The first record of the Dendrodoris arborescens (Collingwood, 1881) (Gastropoda, Nudibranchia) in the Yellow Sea (Dalian, Liaoning, China).

Background: The nudibranch genus Dendrodoris Ehrenberg, 1831 (Mollusca, Gastropoda, Nudibranchia, Dendrodorididae) comprises a group of marine gastropods commonly known as "doris"nudibranchs. Members of this genus are characterised by their soft, flattened bodies, lack of radular teeth and reliance on sponge prey for nutrition. D. arborescens (Collingwood, 1881) originally was described from the Haitan Strait in the East China Sea, subsequent records having been reported from South Korea, Japan, Australia and the Philippines.

New information: This study documents the first record of the dendrodorid nudibranch Dendrodoris arborescens (Collingwood, 1881) from the northern Yellow Sea, China. This study is based on twenty specimens collected from the lower intertidal zone at Heishijiao, Dalian, China (38.864987N, 121.548425E) between December 2023 and September 2024.The species identification was confirmed through morphological examination and molecular analysis of the COI gene sequence. This discovery extends the known northern distributional limit of the species by approximately 800 km from Jeju Island, South Korea and represents the first record of both the species and the genus Dendrodoris Ehrenberg, 1831 in northern Chinese waters. The potential role of the Kuroshio Current extension in facilitating long-distance dispersal of planktotrophic larvae is discussed, along with the significance of this finding for updating the marine biodiversity inventory of northern Chinese waters.