Cite this paper:
Shuqian ZHANG, Suping ZHANG. Tritonia iocasica sp. nov., a new tritoniid species from a seamount in the tropical Western Pacific (Heterobranchia: Nudibranchia)[J]. Journal of Oceanology and Limnology, 2021, 39(5): 1817-1829

Tritonia iocasica sp. nov., a new tritoniid species from a seamount in the tropical Western Pacific (Heterobranchia: Nudibranchia)

Shuqian ZHANG1,2, Suping ZHANG1,2
1 Laboratory of Marine Organism Taxonomy and Phylogeny, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;
2 Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
During an expedition to a seamount at Caroline Plate in the tropical Western Pacific, a new species of Tritonia was sampled from the upper bathyal zone at depth of 970-1 262 m. This new species, Tritonia iocasica sp. nov., represents the first tritoniid nudibranch known to feed on octocoral of the family Melithaeidae. The species is up to 120 mm in length, pinkish in color; with the rhinophoral sheath divided into several petaliform extensions; veil with about 18 elongate digitiform processes; notal margin with 17-19 pairs of secondary gills; anus located below the 5th and 6th secondary gills, and the genitalia below the 3rd secondary gill on the right side of the body. Based on these external features, T. iocasica sp. nov. can be clearly distinguished from all previously described members of the genus. Phylogenetic analyses of two mitochondrial (COI, 16S rRNA) and a nuclear (H3) genes using Bayesian inference, maximum likelihood, and species delimitation analysis also support the separation of T. iocasica sp. nov. from its congeners.
Key words:    Tritoniidae|Mariana Trench|upper bathyal zone|Melithaeidae   
Received: 2020-10-23   Revised: 2020-12-18
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