True frogs of the genus Rana are widely used as model organisms in studies of development, genetics, physiology, ecology, behavior, and evolution. Comparative studies among the more than 100 species of Rana rely on an understanding of the evolutionary history and patterns of diversification of the group. We estimate a well-resolved, time-calibrated phylogeny from sequences of six nuclear and three mitochondrial loci sampled from most species of Rana, and use that phylogeny to clarify the group's diversification and global biogeography. Our analyses consistently support an "Out of Asia" pattern with two independent dispersals of Rana from East Asia to North America via Beringian land bridges. The more species-rich lineage of New World Rana appears to have experienced a rapid radiation following its colonization of the New World, especially with its expansion into montane and tropical areas of Mexico, Central America, and South America. In contrast, Old World Rana exhibit different trajectories of diversification; diversification in the Old World began very slowly and later underwent a distinct increase in speciation rate around 29-18 Ma. Net diversification is associated with environmental changes and especially intensive tectonic movements along the Asian margin from the Oligocene to early Miocene. Our phylogeny further suggests that previous classifications were misled by morphological homoplasy and plesiomorphic color patterns, as well as a reliance primarily on mitochondrial genes. We provide a phylogenetic taxonomy based on analyses of multiple nuclear and mitochondrial gene loci. [Amphibians; biogeography; diversification rate; Holarctic; transcontinental dispersal.

We describe four new species of Asian Clawed salamanders of the genus Onychodactylus (Caudata: Hynobiidae), basedon fresh material collected during fieldwork in Japan, Korea, the Russian Far East and northeastern China between 2003and 2010, as well as older voucher specimens deposited in several museums. Our analyses comprise all species currentlyrecognized within this genus across its entire distribution range. We follow an integrative taxonomic approach bycombining detailed morphological comparative analyses with molecular phylogenetic analyses. We find significantdifferences among species in this genus, based on morphological and molecular data, which resulted in the recognitionand description of four new species within this genus. The new species have uncorrected molecular divergences of over4.5–7.4% and 1.9–4.1% to their closest relatives in the mitochondrial COI and 16S rRNA genes respectively. In themolecular analyses, we found two very divergent lineages in Korea and Japan that need further investigation, as detailedmorphological data are not available for them. We also discuss our approach to delimit species on salamanders. For thenew species described in this group we evaluate their threat status according to IUCN criteria: O. koreanus sp. nov. Min,Poyarkov & Vieites and O. nipponoborealis sp. nov. Kuro-o, Poyarkov & Vieites are classified as Least Concern, whileO. zhaoermii sp. nov. Che, Poyarkov & Yan and O. zhangyapingi sp. nov. Che, Poyarkov, Li & Yan are classified as Vulnerable (Vu2a).

We studied skull, vertebral column, and limb skeleton development in Japanese clawed sala mander Onychodactylus japonicus (Hynobiidae). The study is based on the ontogenetic series of embryos and larvae obtained from wild captured adults by artificial induction of breeding using hormonal stimulation. The first stages of the skeleton formation in O. japonicus are shifted to the late embryonic period and hatching lar vae already possess a well ossified vertebral column, large number of skull ossifications and show signs of ossi fication in the forelimb skeleton. Compared to the primitive pattern of the skeleton development typical for other hynobiid salamanders, O. japonicus shows a number of heterochronies related to embryonization. In particular, this species is characterized by an earlier ossification of the vertebral column compared to that of the skull and by the delayed development and early reduction of the coronoid. Our results, along with the pre viously reported data on the skeleton development in the Fischer's clawed salamander O. fischeri (Smirnov and Vassilieva, 2002), indicate that the genus Onychodactylus is characterized by the loss or reduction of sev eral skeletal features typically found at early larval stages in other Hynobiidae species. In particular, provi sional bones (especially the coronoid) and their dentition are underdeveloped. In addition, it is corroborated that the first tooth generation is absent in Onychodactylus, whereas such monocuspid nonpedicellate tooth generation normally develops at the early larval stages of other caudate amphibians. Since similar patterns of skeleton ontogeny are observed in other caudate groups with different extent of embryonization, it is pro posed that, in different lineages of Urodela, the evolution of ontogeny followed similar pathways and was accompanied by the same changes in skeletogenesis.

The karyotype of a lungless salamander, Onychodactylus fischeri, from Korea was analyzed and compared with that of the Japanese congeneric species, O. japonicus. In both species the diploid karyotype consists of 78 chromosomes, including 6 pairs of large chromosomes, 6 pairs of medium-sized ones, and the remaining 27 pairs of microchromosomes. The chromosome number of O. fischeri, 2n = 78, is, like that of O. japonicus, the largest so far reported in the order Urodela. C-banding showed that constitutive heterochromatin in O.fischeri was mainly in the centromeric regions and near the secondary constrictions of the large chromosomes. AgNO3-bands were located in the secondary constrictions associated with C-band heterochromatin.

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