Morphological and Phylogenetic Analysis of a New Jellyfish of Phyllorhiza (Scyphozoa, Mastigiidae) from the East China Sea

A new species of jellyfish, <i>Phyllorhiza yurena</i> Chen, Hu & Xing sp. nov., is described from the East China Sea based on an integrative approach combining morphological and molecular data. Specimens were collected from coastal waters and cultured in the laboratory to observe their complete life cycle, including polyps, ephyrae, and medusae. Distinct morphological features such as the blue lappet stems in ephyrae, white warts on the exumbrella, and multiple short club-shaped appendages on the mouth arms distinguish the new species from its congeners. Phylogenetic analyses based on mitochondrial (<i>COI</i>, <i>16S</i>) and nuclear (<i>18S</i>, <i>28S</i>) gene markers confirmed its taxonomic distinctiveness, with <i>COI</i> and <i>16S</i> markers providing the most resolution. The study highlights the importance of combining life history observations with molecular tools for accurate jellyfish taxonomy and provides a revised identification key for the genus <i>Phyllorhiza</i>. This discovery contributes to the understanding of jellyfish biodiversity in the East China Sea and offers a baseline for future ecological and biogeographic studies.