A new species Erythrotrichia bohanensis sp. nov. (Erythropeltales, Rhodophyta) from the coast of China

<i>Erythrotrichia</i> (Erythropeltales, Rhodophyta) is a group of widely distributed marine epiphytic algae. With the advancement of molecular biology in recent years, the classification of this genus has undergone significant changes, revealing several morphologically indistinguishable cryptic species. In this study, we collected species of <i>Erythrotrichia</i> from the Bohai Sea coast of China, proposed a new species-<i>Erythrotrichiabohanensis</i> <b>sp. nov.</b> based on laboratory culture, morphological observation and molecular phylogenetic analysis. Phylogenetic analyses, including <i>rbc</i>L and SSU gene sequence analyses, demonstrated that <i>Erythrotrichiabohanensis</i> <b>sp. nov.</b> clusters into an independent branch with high Maximum Likelihood (ML) bootstrap values and Bayesian Inference phylogenies (BI) posterior probabilities. The new species is characterized by an unbranched, filamentous thallus and exhibits both asexual and sexual reproduction. The main morphological differences of the new species are primarily reflected in its sexual reproduction process. The carpogonium and spermatium are formed by the expansion and division of vegetative cells, and fertilization occurs outside the thallus. The establishment of this new species underscores the cryptic species diversity within this taxon and implies that additional morphological, molecular, and genetic information is essential for more precise species identification.