Saturday, May 29, 2021

[Herpetology • 2021] Tylototriton thaiorum • A New Species of the Genus Tylototriton (Caudata: Salamandridae) from Central Vietnam

Tylototriton thaiorum 
 Poyarkov, Nguyen & Arkhipov, 2021

Thai Crocodile Newt  | Cá cóc thái || DOI: 10.47605/tapro.v10i1.244 

We describe a new species of the genus Tylototriton from Pu Hoat Nature Reserve, Nghe An Province, in the northern part of Central Vietnam, based on morphological and molecular evidence. The new species was previously confused with T. vietnamensis from northern Vietnam and T. notialis from Laos. The new species can be distinguished from T. notialis by the absence of orange coloration on posterior end of parotids (vs presence); an indistinct brown coloration on rib nodules (vs bright orange); a broader and slightly rounded head (vs narrower and angular); comparatively shorter limbs (vs longer); slightly fewer number, smaller size and irregular arrangement of rib nodules (vs larger rib nodules arranged in two dorsolateral series). Phylogenetic analysis of the ND2 and 16S rRNA mtDNA genes confirmed the placement of the new species to Clade I of the subgenus Yaotriton, and suggests it is a sister species of T. notialis (p-distance 3.0% in ND2 gene). The range of the new species is restricted to the Pu Hoat Mountain Range and is isolated from the range of T. notialis, which inhabits Northern Annamites (Truong Son) Mountains by the valley of the Ca River, an important biogeographic barrier. The new species is currently known only from the montane forests of Pu Hoat Nature Reserve (at elevations from 700 to 1000 m a.s.l.). We suggest the new species be classified as Endangered (EN) on the IUCN Red List.

 Key words: Tylototriton thaiorum sp. nov., mtDNA genealogy, Pu Hoat Nature Reserve, Ca River

Distribution of Tylototriton notialis sensu stricto (blue) and the new species (red) in Central Vietnam and Laos; inset shows the location of this area on the map of Indochina.
1, Pu Hoat Nature Reserve, Nghe An Province, Vietnam; 2, Nam On River, Nakai-Nam Theun National Protected Area, Khammouan Province, Laos; 3, Mt. Jeung, Khammouan Province, Laos. Stars denote the type localities of T. notialis and the new species.

Phylogenetic tree based on 1665 bp fragments of ND2 and 16S rRNA genes showing T. notialis and Tylototriton thaiorum as sister taxa within the T. asperrimus species complex.

Morphological details of Tylototriton thaiorum holotype (male). Note dark color of paratoids and rib nodules.

Tylototriton thaiorum holotype (male) in life.

Salamandridae Goldfuss, 1820
 Tylototriton Anderson, 1871
Tylototriton thaiorum sp. nov. 

Tylototriton vietnamensis — Böhme et al. 2005 [partim] 
Tylototriton notialis — Nishikawa et al. 2013b [partim], Phimmachak et al. 2015 [partim], Yang et al. 2018 [partim], Than Zaw et al. 2019 [partim], Bernardes et al. 2020 [partim] 

Diagnosis. The new species is assigned to the genus Tylototriton and the subgenus Yaotriton based on the results of the molecular phylogenetic analyses and the following combination of morphological attributes: presence of dorsal granules, dorsolateral bony ridges on head, presence of dorsolateral series of knob-like warts (rib nodules), and absence of quadrate spine (Figs. 3–5). Tylototriton thaiorum sp. nov. is differentiated from all other members of the subgenus Yaotrion by the following combination of morphological characters: medium body size (SVL 59.3–68.6 mm in males); snout obtusely rounded in dorsal view and in lateral profile; skin rough with fine granules; supratemporal bony ridges on head wide, slightly protruding, beginning at the anterior corner of orbit; sagittal ridge on head low and almost indistinct; limbs thin, tips of forelimb and hindlimb overlapping when adpressed along body; vertebral ridge distinct, rough, not segmented; rib nodules 10–14, small, poorly distinct, arranged in two irregular dorsolateral series intermittent with smaller warts; dorsal background coloration dark-brown, ventral coloration greyish brown, limbs blackish; fingers and toe tips, parts of soles and palms, and vent bright orange, orange stripe continuing along the ventral edge of tail to the tail tip.

Etymology. The specific name ―thaiorum is a Latin adjective in the genitive plural (masculine gender), derived from the name of the T[h]ai people who inhabit the montane areas of northern Vietnam and adjacent territories, including the type locality of the new species. The people of Muong Dan Village pointed out to us the breeding habitat of the new species. We suggest the following common names: Thai Crocodile Newt (English), Cá cóc thái (Vietnamese), Taiskiy krokodilovyi triton (Russian).

Nikolay A. Poyarkov, Tan Van Nguyen and Dmitriy V. Arkhipov. 2021. A New Species of the Genus Tylototriton (Amphibia: Caudata: Salamandridae) from Central Vietnam. TAPROBANICA. 10(1); 4–22. DOI: 10.47605/tapro.v10i1.244