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| Chaetoderma naga Liu, Chen, Gu & Sun, 2025 |
ABSTRACT
Deep-sea chemosynthetic ecosystems such as hydrothermal vents and hydrocarbon seeps are home to numerous endemic species. Despite decades of exploration, the diversity of minor animal groups such as aplacophoran molluscs in these systems remain understudied. The recent discovery of Chaetoderma shenloong, a giant caudofoveate from Haima cold seep in the South China Sea, marked the first aplacophoran from cold seeps and the first caudofoveate from chemosynthetic systems overall. Here, we report another giant caudofoveate species from Haima seep – Chaetoderma naga sp. nov. This new species is morphologically closest to C. shenloong, but differ significantly in spicule morphology where the distribution of isosceles-triangle shaped spicules differ and that the needle-like spicules are much longer and thicker in C. shenloong. Molecular phylogenetic reconstruction based on the mitochondrial cytochrome c oxidase subunit I (COI) gene recovered C. naga n. sp. as sister to C. shenloong among those with data available, with a K2P genetic distance of 17% supporting the status of C. naga n. sp. as a separate species. Our discovery highlights the presence of overlooked biodiversity within sediments of chemosynthetic ecosystems and reinforces the possibility of a high caudofoveate diversity in such environments.
KEYWORDS: Chaetoderma, chemosynthetic, Aplacophora, Caudofoveata, new species, hydrocarbon seep
Chaetoderma naga sp. nov.
Xu Liu, Chong Chen, Xinyu Gu and Jin Sun. 2025. A Second Species of Giant caudofoveate Worm-mollusc from Haima cold seep in the South China Sea. Molluscan Research. DOI: doi.org/10.1080/13235818.2025.2566524 [10 Oct 2025]
