Phylogenetic relationships within the <i>Lottia kogamogai</i> species complex (Patellogastropoda: Lottiidae): a comparative study of morphology and habitat traits

ABSTRACT The Lottia kogamogai species complex consists of small lottiid limpets found in Japan and nearby coastal waters. It includes five species: L. luchuana, L. kogamogai, L. tenuisculpta, L. lindbergi and L. peitaihoensis. Molecular phylogenetic analysis using cytochrome c oxidase subunit I (COI), 16S ribosomal RNA and histone H3 genes, along with shell and radula morphology, suggests an additional undescribed species. Members are polyphyletic and divided into two lineages: North Pacific (NP) (L. tenuisculpta, L. lindbergi and Lottia sp.) and Indo-West Pacific + Australia (IWP + A) (L. luchuana, L. kogamogai and L. peitaihoensis). Haplotypes for L. tenuisculpta and L. lindbergi show different geographic patterns, suggesting expansion at different times. Lottia sp. is found only in Amami-Oshima, possibly due to the isolation of the Paleo Ryukyu Archipelago in the Pliocene. Morphological observations reveal that members show different shell surface sculpture, and shell dimensional ratios differ within L. tenuisculpta, L. lindbergi and Lottia sp. Lottia tenuisculpta was associated with various organic substrates, while L. lindbergi showed fewer variations and cases. The former is considered an epizoic species, while the epizoism of the latter remains controversial.