Raquel López-Antoñanzas
email: raquel.lopez-antonanzas@umontpellier.fr

Pablo Peláez-Campomanes

Jérôme Prieto

Fabien Knoll

NEW SPECIES OF KARYDOMYS (RODENTIA) FROM THE MIOCENE OF CHIOS ISLAND (GREECE) AND PHYLOGENETIC RELATIONSHIPS OF THIS RARE DEMOCRICETODONTINE GENUS

Keywords: Mammalia, Cricetidae, <i>Karydomys</i>, taxonomy, Miocene, cladistics, Chios Mammalia, Cricetidae, Karydomys, phylogenycladistics, taxonomy, Miocene, Chios

Karydomys is a rare and little diversified democricetodontine, of which only six species are currently recognised. This group of rodents is first recorded known sincein the Early Miocene (MN3) in China and spread quickly after to Kazakhstan and Greece (MN 4). Karydomys reached south-western and central Europe by early Middle Miocene times (MN5), where it became extinct shortly thereafter (MN6). New findings from the Miocene of Chios Island (north-eastern Aegean Sea) reveal the presence of a new species of Karydomys in the Keramia Formation. KarydomysK. strati sp. nov. is characterized by the presence of a labial spur on the anterolophule, the lack of anterior protolophule on the M1 and by the presence of a double metalophule on the M2. A cladistics analysis involving all the species of Karydomys and some closely related species of Democricetodon and Cricetodon has been carried out. The results show that Karydomys split early into two different lineages, an "eastern stock", which that includes the central Asian (KarydomysK. debruijni and KarydomysK. dzerzhinskii) and Greek (KarydomysK. symeonidisi, KarydomysK. boskosi and KarydomysK. strati sp. nov.) species, and a "western lineage", which is constituted by the western and central European species (KarydomysK. wigharti and KarydomysK. zapfei). The evolutionary stage of Karydomys strati sp. nov suggests that the lowermost part of the Keramia Formation, usually attributed to the Middle Miocene, is older than previously thought.

INTRODUCTION

Asia Minor has been an important area for the exchange of faunas between Europe, Asia and Africa, especially during the early Early Miocene (RoglRögl, 1999;[START_REF] Koufos | Neogene/Quaternary mammalian migrations in Eastern Mediterranean[END_REF]. At that time, important dispersals from the East occurred through that area, deeply transforming the mammalian composition of Europe (Van der [START_REF] Made | Intercontinental relationship Europe-Africa and the Indian Subcontinent[END_REF][START_REF] Agustí | A calibrated mammal scale for the Neogene of Western Europe. State of the art[END_REF]. The faunal changes were particularly important for rodents, since the entrance of "modern" cricetids in Europe at the end of the Early Miocene disrupted the structure of communities at the endo of the Early Miocene, which, had been till then, were dominated by eomyids and glirids until then [START_REF] Daams | Paleoenvironmental and paleoclimatic interpretation of micromammal faunal successions in the upper Oligocene and Miocene of north central Spain[END_REF][START_REF] Van Der | Evolution of Early--Middle Miocene rodent faunas in relation to long-term palaeoenvironmental changes[END_REF][START_REF] Agustí | A calibrated mammal scale for the Neogene of Western Europe. State of the art[END_REF].

The entrance appearance of cricetids in Europe was, nevertheless, not the result of an isolated single dispersal event migration but instead occurred in a succession of eventsseveral successive waves, as shown by the timing of arrival of the three main groups of cricetids, the Democricetodontinae, Megacricetodontinae and Cricetodontinae [START_REF] Bruijn | Report of the RCMNS working group on fossil mammals, Reisenburg 1990[END_REF][START_REF] Theocharopoulos | Late Oligocene--Middle Miocene Democricetodon, Spanocricetodon and Karydomys n. gen. from the Eastern Mediterranean area[END_REF]; [START_REF] Van Den Hoek | Aliveri revisited, a biogeographical appraisal of the early Miocene mammals from the eastern Mediterranean[END_REF][START_REF] Oliver | Early Miocene evolution of the rodent Megacricetodon in Europe and its palaeobiogeographical implications[END_REF]. In order to fully understand all thesesuch faunal migrationsinterchanges, it is important to improve our knowledge of the fossil record from key areas and develop phylogenetic hypotheses of about the taxa involved in a robust chronological framework. In this way, the fossil record of small mammals from the early Early and middle Middle Miocene of the north-eastern Aegean island of Chios, at the crossroad between Anatolia and south-eastern Europe, is of key critical importance for the establishment of a more precise biogeographic framework.

In the summer of 2010, two of us (RLA and FK) prospected in Chios Island. After sampling various levels in the Michalos' pit and its surroundings, they were able to locate two layers with Miocene vertebrates [START_REF] López-Antoñanzas | New insights into the vertebrate fauna from the Miocene of Chios (Greece)[END_REF]. The higher fossiliferous horizon was an arenaceous stratum that yielded only a cranial fragment of a Palaeontology Palaeontology large indeterminate mammal. NeverthelessHowever, the a lower in the Keramia Formation one was a a thin argillaceous lens in the Keramia Formation,that produced a diverse vertebrate fauna after screen-washing and sorting, which motivated a return to the site in the summer of 2012 and the exploitation of the lens to near its exhaustion. Altogether, over two metric tons of rock were processed, obtaining as a result nearly 200 teeth of small mammals.

In fact, even though remains of large mammals (comprising a phalange of an indeterminate ruminant, a possible tooth fragment of Cainotherium and another of Sanitherium) and reptilian jaw and osteoderm fragments were retrieved from this new spot, rodents and, to a lesser extent, lagomorphs and insectivores are best represented by far. Preliminary identification of the lagomorphs suggests the presence of Albertona. The insectivore record consists of galericines. Rodents include a wide range of taxa belonging to cricetids, glirids, sciurids and ctenodactylids. Among them, cricetids are the most abundant, in particular species belonging to genera usually present in the eastern Mediterranean region during the early Miocene, such as Cricetodon, Megacricetodon and Democricetodon, but remains of the rare unusual democricetodontine genus Karydomys were also found.

Karydomys is a rare and little diversified democricetodontine, which shows a discontinuous record, geographically as well as chronologically. Its oldest record (Karydomys debruijni) comes from the early Miocene (MN3) of northern Xinjian (China) [START_REF] Maridet | Early Miocene cricetids (Rodentia) from the Junggar basin (Xinjiang, China) and their biochronological implications[END_REF]. This taxonThe genus may have rapidly expanded its range westward, as its presence is attested shortly later in the early Miocene (MN4) of eastern Kazakhstan (Karydomys dzerzhinskii) (Kordikova and De Bruijn, 2001) and Greece (Karydomys boskosi and Karydomys symeonidisi) [START_REF] Theocharopoulos | Late Oligocene--Middle Miocene Democricetodon, Spanocricetodon and Karydomys n. gen. from the Eastern Mediterranean area[END_REF]. Some undescribed findings of Karydomys from the early Miocene (MN 4) of western Anatolia (Ünay & Goktas, 1999;[START_REF] Kaya | Early Miocene stratigraphy of Central West Anatolia, Turkey: implications for the tectonic evolution of the Eastern Aegean area[END_REF] indicate that this area may well have been on a route between central Asia and Greece.

Karydomys may have reached south-western (Karydomys zapfei) (Mein & Freudentahl 1981) Palaeontology Palaeontology and central Europe (Karydomys wigharti) [START_REF] Mörs | A new species of Karydomys (Rodentia, Mammalia) and a systematic re-evaluation of this rare Eurasian Miocene hamster[END_REF][START_REF] Prieto | The rare cricetid rodent Karydomys Theocharopoulos, 2000 in the fissure filling Petersbuch 6 (Middle Miocene, Germany)[END_REF][START_REF] Prieto | First record of Karydomys (Rodentia, Mammalia) from the German part of the North Alpine Foreland Basin[END_REF] by Middle Miocene times, where it became most probably extinct at about 13.8 Ma (Aa single M2 from the fissure filling Petersbuch 6; [START_REF] Prieto | The rare cricetid rodent Karydomys Theocharopoulos, 2000 in the fissure filling Petersbuch 6 (Middle Miocene, Germany)[END_REF].

Because of its geographic position between Asia and Europe as well as its age, somewhat older than the first European occurrences known so far, the presence of Karydomys in the Keramia Formation (""Keramaria" in [START_REF] Besenecker | Neogen und Quartär der Insel Chios (Ägäis)[END_REF]

GEOLOGICAL SETTING

Stratigraphical context

Chios Island is situated in the north-eastern part of the Aegean Sea. The continental Tertiary Cenozoic sediments of Chios are located mainly in the southeastern part of the island, unconformably overlying Mesozoic strata (Fig. 1). The Neogene deposits have been subdivided by [START_REF] Besenecker | Neogen und Quartär der Insel Chios (Ägäis)[END_REF] into four lithostratigraphical units, which are from bottom to top: the Thymiana Formation (Early Miocene), Zyfia Formation (Early--Middle Miocene), Keramia Formation (Middle Miocene) and Nenita Formation (Middle Miocene--Pliocene).

The Keramia Formation is about 120 m thick (Kondopolous et al., 2011). It consists mainly of layers of green-reddish clay and silt with less important layers of green sandstones intercalated [START_REF] Besenecker | Neogen und Quartär der Insel Chios (Ägäis)[END_REF]. The green and reddish colours are characteristic of this formation and make it easily recognizable in the field [START_REF] Besenecker | Neogen und Quartär der Insel Chios (Ägäis)[END_REF]. Besides, the Palaeontology Palaeontology sediments of the Keramia Formation are clearly delimited by a light "Tuff-horizon" below, on the base and by the overlying white limestones of the Nenita Formation on the top [START_REF] Besenecker | Neogen und Quartär der Insel Chios (Ägäis)[END_REF]. [START_REF] Kondopoulou | Palaeomagnetic data and biostratigraphy of the middle Miocene vertebrate locality of Thymiana (Chios island, Greece)[END_REF] conducted a magnetostratigraphical study in a 46 m-thick section of the Keramia Formation in the Michalos' pit area that included the three fossiliferous localities THA, THB and THC. The long reversal dominating the section was tentatively correlated to either with chron C5Br or chron C5Cr based on the biochronological age given then suggested by the mammals found. Later on, [START_REF] Kondopoulou | Rotation history of Chios Island, Greece since the Middle Miocene[END_REF] provided some supplementary magnetostratigraphical data resulting from the sampling of the almost complete Keramia Formation in the Michalos section (about 120 m thickness), also including approximately 10 m of the Zayfa Formation at the bottom of the section. Thus, they include presented information about the lower and uppermost parts of the section that was not considered in [START_REF] Kondopoulou | Palaeomagnetic data and biostratigraphy of the middle Miocene vertebrate locality of Thymiana (Chios island, Greece)[END_REF]. Even if the detailed magnetostratigraphical resultsstudy areis still pending publication [START_REF] Kondopoulou | Rotation history of Chios Island, Greece since the Middle Miocene[END_REF], theirTheir preliminary interpretation of their results could beseem to be in agreement correlating with a correlation of the section to with the interval including chron C5Dr to C5bnC5Bn (Hilgen et al., 2012, fig. 29.9).

Palaeontological background and biochronology

All of the vertebrate specimens yielded so far by the Miocene layers of Chios (at least in modern history) come from the exposure of the Keramia Formation in or close to the brickyard quarry known as "Michalos", which is situated SSE of the village of Thymiana, about 8 km from Chios city. The first finding of vertebrate remains from Michalos' pit was made in 1924 by the geologist GeorgalasGeorgaleas, but [START_REF] Paraskevaidis | Eine obermiocäne fauna von Chios[END_REF]Paraskevaidis ( , 1955) ) was the first to publish on the Miocene vertebrate fauna from Chios (macromammals, Sanitherium and others, but also evidence of tortoises). Additional, but more cursory, observations on Palaeontology Palaeontology similar vertebrate remains (macromammal -particularly sanitheriid and bovid-but also chelonian fragments) from the Neogene of the vicinity of Thymiana were published by Kreatsas (1963). Palaeontological field works in the Michalos area that were conducted in 1967 and 1968 in the framework of a Germano-Hellenic project led contributed to improvea significantly improvement improved of our the understanding of the mammalian fauna from the Keramia Formation (see [START_REF] Melentis | Paläontologische Ausgrabungen auf der Insel Chios (eine vorläufige Mitteilung)[END_REF][START_REF] Tobien | Pälaeontologische Paläontologische Ausgrabungen nach jungtertiären Wirbeltieren auf der Insel Chios (Griechenland) und bei Maragheh (NW-Iran)[END_REF][START_REF] Tobien | Pälaeontologische Paläontologische Ausgrabungen nach jungtertiären Wirbeltieren auf der Insel Chios (Griechenland) und bei Maragheh (NW-Iran)[END_REF][START_REF] Tobien | Wirbeltiergrabungen im Miozän der Insel Chios (Ägäis)[END_REF], 1977[START_REF] Tobien | A note on the skull and mandible of a new choerolophodont mastodon (Proboscidea, Mammalia) from the middle Miocene of Chios (Aegean Sea, Greece)[END_REF][START_REF] Rothausen | Die mittelmiozänen Wirbeltierfundstellen südlich Thymiana (Insel Chios, Ägäis, Griechenland). 2. Teil: Geologie: Die Fundstellen und ihre Abfolge[END_REF][START_REF] Lehmann | Artiodactyle fossilien (Mammalia) aus dem Miozän von Thymiana, Chios[END_REF]. In total, nine fossiliferous layers were recognized at the end of 60's, Thy 1-9, which were and described by [START_REF] Rothausen | Die mittelmiozänen Wirbeltierfundstellen südlich Thymiana (Insel Chios, Ägäis, Griechenland). 2. Teil: Geologie: Die Fundstellen und ihre Abfolge[END_REF]. Most of the material collected then was fragmentary remains of bovids and giraffids, but a nearly complete skull of Gomphotherium angustidens was also discovered (and is still remembered locally!). Micromammals were also found, but were never described in detail and their present whereabouts are is unknown. The same holds true for the lizards, tortoises and fish remains also foundretrieved along. Complementary studies on the vertebrate faunas from Chios arose from Helleno-French field campaigns in 1991 and 1993 [START_REF] Kondopoulou | Palaeomagnetic data and biostratigraphy of the middle Miocene vertebrate locality of Thymiana (Chios island, Greece)[END_REF][START_REF] Koufos | Lophocyon paraskevaidisi, a new viverrid (Carnivora, Mammalia) from the Middle Miocene of Chios Island, Greece[END_REF]Bonis et al., 1997aBonis et al., , 1997b[START_REF] Bonis | Ruminants (Bovidae and Tragulidae) from the middle Miocene (MN5) of the island of Chios, Aegean sea (Greece)[END_REF][START_REF] López-Antoñanzas | Presence of a ctenodactylid (Rodentia) in the Keramaria Formation (Middle Miocene) of Chios Island (Greece)[END_REF].

In addition to the nine fossiliferous levels described by Rothausen (1973), three new levels were found in the 90's by the Hellenic-French teamon this occasion, "Thymiana A" (THA), "Thymiana B" (THB) and "Thymiana C" (THC) (Kondoupulou et al., 1993). Besides a few interesting macromammalian remains (mostly of sanitheriid and bovid affinities), some of them well preserved, these fieldworks resulted in the collection building up of a rich micromammal faunacollection, which is yet to be studied in its entirety.

Our main fossiliferous layer is situated on the coast, about 340 meters SSW from the main brick building. It does not correspond to any of the localities previously sampled. The stratigraphical position of the new layer suggests it may be coeval with the most basal Palaeontology Palaeontology fossiliferous layers (Thy 1 and Thy 5), but older than the other ones. We name it informally Thy 0.

The mammalian fauna of the Keramia Formation is considered as from the biozone MN 5 [START_REF] Mein | Updating of MN zones[END_REF][START_REF] Steininger | European Neogene marine/continental chronologic correlations[END_REF][START_REF] Bruijn | Report of the RCMNS working group on fossil mammals, Reisenburg 1990[END_REF]Bonis et al., 1997aBonis et al., , 1997b;;[START_REF] Bonis | Ruminants (Bovidae and Tragulidae) from the middle Miocene (MN5) of the island of Chios, Aegean sea (Greece)[END_REF][START_REF] Bonis | The Miocene large mammal succession in Greece[END_REF][START_REF] Made | Intercontinental relationship Europe-Africa and the Indian Subcontinent[END_REF][START_REF] Koufos | The Neogene mammal localities of Greece: faunas, chronology and biostratigraphy[END_REF]. This dating age is based both on the macromammals and the evolutionary stage and composition of the micromammal fauna, notably the cricetids. However, the macromammal remains from this area are fragmentary and the micromammals have never been properly described. In fact, only [START_REF] Tobien | Pälaeontologische Paläontologische Ausgrabungen nach jungtertiären Wirbeltieren auf der Insel Chios (Griechenland) und bei Maragheh (NW-Iran)[END_REF] and Bonis et al. (1997a) listed the micromammals that they recognized and only a single group of rodents, the ctenodactylines, has been the object of a detailed study [START_REF] López-Antoñanzas | Presence of a ctenodactylid (Rodentia) in the Keramaria Formation (Middle Miocene) of Chios Island (Greece)[END_REF]. Kondoupoulou et al. (1993) showed that the fossiliferous levels THA, THB and THC were included in a long reverse episode that, considering the MN5 age provided by the mammalian fauna, could be correlated with the Chron C5Br, which in turn provided an age of about 15.5 Ma [START_REF] Koufos | The Neogene mammal localities of Greece: faunas, chronology and biostratigraphy[END_REF]. For instance, the micromammals from THA and THC were supposed to be younger than that those of Aliveri (MN 4) but quite similar to the to that of Komotini (MN 5) assemblage (Bonis et al., 1997a;[START_REF] Bonis | The Miocene large mammal succession in Greece[END_REF]. Considering that our fossiliferous level Thymiana 0 is at the base of the Keramia Formation, it may be correlated with the Chron C5Cr, which would correspond to an Early Miocene age of 16.7-17.23 Ma.

MATERIAL AND METHODS

Remains of micromammals were obtained by screen washing almost 2 tons of sediment with a mesh light of 0.5 mm. First, second and third lower molars are designated as m1, m2 and m3, and first, second and third upper molars as M1, M2 and M3, respectively. The Palaeontology Palaeontology terminology used in the tooth descriptions follows those of [START_REF] Freudenthal | The genus Pseudocricetodon (Cricetidae, Mammalia) in the Upper Oligocene of the province of Teruel (Spain)[END_REF] and [START_REF] López-Antoñanzas | New species of Hispanomys (Rodentia, Cricetidae) from the Upper Miocene of Batallones (Madrid, Spain)[END_REF]. Measurements of the occlusal surface of the teeth (maximum length [L] and maximum width [W]) were obtained with a Nikon digital counter CM-6S measuring device, following the method of van de Weerd (1976) (Table 1). All measurements are given in millimetres. The teeth of the species of Karydomys described in this work were compared with all the all known species belonging to this genus. Scans and SEMs of the teeth of the specimens have been taken with a CT-SCAN Nikon XT H-160 and a Scanning Electron Microscope FEI QUANTA 200.

All the species of Karydomys known to date were included in the ingroup. These are: Karydomys K. debruijni, Karydomys K. dzerzhinskii, Karydomys K. symeonidisi, Karydomys K. boskosi, Karydomys K. wigharti, Karydomys K. zapfei and Karydomys K. strati. sp. nov. from Chios. In addition, a selection of closely related non-congeneric species were added to the ingroup so as to test the monophyly of the genus Karydomys and to clear up its phylogenetic relationships with species currently attributed to Democricetodon, from which Karydomys may have evolved, and Cricetodon. [START_REF] Maddison | Mesquite: A Modular System for Evolutionary Analysis[END_REF]) and the analysis was run in TNT [START_REF] Goloboff | TNT, a free program for phylogenetic analysis[END_REF] with the "traditional Palaeontology Palaeontology search" option (using TBR). Owing to the lack of a priori information, all characters were unordered and equally weighted (Fitch optimality criterion). As some species are known so far from only a few specimens, the influence of intraspecific variation in the scoring of the characters could not be assessed. Branch support was estimated through two complementary indices: Bremer Support [START_REF] Bremer | Branch support and tree stability[END_REF]) and Relative Bremer Support [START_REF] Goloboff | Methods for quick consensus estimation[END_REF].

All the specimens are provisionally stored at the University of Montpellier, Montpellier (France)

SYSTEMATIC PALAEONTOLOGY

Order RODENTIA Bowdich, 1821 Family CRICETIDAE Fischer von Waldheim, 1817

Subfamily DEMOCRICETODONTINAE Lindsay, 1987 Genus KARYDOMYS Theocharopoulos, 2000 Type species. Karydomys symeonidisi [START_REF] Theocharopoulos | Late Oligocene--Middle Miocene Democricetodon, Spanocricetodon and Karydomys n. gen. from the Eastern Mediterranean area[END_REF] Karydomys strati sp. nov. M2 Three teeth, two of them complete (ThyUM Thy 0-30 and ThyUM Thy 0-48) and the other one damaged (ThyUM Thy 0-54), have been found. The teeth show well-developed labial and lingual anterolophs. The labial anteroloph is connected to the base of the paracone, enclosing a narrow anterosinus, whereas the lingual one reaches the base of the protocone enclosing the protosinus. The protolophule is double, but its degree of development varies from one specimen to another. Specimen ThyUM Thy 0-30 shows the anterior protolophule slightly interrupted and weaker than the posterior one. ThyUM Thy 0-48 has the anterior protolophule strong, whereas the posterior one is weaker and interrupted. ThyUM Thy 0-54 has both anterior and posterior protolophules complete. All specimens have a long and narrow mesoloph that ends with a mesostyle at the labial border of the teeth. The backward paracone spur is short but strong and reaches the mesostyle in two out of the four specimens available. The teeth have a double metalophule with the posterior one stronger than the anterior one. Both the anterior and the posterior metalophules are nearly longitudinal and they can even form an additional longitudinal crest on their own (specimen ThyUM Thy 0-30).

LSID.urn:lsid:zoobank.org:act:0958B82F-9788-4DE3-94EF-6287172E1103

The posteroloph is short and connects to the posterior metalophule. It nearly reaches the metacone, enclosing a small posterosinus. The roots of these teeth are not preserved.

Cladistic analysis

The cladistic analysis including all species of Karydomys as well as relevant species currently placed in the genera Democricetodon and Cricetodon yielded a single most parsimonious tree with a length of 86 and a relatively high degree of homoplasy (CI = 0.512; RI = 0.806). Our results (Fig. 5

DISCUSSION

The examination of the new rodent remains from Chios has allowed to evidence the presence ofrevealed eight molars (Figs 2-3) belonging to a middle sized Karydomys (Fig. 4) but different from the molars in all theof any species of this genus known so far. Karydomys strati sp. nov. is morphologically close to the two known species from Karydia. However, it shows some important differences, particularly concerning the protolophule and the metalophule on the M1 and M2 and the degree of development of the mesolophids, which prevent to consider it as belonging to either of them. The presence of a double metalophule on the M2 (Fig. 6) may suggest that the new species from Chios could be, in fact, slightly older than Karydomys symeonidisi and Karydomys boskosi, in which the anterior metalophule is lost not only on the M1 but also on the M2. The absence, on the M1 of Karydomys strati, of the anterior protolophule, which is present in Karydomys symeonidisi , and the presence of a spur on the anterolophule on the M1, a primitive character absent in Karydomys K.arydomys boskosi, is consistent with this hypothesis. The presence of a posterior metalophule on the M2 of Karydomys strati suggest that it is more evolved than Karydomys Palaeontology Palaeontology K.arydomys dzerzhinskii and Karydomys K.arydomys debruijni (Fig. 6), which are the oldest species of Karydomys. In addition, Karydomys from Chios is distinct from Middle Miocene species such as Karydomys K.arydomys wigharti and Karydomys K.arydomys zapfei in being noticeably smaller, in lacking the anterior protolophule on the M1 (present in Karydomys K. wigharti), in having a well-developed posterior paracone spur on the M1 and M2 as well as in the presence of the ectomesolophid on the m1 (Fig. 6).

The genus Karydomys was erected by [START_REF] Theocharopoulos | Late Oligocene--Middle Miocene Democricetodon, Spanocricetodon and Karydomys n. gen. from the Eastern Mediterranean area[END_REF] on the basis of some characters such as the presence of a small posterosinus and well-developed ectolophs on the first two upper molars (in some of the taxa), the reduction of the size of the third molars and the presence of a small, blade-like anteroconid situated very close to the protoconid and the metaconid on the first lower molar. However, as pointed out by [START_REF] Maridet | Early Miocene cricetids (Rodentia) from the Junggar basin (Xinjiang, China) and their biochronological implications[END_REF], some of these characters, such as the presence of a small posterosinus, resulting from a posterior position of the metalophule, as well as the development of the ectolophs (posterior paracone spur in the present work), are not present in all the species of the genus. Therefore, [START_REF] Maridet | Early Miocene cricetids (Rodentia) from the Junggar basin (Xinjiang, China) and their biochronological implications[END_REF] suggested that the diagnosis of the genus had to be revised when more material would becoame available. Even though we concur with [START_REF] Maridet | Early Miocene cricetids (Rodentia) from the Junggar basin (Xinjiang, China) and their biochronological implications[END_REF] that there are a number of issues related to the diagnosis of the genus Karydomys, we are inclined to maintain this taxon in its current specific composition as the species of Karydomys form a monophyletic grouping in our analysis. The clade Karydomys shares indeed one exclusive synapomorphy:, which is to have a slightly divided or "crest-like" anterocone on the M1 (3 (0 1)). In fact, the M1 of Karydomys are ALSOcharacterized by a wider and flater anterocone more independent from the anteroloph than those ofin Democricetodon, in which it is a well-defined cusp that may fuse with the anteroloph bywith wear. The presence of a short lingual anterolophid (23 (0 1)) on the m1 supports also the clade, but this is shown by someoccurs in some species of Democricetodon as well (e.g. Democricetodon Palaeontology Palaeontology D.emocricetodon anatolicus of our ingroup). A very interesting synapomorphy is found in the connection of the anterior metalophulid anterior on the m1. Thus, itThis crest joins the a distinct anterolophulid in Democricetodon (24(0 1)), whereas itbut connects directly connects to the anteroconid or to a tiny anterolophulid in Karydomys (24 (1 2)). This latter synapomorphy feature is also shared by the members of the genus Cricetodon.

According to our results Karydomys split early into two different lineages. One constituted by the central Asiatic Asian (Karydomys debruijni and Karydomys dzerzhinskii) and Greek species (Karydomys symeonidisi, Karydomys boskosi and Karydomys strati sp. nov.) species, which we term herein the "eastern lineage", and the other one formed by the species from Germany and France (Karydomys K.arydomys wigharti and Karydomys K.arydomys zapfei), the "western lineage". [START_REF] Maridet | Early Miocene cricetids (Rodentia) from the Junggar basin (Xinjiang, China) and their biochronological implications[END_REF] had pointed out the morphological differences between the the species of Karydomys, those from western and central Europe (France and Germany) and south-eastern Europe (Greece) , on the one side, and those the species from central Asia (Kazakhstan and north-western China) on the other, on the other side. The latter were considered the least derived particularly on the basis of the morphology of the M2. Our results show a basal position of the two central Asiatic Asian species of Karydomys (Karydomys K.arydomys debruijni and Karydomys K.arydomys dzerzhinskii) with respect to the Greek ones, but not regarding the western European species Karydomys K.arydomys wigharti and Karydomys K.arydomys zapfei, which belong to a separate lineage. The cladogram shows sister group relationships between Karydomys dzerzhinski from Kazaksthan and the clade composed by the three Greek species (Karydomys Karydomys symeonidisi (KarydomysKarydomys strati sp. nov. + Karydomys Karydomys boskosi)). These results are consistent with the suggestion of Kordikova and de Bruijn (2001) about a close relationship between Karydomys Karydomys dzerzhinski and Karydomys Karydomys symeonidisi, with the former a plausible ancestor of the later. Our results also

Palaeontology Palaeontology

show that Karydomys wigharti is sister species of Karydomys Karydomys zapfei. [START_REF] Mörs | A new species of Karydomys (Rodentia, Mammalia) and a systematic re-evaluation of this rare Eurasian Miocene hamster[END_REF] emphasized the morphological affinities between these two speciesthem. Some synapomorphies of the species of Karydomys for central Asia and south-eastern Europe allow for differentiating them from the taxa from western and central Europe. In particular, the presence of a short but distinct backward paracone spur on the M1 (8 (0 1), a derived character state, and the presence of a well-developed ectomesolophid on the m1 (27 (0 1)), another derived character state, are characters features that are usually lacking on the two western and central European species Karydomys wigharti and Karydomys zapfei. However, these are not clear-cut discriminators as the several M1 of Karydomys debruijini show a backward paracone spur that varies from more or less short to absent altogether, and the ectomesolophid is equally variable in the its degree of development on the m1 of in Karydomys wigharti. Besides morphology, the western and central European species are also larger than the other species of Karydomys and, indeed, Democricetodon. The grouping of the Greek species of Karydomys is supported by stout cusps (2 (0 1)), which is a parallelism with the western and central European species. The Greek species also show a welldeveloped backward paracone spur on the M2 (15 ((0 1)), which is a character state incipient in Karydomys dzerzhinski.

The diagnostic characters provided by [START_REF] Theocharopoulos | Late Oligocene--Middle Miocene Democricetodon, Spanocricetodon and Karydomys n. gen. from the Eastern Mediterranean area[END_REF] to differentiate Karydomys from Democricetodon are not valid for all taxaspecies. On one side, tThe presence of a small anteroconid, which was used to discriminate the two genera, is a character also shared seen with in various species of Democricetodon. On the other sideFurther, the alleged presence of better developed ectolophs in Karydomys than in

CONCLUSION

The new species Karydomys strati sp. nov. has been erected in this work to accommodate new remains of Karydomys recently recovered from the Miocene of Chios. According to our phylogenetic analysis, the genus Karydomys split early into two different lineages, an "eastern stock" that includes the central Asian and Greek species and a "western lineage", which is constituted by the western and central European species of the genus. Karydomys strati belongs to the so-called "eastern lineage"stock". This quite relatively large-sized democricetodontine rodent is characterized by having a labial spur on the anterolophule and the lacking of the anterior protolophule on the M1 and as well as by the presence of a double metalophule on the M2. This latter character suggests that Karydomys strati is more evolved than Karydomys K.arydomys dzerzhinskii and Karydomys K.arydomys debruijni, which are are both lackingdevoid of the posterior metalophule, but less evolved than the Greek species Karydomys K. symeonidisi and Karydomys K. boskosi, which areare both lacking the anterior metalophule.

The presence of Karydomys is of interest from a biostratigraphical point of view. The Keramia Formation has been usually given a Middle Miocene age. However, the evolutionary stage of the new species of Karydomys that it yields suggests that the its stratigraphical level it comes from could be, in fact, slightly older than those from which Karydomys K.arydomys

  of Chios is not a trivial record. The aim of the present work is to provide a description of the teeth of the new species of Karydomys discovered from the Keramia Formation of Chios Island and seize the opportunity to try and shed light on the evolutionary history of this group of rodents by deciphering their phylogenetic relationships with other Democricetodontinae and representative Cricetodontinae, and touching upon the possible dispersal routes of this hamster.

Figs 2- 3

 3 Figs 2-3

  ) evidence two main lineages thatgroups separated from one another at the most Palaeontology Palaeontology basal node. The first one corresponds to all the species of Cricetodon included in this analysis, which form a monophyletic group, whereas the second is formed byincludesencompasses the various species of Democricetodon taken into account in this work and all known species of Karydomys. However, while Karydomys forms a clade within the latter lineage, Democricetodon constitutes an array of successive sister-species to Karydomys. BesidesFurther, two lineages diverge at the basal node of Karydomys: one constituted by the western Eurasiatic Eurasian species (Karydomys wigharti + Karydomys zapfei) and the other by the eastern Eurasiatic Eurasian ones (Karydomys debruijni + more derived species).

  Democricetodon , is actually lacking in the two western and central European members of Karydomys (Karydomys K.arydomys wigharti and Karydomys K.arydomys zapfei) but present in some species of Democricetodon (e.g. Democricetodon D.emocricetodon anatolicus), Palaeontology Palaeontology whose which have the ectolophs are well -developed. As mentioned above, only one exclusive synapomophy backs up the clade Karydomys, which is a slightly divided or "crestlike" anterocone on the M1. We have reservations about the adequacy of such a unique character to justify the legitimacy of the genus Karydomys. However, the differences between Democricetodon and Karydomys regarding the nature of the connection of the anterior metalophulid anterior should also be taken into account. The species currently attributed to Karydomys may as well be seen as pertaining to Democricetodon, as derived members of the genus. At this point, however, we refrain for formally synonymising Karydomys with Democricetodon given the incomplete nature of our ingroup. Should a future, more comprehensive, phylogenetic analysis of the species of Democricetodon and Karydomys yield a pattern of results in line with our own (i.e. Democricetodon forming a paraphyletic array of species relative to a Karydomys clade) then the merits of the recognition of the genus Karydomys will have to be seriously questioned. In any case, the close relationships between the genera Karydomys and Democricetodon suspected by[START_REF] Theocharopoulos | Late Oligocene--Middle Miocene Democricetodon, Spanocricetodon and Karydomys n. gen. from the Eastern Mediterranean area[END_REF] are confirmed.The teeth of the taxa belonging to Cricetodon are morphologically quite different from those of Democricetodon and Karydomys. Our cladogram clearly supports the monophyly of Cricetodon. The species of Cricetodon included in the ingroup share some exclusive synapomorphies. They have the anterocone strongly divided (3 (0 1)) and a short mesoloph (9 (0 1)) on the M1. Their m1 are characterized by having a large anteroconid (22(0 1)) and by usually lacking the lingual anterolophid (23 (0 1)). With respect to the m2, the less derived members of the group they have a weak lingual anterolophid in the less derived members of the group (28 (0 1)), which completely disappear in the more evolved members representatives of the clade (28 (1 2)). Their m3 show a more or less circular protosinusid (31 (0 1)) instead of having it retracted and directed forward as is the case inPalaeontology PalaeontologyDemocricetodon and Karydomys. However, to confirm or refute the monophyly of this clade, a more comprehensive cladistic analysis that would include all the species belonging to Cricetodon and closely related genera such as Hispanomys or Byzantiniathe subfamily Cricetodontinae is necessary.

  Figure captions

  These are Democricetodon anatolicus,

	Democricetodon D. doukasi, Democricetodon D. gracilis, Democricetodon D. franconicus,
	Democricetodon D. mutilus, Cricetodon versteegi, Cricetodon C. tobieni, Cricetodon C.
	kasapligili, Cricetodon C. aliveriensis, Cricetodon C. trallesensis, Cricetodon C. orientalis,
	Cricetodon C. meini, Cricetodon C. engesseri, Cricetodon C. hungaricus, Cricetodon C.
	bolligeri. Eucricetodon wangae, a primitive Cricetidaecricetid rodent, was selected as
	outgroup. A total of 32 phylogenetically informative characters (mainly of dental
	morphology) have been coded (see appendix S1 S1). 19 characters are binary, whereas 13 are
	multistate. The data matrix (archived in the Dryad Digital Data Repository: López-
	Antoñanzas et al. 2018) see appendix S2) was built using Mesquite 23.6 04

Palaeontology

Acknowledgements. We sincerely thank I. Antoñanzas-Asso, E. López-Antoñanzas and J. A.

Molina

-Anadón for their help during the field work and/or the sorting of sediment. Permission to conduct field research in the Island of Chios carried out by R. L-A. and F. K. was granted by the Greek Institute of Geology and Mineral Exploration (Acharnae). Permission to prospect the private Michalos brickyard quarry was granted ensured by Stratos Asmanis, who made our kindly support us during the sojourns in Chios most enjoyable. T. Mörs (Swedish Museum of Natural History, Stockholm, Sweden), S. Thomas (The Palaeontological Association, Durham, United Kingdom) and an anonymous reviewer enhanced this work through careful, critical reading. M. Furió, A. García, C. Paradela, and L. Tormo (Museo nacional de Ciencias naturales-CSIC, Madrid) nicely were kind enough to take took the µ CT scan images and SEMs.

This work is dedicated to the memory of my beloved father, M. anuel López Gálvez, who will live forever in our hearts.

DATA ARCHIVING STATEMENT

This published work and the nomenclatural act it contains, have been registered in ZooBank: http://zoobank.org/References/81D56B1D-2B00-4FCB-90D7-2C1D15EA0B7B Data for this study are available in the Dryad Digital Repository: http://datadryad.org/review?doi=doi:10.5061/dryad.m086rm8 [please note that the


Ari Grossman

Ran Calvo

Raquel López-Antoñanzas

Fabien Knoll

Gideon Hartman

Rivka Rabinovich

Ari Grossman, 

Raquel Lopez-Antonanzas

Fabien Knol

Hartman

First record of Sivameryx (Cetartiodactyla, Anthracotheriidae) from the lower Miocene of Israel highlights the importance of the Levantine Corridor as a dispersal route between Eurasia and Africa

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Multiple mammalian orders and families appear to have migrated from Africa to Eurasia 41 during the Early and Middle Miocene in a series of relatively rapid migration events (e.g. Cote et 42 al., 2018;Leakey et al., 2011). An uncertain but substantial number of African taxa such as 43 proboscideans migrated out of Africa roughly simultaneously (e.g. Sanders et al., 2010;Sanders 44 and [START_REF] Sanders | New proboscideans from the early Miocene of Wadi Moghara, 366 Egypt[END_REF]. Direct fossil evidence for these migrations from sites that lie between Africa 45 and Eurasia are rare but crucial for reconstructing biogeographic patterns of dispersal. The 46 Levantine Corridor, located between Africa and Eurasia, provides the best case for studying 47 such patterns [START_REF] Tchernov | Miocene mammals of the Negev (Israel)[END_REF]. Preliminary descriptions recognized 19 fossil Early Comparative Description-the tooth is a nearly complete crown with a slightly broken 130 anterior (=mesial) cingulum and the anterior part of the roots also sheared. The molar is bucco-131 lingually (21.8mm) wider than it is mesio-distally long (19.8mm). The crown is brachyodont and 132 the cusps are selenodont and high, giving the crown a tall appearance. There are four main 133 cusps (paracone, protocone, metacone, metaconule), and a fifth very small paraconule, a 134 distinctive character of Sivameryx referred to as quasi-pentacuspidate by some authors 135 [START_REF] Holroyd | Anthracotheriidae. 319 Cenozoic Mammals of Africa[END_REF][START_REF] Pickford | Revision of the Neogene Anthracotheriidae of Africa[END_REF]. The tips of the metacone and the paracone of HUJI KJ 31 136 pinch-in so that the tips of the cusps are close together. This pinching exaggerates the sloping 137 of the buccal sides of each buccal cusp contrasting with the less sloped lingual sides of the 138 lingual cusps. This is especially visible in the metacone. A looping mesostyle are connects the 139 two buccal cusps. The parastyle is partially broken but was clearly also looping and prominent. larger than M2 (Fig. 3). HUJI KJ 31 falls within the cluster that includes M2 of S. africanus, S.

191 moneyi, and S. palaeindicus (Fig. 3), and thus we recognize it as an M2. unknown. Jaggermeryx naida is a monospecific genus identified only from dentaries and lower 199 dentition found at Wadi Moghra in Egypt [START_REF] Miller | Anthracotheres from Wadi Moghra, early Miocene, Egypt[END_REF]. As such, direct comparisons with 200 HUJI KJ 31 are impossible. However, J. naida differs from known lower dentition of Sivameryx 201 by its bunodont rather than selenodont dentition and overall greater size [START_REF] Miller | Anthracotheres from Wadi Moghra, early Miocene, Egypt[END_REF]. J.

202

naida is an African genus. [START_REF] Miller | Anthracotheres from Wadi Moghra, early Miocene, Egypt[END_REF] suggested that this genus is derived from older 203 African anthracotheres found in Oligocene deposits of the Fayum in Egypt.

204

Brachyodus is considered a descendant of Bothriogenys from the Oligocene of the 205 Fayum in Egypt and thus of African origin [START_REF] Holroyd | Anthracotheriidae. 319 Cenozoic Mammals of Africa[END_REF]. Brachyodus currently includes 206 three species in Africa; B. depreteti from Wadi Moghara and Siwa in Egypt [START_REF] Miller | Anthracotheres from Wadi Moghra, early Miocene, Egypt[END_REF] 207 [START_REF] Pickford | Revision of the Neogene Anthracotheriidae of Africa[END_REF], and from Sperrgebiet in Namibia [START_REF] Pickford | Anthracotheriidae from the Early Miocene deposits of the northern Sperrgebiet, 355 Namibia. Geology and palaeobiology of the Northern Sperrgebiet, Namibia[END_REF]; B. mogharensis found only at 208 Wadi Moghra [START_REF] Miller | Anthracotheres from Wadi Moghra, early Miocene, Egypt[END_REF][START_REF] Pickford | Revision of the Neogene Anthracotheriidae of Africa[END_REF]

  [START_REF] Pickford | Revision of the Neogene Anthracotheriidae of Africa[END_REF];[START_REF] Lihoreau | Systématique et paléoécologie des Anthracotheriidae [Artiodactyla; Suiformes] du 327 mio-pliocène de l'ancien monde: implications paléobiogéographiques[END_REF],[START_REF] Holroyd | Anthracotheriidae. 319 Cenozoic Mammals of Africa[END_REF], Lihoreau 119 et al. (2016). Medium to small in size; canines sexually dimorphic; p1 double rooted; lower 120 molars selenodont with anterior crests of labial cusps reaching lingual surface of crown, often 121 ending in a small cuspule; four crests from the metaconid; lingual cusps of lower molars 122 mediolaterally compressed; talonid of m3 loop-like and strongly obliquely oriented; upper 123 molars with four main cusps and a paraconule almost fused with protocone and of similar 124 height (=quasi-pentacuspidate); looplike parastyles and mesostyles; two distal crests from 125 protocone; symphysis reaches back to level of p1; no genial spine; postcanine diastema long, 126 with a flange-like protuberance leaning laterally; enamel microstructure is a mono-zonal radial 127 Schmelzmuster (not equivalent to the cetartiodactyl plesiomorph condition). Page 7 of 28 Society of Vertebrate Paleontology Journal of Vertebrate Paleontology: For Review Only New Material-HUJI KJ 31: Right second molar (M2) (Fig. 2) 129

140

  The metastyle of HUJI KJ 31 is relatively smaller than the mesostyle or parastyle. The 141 preparacristule is broad but slightly abraded. It wraps around the mesiolingual side of the 142 paracone to merge with the parastyle. Both the metacone and the paracone have distinct 143 bulbous ribs descending buccally; that of the paracone appears larger although this could be an 144 artefact of the degree of erosion of the metacone. A median transverse valley separates the 145 mesial and distal portions of the toot. The narrow base of the valley is approximately at the 146 level of the cervix of the tooth. The median transverse valley is enclosed buccally by the 147 mesostyle, and continues lingually to terminate at the lingual cingulum. The mesial cingulum 148 begins at the mesial end of the parastyle where the preparacristule merges with the paracone. 149 The mesial cingulum is continuous with a very prominent and arcuate cingulum that surrounds Page 8 of 28 Society of Vertebrate Paleontology Journal of Vertebrate Paleontology: For Review Only the protocone lingually. This protocone cingulum merges with a second arcuate cingulum that 151 surrounds the metaconule, and the two cingula meet at the termination of the median 152 transverse valley. The metaconule cingulum is continuous with a distal cingulum that extends to 153 the distal part of the metastyle. Thus, the cingula form a single, shelf-like cingulum covering all 154 but the buccal aspect of the tooth. 155 HUJI KJ 31 shares with other bothriodontine anthracotheres an upper molar mesostyle 156 invaded by the median transverse valley and selenodont crescenteric cusps. Anthracotheriinae 157 differ by their accessory protostyle on the mesial cingulum, and relatively bunodont upper 158 molar cusps. Micorbunodontinae differ because they lack the median transverse valley invading 159 the mesostyle, 160 Members of the tribe Merycopotamini (Afromeryx, Sivameryx, Hemimeryx, 161 Merycopotamus, Libycosaurus) are distinguished in their upper molars from other 162 bothriodontine anthracotheres by a preparacrista that connects labially with the parastyle, lack 163 of ectocristyle, and development of the molar entostyle (Lihoreau et al., 2016). All characters 164 observed in HUJI KJ 31. We thus restrict further comparisons primarily to Merycopotamini with 165 a few additions. 166 We place HUJI KJ 31 in Sivameryx because it is a five-cusped upper molar with a reduced 167 paraconule (i.e. quasi-pentascuspidate). It also shares with Sivameryx a loop-like mesostyle and 168 a strongly developed lingual cingulum of the protocone. 11 190

  genera of anthracotheres are known from Africa: Brachyodus, 195 Sivameryx, Afromeryx, and Jaggermeryx. The distribution of the species of these genera 196 suggests that African anthracotheres dispersed from Africa to Eurasia, while Eurasian 197 anthracotheres dispersed to Africa. However, the exact pathways enabling such dispersals are 198

397C.

  FIGURE 2. SEM and schematic drawing of HUJI KJ 31-M2 of Sivameryx palaeindicus in occlusal

FIGURE 1 .

 1 FIGURE 1. Location map of the Kamus Junction (KJ) locality in the Yamin Plain, northern Negev, Israel. A. Genreal location of northern Negev, Israel. B. Hazeva Formation outcrops in the northern Negev. Kamus Junction area is marked by a blue star. C. The Hazeva Formation fills the Yamin Plain with all of its members. In the Kamus Junction area the upper parts of Zefa Member are overlain by clastic units of the Rotem Member. Small unconformity separates the lower and upper parts of the Rotem Member. Green dot marks the location of the upper level of KJ site where HUJI KJ 31 was found. D. Topographic elevation of KJ site where HUJI KJ 31 was found (Green dot). E. Columnar stratigraphic section in the Kamus Junction locality. 103x58mm (300 x 300 DPI)

  ; and B. aequatorialis in various localities in 209 East Africa (Kalodirr, Rusinga, Loperot, and Locherangan, Kenya, and Moroto, Uganda) (Holroyd 210 et al., 2010). Records of Brachyodus in Eurasia include: B. onoideus from Early Miocene deposits Hazeva Formation outcrops in the northern Negev. Kamus Junction area is marked by a

	Page 11 of 28	Journal of Vertebrate Paleontology: For Review Only Journal of Vertebrate Paleontology: For Review Only
		FIGURE CAPTIONS
	392	FIGURE 1. Location map of the Kamus Junction (KJ) locality in the Yamin Plain, northern Negev,
	393	Israel.
	394	A. General location of northern Negev, Israel.
		Society of Vertebrate Paleontology Society of Vertebrate Paleontology

395

B.

396 blue star.

Table 1

 1

	Page 21 of 28
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	415
	416

TABLE 1 .

 1 Measurements of Sivameryx spp. Upper molars

	Specimen No.	MD	BL	Tooth position Reference	Site
	KJ 31	19.8 21.8	M2	This paper	Kamus Junction
			Sivameryx moneyi
	CUWM 64AB	19.92 18.27	M1	Miller et al. 2014	Wadi Moghara
	CUWM 64AB	23.08 21.18	M2	Miller et al. 2014	Wadi Moghara
	CUWM 64AB	23.44 22.46	M3	Miller et al. 2014	Wadi Moghara
	CUWM 70	17.5 17.5	M1	Miller et al. 2014	Wadi Moghara
	CUWM 70	22.11 21.55	M2	Miller et al. 2014	Wadi Moghara
	DPC 4066	21.47 22.34	M2	Miller et al. 2014	Wadi Moghara
	DPC 4066	24.04 24.86	M3	Miller et al. 2014	Wadi Moghara
	DPC 5979	20.71 20.89	M2	Miller et al. 2014	Wadi Moghara
	DPC 6243	15.5 16.35	M1	Miller et al. 2014	Wadi Moghara
	DPC 6243	23.12 20.81	M2	Miller et al. 2014	Wadi Moghara
	DPC 6289	21.1 21.32	M3	Miller et al. 2014	Wadi Moghara
	DPC 7659	25.35 22.89	M3	Miller et al. 2014	Wadi Moghara

Journal of the Palaeontological Society of India 20:219 -223.

Society of Vertebrate Paleontology Journal of Vertebrate Paleontology: For Review Only Society of Vertebrate Paleontology Journal of Vertebrate Paleontology: For Review Only