Revisiting the taxonomy of Korean Ischnochiton species (Polyplacophora, Ischnochitonidae) based on a combined analysis of morphological and molecular data

In this study, we compared the microstructural characteristics of tegmentum sculpture, girdle scales and radula amongst four Korean <i>Ischnochiton</i> species using high-resolution microscopic images and a scanning electron microscope (SEM). Along with mtDNA <i>cox1</i> sequence comparison, a comprehensive analysis of their morphology revealed that <i>I.hayamii</i> Owada, 2018 was identified for the first time in Korean waters. This species is morphologically distinguished by its small body size of adults, smooth lateral areas on valves and small perinotum scales sculptured with weak longitudinal ribs. Phylogenetic analysis of the mtDNA <i>cox1</i> sequence provides distinct resolution at the species level, but interrelationships amongst <i>Ischnochiton</i> species remain unresolved. Results from the morphological and molecular analyses presented in this study offer valuable taxonomic information for accurate species identification amongst closely-related <i>Ischnochiton</i> species.