Description of a New Species of the Intertidal Limpet <i>Patelloida</i> (Patellogastropoda: Lottiidae) from Wakayama and Kochi, Japan.

This study presents a comprehensive examination of a recently identified intertidal limpet species, <i>Patelloida parva</i> n. sp., utilizing a multidisciplinary approach that combines molecular analyses and detailed morphological investigations. Molecular analysis, involving mitochondrial (16S rRNA) and recently reported single nucleotide polymorphism markers, has been instrumental in distinguishing <i>Patelloida parva</i> n. sp. from its congeners. In addition to genetic divergence, this study provides a description of both morphology and species distribution, revealing key features that set <i>Patelloida parva</i> n. sp. apart from closely related <i>Patelloida</i> species found in Japan. <i>Patelloida parva</i> n. sp. is mainly distributed in the upper intertidal of the Pacific coasts of Wakayama and Kochi Prefectures, Japan, but morphological analysis suggests that there are also populations on the Ryukyu Islands. Furthermore, this study hypothesizes the tropical origin of <i>Patelloida parva</i> n. sp., attributing its distribution pattern to the influence of the Kuroshio Current. Genetic analyses indicate a closer sequence divergence (5%) to the tropical <i>P. saccharinoides</i> compared to the <i>P. lanx</i> (11%) co-occurring in intertidal rocky shores. This study not only contributes to the understanding of the species' ecology but also underscores the importance of considering both genetic and morphological aspects in the taxonomy of limpets within <i>Patelloida</i>.