New records of Pseudoderma sinicarum and Lithophyllum nagaokaense (Lithophylloideae, Lithophyllaceae, Rhodophyta) from Korea

The subfamily Lithophylloideae includes non-geniculate coralline algal genera for which taxonomic uncertainty persists due to pronounced morphological plasticity and the limited availability of type-anchored molecular data. Here, we report Pseudoderma sinicarum and Lithophyllum nagaokaense as new records from Korea, identified based on plastid DNA markers (psbA and rbcL) and morpho-anatomical observations. Phylogenetic analyses showed that sequences from Korean specimens were identical and nearly identical to the corresponding holotype sequences, providing strong molecular support for their taxonomic identities. Morpho-anatomical comparisons showed that Korean specimens of L. nagaokaense were consistent with the original description from Japan, whereas those of P. sinicarum exhibited previously undocumented variation in hypothallial cell type (palisade vs. non-palisade), cell dimensions, and the persistence of bistratose construction compared with the original description from China. These findings demonstrate that characters traditionally used for generic delimitation in Lithophylloideae can exhibit intraspecific variation. By integrating type-anchored molecular evidence with morpho-anatomical assessment, this study expands the known geographic distributions of both species and contributes to understanding taxonomic complexity within Lithophylloideae.