Occurrence and Identification of the Hydromedusae Sarsia tubulosa (Hydrozoa, Corynidae) in Chinese Coastal Waters

Sarsia tubulosa (M. Sars, 1835) belongs to the family Corynidae, and is mainly distributed in coastal boreal and arctic waters. During regular zooplankton sampling in a coastal artificial lake (Lake Fenghuang) near the northern Yellow Sea (36°55′N, 122°24′E) in May 2015, we found high densities of Sarsia sp. in the zooplankton samples. The mean density of the medusae was 50 ± 40 individuals m −3 (mean ± SD). These specimens were characterized by a long tube-like manubrium and were consistent with previous descriptions of S. tubulosa . Furthermore, a molecular phylogenetic analysis of the mitochondrial cytochrome c oxidase I subunit gene fragments revealed that these individuals clustered with S. tubulosa . Therefore, based on both morphological and molecular data, these specimens were identified as S. tubulosa . This report represents the first formal record of S. tubulosa in Chinese coastal waters, which extended its known geographical distribution.