Stirring the Deep, Disentangling the Complexity: Report on the Third Species of Thermochiton (Mollusca: Polyplacophora) From Haima Cold Seeps

This study documents a new deep-sea chiton from the Haima cold seeps. Thermochiton xui . nov. is third species of genus and first occurrence this in South China Sea. identified by its morphological characteristics molecular sequence reported for time. The placement determined phylogenetic tree Ischnochitonidae Maximum Likelihood (ML) Bayesian inference (BI) methods, based on sequences mitochondrial cytochrome c oxidase subunit I (COI), 16S ribosomal DNA (16S), nuclear 28S (28S) gene regions. evolutionary analysis with an uncorrelated relaxed clock approach indicated that estimated to have diverged most closely related shallow-water ischnochitonid taxa 5.10–10.07 million years ago Late Miocene. A regional ocean general circulation model was used estimate potential dispersal ability three Thermochiton. Because it highly unlikely one spread between northwest southwest Pacific localities which has been found date, we propose ‘stepping-stone’ habitats and/or ‘bridge species’ were involved evolution these cold-seep endemic chitons. ZooBank Life Science Identifier (LSID) publication is: urn:lsid:zoobank.org:pub:AD93E4BC-2977-405E-B681-D956C5C66D83. And ISID sp. urn:lsid:zoobank.org:act:0C75D2E3-F30E-4970-9BC2-3363B397720C.