Virescentia asiatica sp. nov. (Batrachospermales, Rhodophyta), a new freshwater red alga from East Asia

This study introduced a new species of freshwater red alga discovered in Taiwan, Virescentia asiatica sp. nov. Using genetic and morphological analyses, we determined its taxonomic status and phylogenetic relationship among other species of Virescentia (Sirodot) Necchi, D.C.Agostinho & M.L.Vis. While Virescentia taxonomy and species diversity have been extensively explored in Europe and the Americas, Asia remained less studied, with only one new species described in China. This study was the first record of Virescentia in Taiwan and confirmed it as a new species, Virescentia asiatica sp. nov. The investigation was based on comparing morphological characteristics and genetic markers rbcL and COI-5P in collections from around the world. Molecular evidence showed what we describe as V. asiatica sp. nov. forming a well-supported clade with four previously unidentified Virescentia sequences from Japan, and conspecific with at least three of these. We considered it likely that V. asiatica sp. nov. inhabited a wider geographic range in East Asia, including other regions besides Taiwan and Japan. Morphologically, Virescentia asiatica sp. nov. was distinct only in habit, differing from other Virescentia species in having an apparently diminutive thallus and curved branching. This study enhanced our understanding of the classification and phylogenetic relationships within Virescentia, contributing to the knowledge of freshwater red algae biodiversity in East Asia.