Confirming a synonym of the sea slug Philine orientalis spreading in Jiaozhou Bay, China

Abstract

A philinid population outbreak occurred in Jiaozhou Bay in 2022, resulting in large yield losses on cultured Ruditapes philippinarum (A. Adams & Reeve, 1850) and significant economic losses for farmers. We applied a combination of morphological and molecular methods to identify the spreading population of philinids in Jiaozhou Bay. Evident morphological differences were observed in shells and gizzard plates of the spreading philinids, but molecular results showed that the philinids belong to one single species: Philine orientalis (A. Adams, 1854). Additionally, we found that Philine kinglipini Tchang, 1934 was a junior synonym of P. orientalis. Although P. orientalis was an invasive species in northeast Pacific regions, the population spreading in Jiaozhou Bay was native. Our results might provide useful information for the control and management of this spreading species.