Integrative taxonomy reveals three new taxa within the Tylototriton asperrimus complex (Caudata, Salamandridae) from Vietnam

Abstract

The Tylototriton asperrimus complex from northern Vietnam is reviewed based on morphological comparisons and analysis of the mitochondrial marker NADH dehydrogenase subunit 2 (ND2). Based on molecular divergences, which were revealed to be higher than in other congeners, in concert with morphological differences, two new species and one subspecies are described herein: Tylototriton pasmansisp. nov. differs from T. asperrimussensu stricto by 3.2 to 3.6 % genetic divergence and a combination of distinct morphological characters, such as head slightly longer than wide, distinct mid-dorsal ridge, relatively wide distance between the eyes, tips of fingers reaching the eye when foreleg is laid forward, labial and gular folds present, central belly skin with tubercles shaped like transverse wrinkles and distinct, pointy to round rib nodules. The population of T. pasmansisp. nov. consists of two subclades, the nominotypic one occurring on the eastern side of the Da River (or Black River, including Hoa Binh and Phu Tho provinces), and another occurring on the western side (including Son La and Thanh Hoa provinces). These two subclades differ by 2.5 to 3.1 % genetic divergence and distinct morphological characters. The western subclade is herein described as Tylototriton pasmansi obstissp. nov., which differs from the nominotypic form by a wider head, longer and narrower snout, shorter femur length, and an overall less granulose skin, without an increased concentration of warts on the body sides. A second new species, Tylototriton sparreboomisp. nov. is described from Lai Chau Province. It differs from T. asperrimussensu stricto by 4.1 to 4.2 % and from Tylototriton pasmansisp. nov. by 3.6 to 4.5 % genetic divergences as well as by a combination of distinct morphological characters, such as head longer than wide, tips of fingers reaching nostril when foreleg adpressed along head, rib nodules distinct, round and relatively enlarged, and wide distance between the eyes.

A NEW SPECIES OF THE GENUS Tylototriton (AMPHIBIA, CAUDATA, SALAMANDRIDAE) FROM CENTRAL VIETNAM

“…The salamandrid genus Tylototriton Anderson, 1871 (colloquially known as crocodile newts) currently includes 31 recognized species, inhabiting montane forest areas throughout the Asian monsoon climate zone from eastern Himalaya, southern and central China including Hainan Island, to northern Indochina including northern Vietnam, Laos, northern Thailand, and Myanmar (Wang et al 2018, Bernardes et al 2020, Frost 2021). The genus is traditionally partitioned into two subgenera: Tylototriton sensu stricto is characterized by the presence of orange spots on the head, dorsum, tail, or sides TAPROBANICA VOL.…”

“…Several recent phylogenetic studies also demonstrated that our knowledge on taxonomic diversity of the genus Tylototriton is still far from complete, indicating the presence of numerous undescribed morphologically cryptic lineages, which actually might represent independent species (Wang et al 2018, Than Zaw et al 2019. The amount of undescribed diversity appears to be especially high in the T. asperrimus group of the subgenus Yaotriton (Bernardes et al 2020, Li et al 2020. The number of species of Tylototriton in Vietnam is high, with seven species of this genus having been recorded so far for the country, namely T. anguliceps Le, Nguyen, Nishikawa et al 2015, T. notialis Stuart, Phimmachak, Sivongxay & Robichaud, 2010, T. pasmansi Bernardes, Le, Nguyen et al, 2020, T. cf.…”

“…The number of species of Tylototriton in Vietnam is high, with seven species of this genus having been recorded so far for the country, namely T. anguliceps Le, Nguyen, Nishikawa et al 2015, T. notialis Stuart, Phimmachak, Sivongxay & Robichaud, 2010, T. pasmansi Bernardes, Le, Nguyen et al, 2020, T. cf. pulcherrimus Hou, Zhang, Li & Lu, 2012, T. sparreboomi Bernardes, Le, Nguyen et al, 2020, T. vietnamensis Böhme, Schöttler, Nguyen & Köhler, 2005, and T. ziegleri Nishikawa, Matsui & Nguyen, 2013a(Böhme et al 2005, Nishikawa et al 2013b, Le et al 2015, Fei & Ye 2016, Bernardes et al 2020. It is noteworthy that six of the seven Tylototriton species recorded from Vietnam were described during the last ten years.…”

“…Three other species, namely T. asperrimus Unterstein, 1930 (presently restricted to southeastern China), T. verrucosus Anderson, 1871 (presently restricted to Yunnan Province of China, northern Myanmar and Thailand), and T. shanjing Nussbaum, Brodie & Yang, 1995 (presently restricted to Yunnan Province of China) also have been reported from Vietnam (Nguyen et al 2009, Hernandez 2016). However, recent phylogenetic studies suggest that these records were likely based on misidentifications of T. pasmansi or T. sparreboomi, and T. anguliceps complex members, respectively (see Le et al 2015, Bernardes et al 2020.…”

A morphological and molecular review of the genus Goniurosaurus, including an identification key

“…Indeed, by employing a molecular dating method, Liang et al (2018) estimated that the latest speciation events among tiger geckos took place approximately 2.8-2.9 Ma, in the late Pliocene, between G. yamashinae-G. orientalis, and G. huuliensis-G. luii. It is likely that the global warming during the Pliocene promoted the diversification in the genus, as also reported in the crocodile newts (genus Tylototriton Anderson, 1871) in Asia (Bernardes et al 2020). Thus, the genus Goniurosaurus might offer a unique opportunity to investigate mechanisms of speciation and evolutionary adaptation, that are expected to highly correlate with a pre-dominantly allopatric mode of diversification.…”