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| Chaetoderma shenloong Chen, Liu, Gu, Qiu & Sun, 2024 |
Abstract
Caudofoveata is a class of worm-like molluscs (aplacophorans) that typically have an infaunal lifestyle, burrowing in soft bottoms in a wide range of marine habitats from shallow to deep waters. Here, we describe a very large new species of caudofoveate from South China Sea methane seeps growing up to 154 mm in length: Chaetoderma shenloong sp. nov. It is the first caudofoveate to be named from a chemosynthetic ecosystem and the first aplacophoran mollusc associated with seeps. Our new species stands out from other Pacific Chaetoderma species by its large size, a wide body relative to its length, a barely sclerotised radula, and the presence of isosceles-triangular sclerites. Phylogenetic reconstruction using the mitochondrial cytochrome c oxidase subunit I (COI) gene placed it within a paraphyletic clade comprising Chaetodermatidae and Limifossoridae, in line with a previous phylogenetic analysis. This also revealed that C. shenloong sp. nov. is conspecific with a Chaetoderma sp. whose whole genome was recently sequenced and assembled but remained undescribed until now. The most closely related species with an available COI sequence was C. felderi, the largest caudofoveate species recorded. Our discovery suggests caudofoveates may be present in other seeps globally but so far neglected; a potential example is C. felderi from the Gulf of Mexico, where seeps are abundant but whose exact habitat remains unclear.
Key Words: Aplacophora, Caudofoveata, chemosynthetic, F site, Haima, hydrocarbon seep, Jiaolong Ridge, new species
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| Chaetoderma shenloong sp. nov., photographs of preserved-type specimens. A. Holotype (TMBC031015), lowercase Roman numerals indicate the six body regions from where sclerites were examined: i) peribuccal region, ii) foregut region, iii) midgut region, iv) midgut sac region, v) prepallial region, and vi) pallial region; B. Holotype (TMBC031015), enlarged dorsal view of the prepallial and pallial regions; C. Paratype 1 (TMBC031016); D. Paratype 2 (TMBC031017). Arrowheads indicate the anterior end of the animal. |
Chaetoderma shenloong sp. nov.
Chong Chen, Xu Liu, Xinyu Gu, Jian-Wen Qiu and Jin Sun. 2024. Integrative Taxonomy of A New giant Deep-sea Caudofoveate from South China Sea cold seeps. Zoosystematics and Evolution 100(3): 841-850. DOI: doi.org/10.3897/zse.100.125409
