Abstract

Leptochiton Gray, 1847 is the most well-known and species-rich genus within the family Leptochitonidae. Species of this genus inhabit a wide range of marine environments, from shallow coastal waters to cold, deepsea habitats. Due to the lack of distinctive morphological characters among congeneric species, the taxonomy of the genus has been complicated, making it difficult to distinguish between species based solely on external features. Recent studies using detailed morphological data obtained from scanning electron microscopy (SEM) have uncovered many cryptic species within the genus. L. rugatus (P. P. Carpenter, 1892) was once considered a single, widely distributed species across the northern Pacific. However, recent analysis incorporating morphological and molecular data have revealed that it is species complex that comprises several cryptic species. Over the last several decades, L. rugatus has been included in the National list of species in Korea with detailed descriptions, illustrations, SEM images, and distribution information. In this study, we reassessed the taxonomy of Korean L. rugatus species based on a comprehensive analysis of both morphological and molecular data (mtDNA cox1). The results from morphological and molecular phylogenetic analyses, referring to their geographic distribution information, revealed that L. rugatus species previously recorded in Korean waters should be taxonomically revised as L. subrugatus Sirenko & Sigwart, 2021. Based on this updated taxonomic information, we provide a detailed description of the microstructures of valves, girdle (perinotum and hyponotum), and radula for L. subrugatus from Korea.