Marine annelids in the genus Owenia Delle Chiaje 1844 collected from Chinese coastal waters have long been recorded as O. fusiformis, later O. gomsoni Koh and Bhaud 2001 for that from Qingdao and O. collaris Hartman, 1955 from Hong Kong. But combined morphological and molecular evidence reveal two new species of Owenia from the South China coast. Owenia hongkongensis n. sp. (previously recorded as O. fusiformis) inhabits subtidal and intertidal habitats in Hong Kong, and Owenia hainanensis n. sp. (previously recorded as O. fusiformis) inhabits intertidal habitats in Hainan. They are distinguished from each other and from congeners by branchial crown morphology, chaetal microstructure, and methyl green staining patterns. Mitochondrial genomes and nuclear 18S, 28S and H3 sequences of the two new species were obtained via next-generation sequencing. Phylogenetic analyses based on cox1, 18S, 28S and H3 showed that the species from Hong Kong and Hainan are distinct and they differ from previously sequenced Owenia species from other regions. These discoveries challenge the presumed cosmopolitan distribution of O. fusiformis and emphasize the value of integrating morphometrics and molecular data in the delimitation of Owenia species.
Polychaeta, Oweniidae, Shallow water, Intertidal and subtidal, Integrative taxonomy
