new species by the Thracian lowlands in Bulgaria inhabited by L. (L.) schaumii, and by the Rhodope Mountains.  straight and distinctly subparallel to lateral mandibular outline, approximately as broad as maximum width of mandibles outline basally (Fig. 1B) straight and distinctly subparallel to lateral mandibular outline, approximately as broad as maximum width of mandibles outline basally (Fig. 1C) lateral longitudinal keel on base of ventral mandible process in lateral aspect weakly arcuate, approximately parallel to lateral mandibular outline, divergent gradually basad approximately from middle of its length ( shape of ventral mandible process in frontal aspect external outline concave basally, inferiobasal tooth present, round; subapical tooth distinct, apical emargination present, remarkably deep (Fig. 1D) external outline strongly concave basally, inferiobasal tooth present, round; subapical tooth distinct, apical emargination present, shallow (Fig. 1E) external outline concave basally, inferiobasal tooth absent; subapical tooth absent, apical emargination absent (Fig. 1F) shape of anterior pronotal angle projected anterolaterad, angulate ( restricted only to south-easternmost foothills of the Rhodope Mts (Eridropótamos river basin region in Greece) (Fig. 7) restricted only to southernmost foothills of the Rhodope Mts (Komotiní and Xánthi regions in Greece) (Fig. 7) Collecting circumstances. The type series was collected from uncultivated fields on moderately steep, approximately SE oriented slope consisting of loess soil (Figs 8A-B) in a millitary area.
Name derivation. Patronymic, named in honour of our longtime friend, entomologist Jan Schneider (Praha, Czech Republic), an excellent Geotrupidae and Silphidae specialist.