Recent Progress in Taxonomic Studies, Biogeographic Analysis, and Revised Checklist of Amphibians in Indochina

Abstract

The Indochinese Peninsula is recognized as one of the key global biodiversity hotspots. The amphibian fauna of Indochina (including Vietnam, Laos, Cambodia and Thailand) is one of the richest in the world. About 60% of the known species were described within the last 20 years. We review the literature and our data to assess all recent discoveries and taxonomic changes and compile the first annotated checklist of the amphibian fauna of Indochina since the middle of the 20th century, including updated faunal lists for Vietnam and Thailand. Amphibian checklists for Laos and Cambodia are published for the first time. For each species we provide the following information: scientific name; recommended common name in English; information on type specimens; type locality; data on its distribution within Indochina and beyond; IUCN conservation status; taxonomic comment and the most important references. We review the distribution of each species across the 23 biogeographic subregions of Indochina, estimate the similarity among the regional faunas and evaluate their species richness and endemism. In total we record 423 amphibian species belonging to three orders, 11 families and 71 genera; 199 species (47%) are endemic to Indochina. Comprising 270 known species, the amphibian fauna of Vietnam is the richest (98 endemics, 36.3%), followed by Thailand with 194 species (29 endemics, 14.9%), Laos with 121 species (13 endemics, 10.7%), and Cambodia with 72 species (6 endemics, 8.3%). A cluster analysis of faunal similarity between the subregions shows two major assemblages, divided by the Isthmus of Kra. Within the northern mainland portion of Indochina three clusters can be distinguished: (1) northeastern and northwestern uplands of Vietnam and northern Laos; (2) Northern, Central, and Southern Annamites, the Bolaven Plateau, and central-south Vietnam lowlands; (3) western Indochinese subregions. We identify the Northeast and Northwest Uplands of Vietnam, the Northern, Central and Southern Annamites, the Cardamom Mountains, the mountains of Northeast Thailand, Northern Tenasserim and southern Peninsular Thailand as nine major centers of diversity and endemism of Indochinese amphibians. The analysis of amphibian distribution patterns across Indochina suggests the presence of 14 chorotypes grouped in five major range types. Our results underline the role of Indochina as a key area for amphibian diversity and conservation. Among 423 species of Indochinese amphibians, 152 species (35.9%) were considered as data deficient (DD) or were not evaluated (NE) according to the IUCN Red List criteria; while 76 species (18.0%) were considered vulnerable (VU), endangered (EN) or critically endangered (CR), 20 species (4.7%) were considered to be near threatened (NT), and 175 species (41.4%) to be of the least concern (LC). Our study thus has implications for further conservation efforts on regional and global levels, as well as for understanding the biogeographic patterns of amphibian richness and endemism in Asia.

Figure 1 from: Pomchote P, Peerachidacho P, Hernandez A, Sapewisut P, Khonsue W, Thammachoti P, Nishikawa K (2021) A new species of the genus Tylototriton (Urodela, Salamandridae) from western Thailand. ZooKeys 1072: 83-105. https://doi.org/10.3897/zookeys.1072.75320

“…Geographic isolation may limit gene flow and promote genetic differentiation among populations which can result in the formation of new species (Eckert et al 2008;Qian et al 2017). Tak Province is located in the Northwest Thai (Dawna) Uplands of Indochina (Poyarkov et al 2021b), which consists of several high-mountain areas in the three major mountain ranges: (i) Thanon Thong Chai and (ii) Daen Lao Ranges in northernmost Tak Province, and (iii) Dawna Range in most areas of Tak Province. The Thanon Thong Chai Range has T. uyenoi in Namtok Mae Surin NP, Mae Hong Son Province (Pomchote et al 2020a).…”

A new species of the genus Tylototriton (Urodela, Salamandridae) from western Thailand

“…Geographic isolation may limit gene flow and promote genetic differentiation among populations which can result in the formation of new species ( Eckert et al 2008 ; Qian et al 2017 ). Tak Province is located in the Northwest Thai (Dawna) Uplands of Indochina ( Poyarkov et al 2021b ), which consists of several high-mountain areas in the three major mountain ranges: (i) Thanon Thong Chai and (ii) Daen Lao Ranges in northernmost Tak Province, and (iii) Dawna Range in most areas of Tak Province. The Thanon Thong Chai Range has T. uyenoi in Namtok Mae Surin NP , Mae Hong Son Province ( Pomchote et al 2020a ).…”

Interspecific amplexus between a male Yang’s Frilled Treefrog, Kurixalus yangi Yu, Hui, Rao, and Yang 2018, and a female Brauer’s Brown Treefrog, Polypedates braueri (Vogt 1911), with recommendations for English common names

“…The native range of Polypedates braueri, a rhacophorid originally described from Taiwan, extends from tropical and subtropical China and Taiwan through Vietnam, probably Laos, and Myanmar to Mizoram, India (Lalronunga et al 2020;Rahman et al 2020;Frost 2021). All of the English common names applied to this species were coined prior to the resurrection of this taxon from the synonymy of P. megacephalus or imply that the species is restricted to Taiwan (Frost 2021;Poyarkov et al 2021); we therefore propose Brauer's Brown Treefrog as the common name for this species. Herein we report, to the best of our knowledge, the first case of interspecific amplexus between an adult male Kurixalus yangi and an adult female Polypedates braueri.…”