Hidden diversity of <i>Pyropia dentata</i> complex (Bangiales, Rhodophyta) in Japan, with description of a new species <i>Pyropia neodentata</i> from the Pacific coast of Japan

SUMMARY To clarify the genetic diversity of the Pyropia dentata complex in Japan, we conducted molecular analyses and morphological observations using samples collected from Amakusa region (the type locality), on the East China Sea coast, Hirado, on the Sea of Japan coast, and Enoshima, on the Pacific coast of Japan. Molecular phylogenetic analyses of the rbc L gene clearly indicated that the samples from Enoshima ( Pyropia cf. dentata in a previous study) were a different species from P. dentata collected from Amakusa and Hirado. The samples from Amakusa and Hirado were also genetically different from each other based on the phylogenetic tree. However, it was inferred that the samples collected from these two localities reflected intraspecific variation in P. dentata . Although the morphological features of the samples from the three localities were similar, the samples from Enoshima differed from the samples from Amakusa and Hirado in the blade thickness and the division formula of zygotosporangia. Based on the molecular phylogenetic analyses and morphological observations using the samples from Enoshima, we describe a new species, Pyropia neodentata . Furthermore, this study demonstrated that the new species is distributed on the Pacific coast of Japan, whereas P. dentata is widely distributed from the East China Sea coast to the Sea of Japan coast, including Korea and China.