A new species of Tylototriton recorded in Phia Oac - Phia Den National Park

The international scientific journal Alytes recently published the discovery of a new Tylototriton species in Cao Bang Province, Vietnam. This species was described by scientists from the Joint Vietnam-Russia Tropical Science and Technology Research Center and their collaborators. This is the 10^th recorded species of Tylototriton in Vietnam and the 42^nd worldwide. The newly identified species has been named the Cao Bang crocodile newt - Tylototriton koliaensis. This name highlights both its geographical origin and the significance of its habitat within Phia Oac - Phia Den National Park, Cao Bang Province.

Scientists recorded Tylototriton koliaensis at elevations ranging from 1,000 to 1,400 meters above sea level, primarily within the Kolia Pass and Kolia Organic Farm areas.

Using an integrative approach combining morphological and anatomical assessments (including jaw and skull structure) with molecular analyses (mitochondrial DNA, multilocus genomic loci), researchers have confirmed that Tylototriton koliaensis is distinct from all previously described Tylototriton species in Vietnam and globally.

The Cao Bang crocodile newt features a black dorsal surface, a dark gray-black ventral region, and black limbs. The fingertips, toe tips, and portions of the palms and soles exhibit bright orange coloration. A distinct orange stripe extends along the lower edge of the tail to its tip. Unlike some related species, Tylototriton koliaensis lacks bright orange markings on the parotoid glands and lateral tubercles.

Male individuals range from 56.0 to 61.4 mm in body length, while females measure between 70.8 and 73.0 mm. The snout appears flat when viewed from above and rounded in lateral profile. The head's length and width are nearly equal. Skin folds are thin. The skin is rough with fine tubercles along the sides, which gradually decrease in size toward the back. The dorsal ridge on the head is weakly developed, while the vertebral ridge is well-defined. Along the flanks, 10-12 irregularly arranged tubercles intersperse with smaller ones.

The Cao Bang crocodile newt breeds in the summer, from April to July. During this period, individuals are found in slow-flowing stream sections and shallow pools (30-50 cm in depth). The tadpoles have relatively broad heads, with the interorbital distance exceeding the internarial distance. The tail is pointed, the tail fin is taller than the abdominal fin, and the tail is shorter than the body. Throughout development, tadpoles remain dark in color, except for yellowish fingertips and abdominal fins. During winter, adult newts retreat beneath rocks and into crevices, adopting a terrestrial phase.

The Cao Bang crocodile newt (Tylototriton koliaensis)

A - Male individual, B - Female individual (Photo: Nikolay A. Poyarkov).

Distribution area of the Cao Bang crocodile newt

A - Overview image, B - Image of the recorded species location (Photo: Le Xuan Son).

Nowadays, newts of the genus Tylototriton are among the most threatened amphibians globally. Consequently, all species within this genus are listed under the Appendices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). In Vietnam, Tylototriton species are included in Appendix IIB of the Government Decree No. 84/2021/NĐ-CP, which governs the management of endangered, precious, and rare forest plants and animals while ensuring compliance with international threatened plants and animals trade regulations.

According to the latest IUCN Red List update (February 2025), 22 Tylototriton species (belonging to the genus Tylototriton) are classified as Vulnerable (VU) to Critically Endangered (CR). Preliminary assessments indicate that Tylototriton koliaensis is distributed across approximately 664 hectares within Phia Oac - Phia Den National Park, a region historically impacted by human activities. However, in recent decades, local authorities, residents, and park officials have made concerted efforts to protect and restore the forest, including reforestation initiatives using native tree species. Given the heightened vulnerability of Tylototriton species to environmental changes and the broader impacts of global climate change, scientists have recommended that Tylototriton koliaensis be classified as Endangered (EN) on the IUCN Red List.

Protecting this species and its habitat will be crucial to maintaining and enhancing the biodiversity of Phia Oac - Phia Den National Park. Therefore, further research is needed to comprehensively understand the biological and ecological traits of Tylototriton koliaensis, refine its distribution range within and beyond the National Park, and establish appropriate conservation strategies.

Authors: Nguyen Vu Anh, Le Xuan Son, Nguyen Xuan Dac (Institute of Tropical Ecology/VRTC)

Ngoc Nguyen translated

Source: Nikolay A. Poyarkov, Tan Van Nguyen, Son Xuan Le, Dac Xuan Le, Dmitriy V. Arkhipov, Vladislav A. Gorin, Axel Hernandez & Christophe Dufresnes. Multiple lines of evidence for a new cryptic species of Tylototriton (Amphibia, Salamandridae) from northern Vietnam. Alytes, 11/2024, 41 (1-4):56-98.