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Crocodile newts (Echinotriton and Tylototriton) are emblematic of the biodiversity of South-East Asia. In this study, we provide an account of their evolution, diversity and phylogeography based on mitochondrial (16.2 kb) and nuclear sequences (3.2 kb), combining barcoding data from nearly 1200 specimens collected over ~180 localities, representative of all lineages known to date. While phylogenies of nuclear data lacked resolution, the mitochondrial tree showed dynamic allopatric speciation that followed climate cooling during the last 10 million years, a pattern shared with many other tropical and subtropical amphibians. In crocodile newts, this implies weak dispersal and local adaptation as contributing factors of isolation, and was accompanied by macro- and micro-evolutionary changes in reproductive behaviours. Specifically, our resolved phylogeny of Tylototriton allowed the tracing of a major shift from conserved habits of terrestrial clutch-spawning towards more plastic strategies involving both aquatic and land spawning of single eggs. Using this framework, we then revised the taxonomy of crocodile newts by describing a new subgenus and two new species. Our study provides a basis to guide future phylogeographic, speciation and conservation research on these iconic amphibians. [ABSTRACT FROM AUTHOR]

The diversity of the vertebrate cranial shape of phylogenetically related taxa allows conclusions on ecology and life history. As pleurodeline newts (the genera Echinotriton, Pleurodeles and Tylototriton) have polymorphic reproductive modes, they are highly suitable for following cranial shape evolution in relation to reproduction and environment. We investigated interspecific differences externally and differences in the cranial shape of pleurodeline newts via two‐dimensional geometric morphometrics. Our analyses also included the closely related but extinct genus Chelotriton to better follow the evolutionary history of cranial shape. Pleurodeles was morphologically distinct in relation to other phylogenetically basal salamanders. The subgenera within Tylototriton (Tylototriton and Yaotriton) were well separated in morphospace, whereas Echinotriton resembled the subgenus Yaotriton more than Tylototriton. Oviposition site choice correlated with phylogeny and morphology. Only the mating mode, with a random distribution along the phylogenetic tree, separated crocodile newts into two morphologically distinct groups. Extinct Chelotriton likely represented several species and were morphologically and ecologically more similar to Echinotriton and Yaotriton than to Tylototriton subgenera. Our data also provide the first comprehensive morphological support for the molecular phylogeny of pleurodeline newts. [ABSTRACT FROM AUTHOR]

We describe a new species of the genus Tylototriton from Ingyin Taung Mt., Mohnyin Township, Kachin State, Myanmar, based on morphological and molecular evidence. The new species is assigned to the subgenus Tylototriton s. str. and is clearly distinct from all known congeners by the following characters: medium body size; thin, long tail, lacking lateral grooves; rough skin; truncate snout; wide, protruding supratemporal bony ridges on head, beginning at anterior corner of orbit; weak, almost indistinct sagittal ridge; long, thin limbs, broadly overlapping when adpressed along body; distinct, wide, non-segmented vertebral ridge; 13 or 14 rib nodules; brown to darkbrown background coloration with dull orange-brown to yellowish-brown markings on labial regions, parotoids, rib nodules, whole limbs, vent, and ventral tail ridge. We also briefly discuss biogeography and species diversity of the genus Tylototriton in Myanmar. [ABSTRACT FROM AUTHOR]

The Taliang crocodile newt, Liangshantriton taliangensis, which is endemic to south-western China, is a rare salamandrid species with a distinct evolutionary history. Using combined field observations and captive experiments, we studied the courtship behaviour and male sexual interference of this species and composed a complete ethogram of its courtship behaviour. Unlike previous reports on sperm transfer, male L. taliangensis did not deposit spermatophores during ventral amplexus and females did not pick up sperm masses in this courtship phase. Sperm transfer was only performed during arm-hooking pin-wheel circling, which distinguishes L. taliangensis from Tylototriton species and supports the validity of genus Liangshantriton. Whether L. taliangensis shows bimodality in sperm transfer needs to be explored in additional populations. In the presence of sexual competitors, male L. taliangensis adjusted the duration of their behaviour. We found that males with longer snout-vent length, heavier mass, and higher tailfins may have an advantage in intrasexual competition. [ABSTRACT FROM AUTHOR]

Global climatic transitions and Tibetan Plateau uplifts are hypothesized to have profoundly impacted biodiversity in southeastern Asia. To further test the hypotheses related to the impacts of these incidents, we investigated the diversification patterns of the newt genus Tylototriton sensu lato, distributed across the mountain ranges of southeastern Asia. Gene-tree and species-tree analyses of two mitochondrial genes and two nuclear genes revealed five major clades in the genus, and suggested several cryptic species. Dating estimates suggested that the genus originated in the early-tomiddle Miocene. Under different species delimitating scenarios, diversification analyses with birth-death likelihood tests indicated that the genus held a higher diversification rate in the late Miocene-to-Pliocene era than that in the Pleistocene. Ancestral area reconstructions indicated that the genus originated from the northern Indochina Peninsula. Accordingly, we hypothesized that the Miocene Climatic Transition triggered the diversification of the genus, and the reinforcement of East Asian monsoons associated with the stepwise uplifts of the Tibetan Plateau promoted the radiation of the genus in southeastern Asia during the Miocene-to-Pliocene period. Quaternary glacial cycles likely had limited effects on speciation events in the genus, but mainly had contributions on their intraspecific differentiations. [ABSTRACT FROM AUTHOR]

Almost nothing is known on the ecology and natural history of Tylototriton (Knobby Newts) in Laos. Here, a population of the newly described T. podichthys was intensively studied in a 55,800 m² area in Xiengkhouang Province, Laos, from June 2012-July 2013. Mark-recapture methods estimated 301 individuals of T. podichthys at the study site. Newts were abundant during the breeding season (June-July), with a maximum density of 8.75 newts in 100 m2 of stream. The sex ratio of adult males and females was almost equal and did not differ throughout the year. The population was sexually dimorphic, with females having larger and heavier bodies than males, and different cloacal morphologies during the breeding season. Males, females and immature newts (efts) used a variety of habitat and microhabitat types. Adult newts occupied a stream only during a brief breeding period, but otherwise were primarily terrestrial. The breeding season began in the early rainy season during June-July, and efts emerged from the stream during the dry, cold season beginning in December. Diet was studied by stomach-flushing methods, and consisted primarily of terrestrial invertebrates, especially woodlice (Ligiidae), earthworms (Haplotaxida) and pillbugs (Armadillidae). Unlike in many other newts, conspecific oophagy was not observed. Diet composition, number of prey consumed, and volume of prey consumed did not differ among adult males, adult females or efts. [ABSTRACT FROM AUTHOR]

We assessed taxonomic relationship of Tylototriton daweishanensis Zhao, Rao, Liu, Li and Yuan, 2012 and T. yangi Hou, Li and Lu, 2012 using mitochondrial DNA sequence data and found them to be as closely related as to be regarded as conspecific. This result, together with available morphological information, strongly indicates that T. daweishanensis is a junior synonym of T. yangi. [ABSTRACT FROM AUTHOR]

We describe a new species of Tylototriton from northwestern Vietnam and northern Thailand based on morphological and molecular evidence. Tylototriton anguliceps sp. nov. is distinguishable from all the other congeners by the bright to dark orange markings on the head, body, and tail, prominent dorsal and dorsolateral ridges (crests) on the head, skeletal connection between maxillary and pterygoid, and unique mitochondrial and nuclear DNA sequences. Our molecular data show that the new species is nested within the clade comprising T. uyenoi, T. shanjing, T. verrucosus, and T. yangi. The new species is expected to be recorded from other countries in the Indochina region such as southern China, western Myanmar and northern Laos in the future. [ABSTRACT FROM AUTHOR]

Anderson's crocodile newt (Echinotriton andersoni) is distributed in the Central Ryukyu Islands of southern Japan, but environmental degradation and illegal collection over the last several decades have devastated the local populations. It has therefore been listed as a class B1 endangered species in the IUCN Red List, indicating that it is at high risk of extinction in the wild. The species is also protected by law in both Okinawa and Kagoshima prefectures. An artificial insemination technique using hormonal injections could not be applied to the breeding of this species in the laboratory. In this study we naturally bred the species, and tested a laboratory farming technique using several male and female E. andersoni pairs collected from Okinawa, Amami, and Tokunoshima Islands and subsequently maintained in near-biotopic breeding cages. Among 378 eggs derived from 17 females, 319 (84.4%) became normal tailbud embryos, 274 (72.5%) hatched normally, 213 (56.3%) metamorphosed normally, and 141 (37.3%) became normal two-month-old newts; in addition, 77 one- to three-year-old Tokunoshima newts and 32 Amami larvae are currently still growing normally. Over the last five breeding seasons, eggs were laid in-cage on slopes near the waterfront. Larvae were raised in nets maintained in a temperature-controlled water bath at 20 °C and fed live Tubifex. Metamorphosed newts were transferred to plastic containers containing wet sponges kept in a temperature-controlled incubator at 22.5 °C and fed a cricket diet to promote healthy growth. This is the first published report of successfully propagating an endangered species by using breeding cages in a laboratory setting for captive breeding. Our findings on the natural breeding and raising of larvae and adults are useful in breeding this endangered species and can be applied to the preservation of other similarly wild and endangered species such as E. chinhaiensis. [ABSTRACT FROM AUTHOR]

The habitat preferences of the endemic Vietnam Crocodile Newt,Tylototriton vietnamensiswere investigated on two scales: (1) at Yen Tu Nature Reserve, Bac Giang Province, Vietnam, while compiling information about pond occupancy and developing a qualitative comparison among breeding sites and (2) by developing a Species Distribution Model based on climate and land cover data identifying further suitable habitats in northern Vietnam. A factor analysis followed by a multiple linear regression showed 94% support for our occupancy ranking model. Our results suggest thatT. vietnamensispreferentially inhabits small pools with long hydroperiod and pH above 4.3. Suitable areas for the species have higher incidence in northern regions, where undisturbed vegetation and temperature-related variables seem to make greater contributions. Additionally, these potentially suitable areas are strongly fragmented and only a few are under IUCN protection, increasing their vulnerability towards further degradation. [ABSTRACT FROM AUTHOR]

Factors that determine the genetic structure of species in southwestern China remain largely unknown. In this study, phylogeography and demography of Tylototriton shanjing was investigated from a mitochondrial perspective to address the role of the Quaternary ice ages in shaping phylogeographic history and genetic diversity of Yunnan. A total of 146 individuals from 19 populations across the entire range of the species were collected. We detected four maternal phylogenetic lineages corresponding to four population groups, and found that major glaciation events during the Pleistocene have triggered the intra-specific divergence. Coalescent simulations indicated that the populations retreated to different refugia located in southern Yunnan, northwestern Yunnan, the border region of western Yunnan with Myanmar, and middle-western Yunnan, respectively, during previous glacial periods in the Pleistocene, and these four refugia were not retained during the Last Glacial Maximum. Population expansions occurred during the last inter-glaciation, during which ice core and pollen data indicated that the temperature and precipitation gradually increased, and declines of population sizes started after the beginning of the Last Glacial Maximum when the climate became cooler and dryer. The paleo-drainage system had no contribution to the current genetic structure and the rivers were not dispersal barriers for this salamander. [ABSTRACT FROM AUTHOR]

A new species of the salamandrid genus Tylototriton is described from Ha Giang and Cao Bang provinces, northern Vietnam, based on molecular and morphological data. The new species differs morphologically from all known congeners in the combination of blackish body coloration; medium-sized body; distinctly rough skin; tubercular vertebral ridge; knob-like rib nodules; large eye; and low, narrow tail. The distribution pattern of species of Tylototriton in Vietnam is briefly discussed. [ABSTRACT FROM AUTHOR]

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Tylototriton anhuiensis (Salamandridae, Urodela), collected from Yaoluoping Nature Reserve, was identified as a new species. The complete mitogenome sequence of T. anhuiensis is 16,259 by in length, including 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and D-loop region. The base composition of the mitogenome was 33.6%A, 26.3% C, 14.5% G, and 25.6% T. The ND6 subunit gene and eight tRNA genes were encoded on the L-strand, the others were encoded on the H-strand. [ABSTRACT FROM AUTHOR]

In this paper, the complete 16,725 bp nucleotide sequence of the mitochondrial genome was determined for theTylototriton kweichowensis(Caudata:Salamandridae). It contains 37 genes (13 protein-coding genes, 2 rRNA genes and 22 tRNA genes) and a non-coding region (D-loop). Overall base composition of the complete mitochondrial DNA is A (33.8%), G (14.4%), C (26.2%), and T (25.6%), so the percentage of A and T (59.4%) is higher than G and C (40.6%). All the genes inT. kweichowensisare distributed on the H-strand, except for theND6subunit gene and eight tRNA genes which are encoded on the L-strand. [ABSTRACT FROM PUBLISHER]

The entire mitogenome ofTylototriton kweichowensisis 16 727 bp in length. It consists of 13 protein-coding genes (PCGS), 2 ribosomal RNA genes (rRNA), 22 transfer RNA genes (tRNA), and 1 control region (CR). Except for ND6 subunit and 8 tRNA genes are distributed on the L-strand, all the other PCGs and tRNA genes are located on the H-strand. “ATG” and “GTG” are the start codons of the PCGs, “TAA”, “AGA”, “TA–” and “T––” are the stop codons. Most of the tRNA genes can be folded into typical clover-leaf secondary structure. The genome ofT. kweichowensishas two repeat sequences in the cob-noncoding region. Mitogenomic phylogenetic analysis (NJ tree) robustly resolved the genus-level relationship among the three generaTylototriton, Echinotriton, andPleurodeles, and which is congruent with the previous molecular phylogeny results. [ABSTRACT FROM AUTHOR]

The complete mitogenome ofTylototriton shanjingis 16,661 bp in length with GenBank accession number KR154461, which contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNA), 2 ribosomal RNA genes (rRNA), and 1 control region (CR). The overall base composition of this mitogenome is biased toward AT content at 59.45%. Most of the PCGs and tRNA genes are located on the H-strand, except for ND6 subunit gene and eight tRNA genes, which were distributed on the L-strand. The PCGs used “ATG” and “GTG” as the start codons, while “TAA”, “TAG”, “AGA”, and “T–” are used as stop codons. Almost all tRNA genes were folded into typical cloverleaf secondary structures. TheT. shanjinggenome had two tandem repeat sequences in the cob-noncoding region. The mitogenomic phylogenetic analyses shows that the generaEchinotriton and Tylototritonwere clustered into a strong supported monophyletic clade, which is a sister clade to the genusPleurodeles, this confirms the previous phylogenetic results. [ABSTRACT FROM AUTHOR]

Tylototriton taliangensiswas listed as a Near Threatened amphibian in IUCN red list. In this study, we sequenced the complete mitochondrial (mt) genome of this species (GenBank: KP979646) and found it contains 16,265 base pairs, which encode 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNA), 2 ribosomal RNA genes (rRNA) and 1 control region (CR). We also found that almost all PCGs and tRNA genes are located on the H-strand, except for ND6 subunit gene and eight tRNA genes, which were distributed on the L-strand. The PCGs used “ATG” and “GTG” as the start codon, while used four types of stop codons. Almost all tRNA genes were folded into typical cloverleaf secondary structures. The L-strand replication origin (OL) and a non-coding region were also found. The new mitogenomic phylogenetic tree confirms the reciprocally monophyly of the genusTylototriton, EchinotritonandPleurodeleswith high bootstrap value. The present study will provide information for future studies on the conservation genetics and phylogeny of this species and its relatives. [ABSTRACT FROM AUTHOR]