A new genus, Volatus and four new species of Batrachospermum sensu stricto (Batrachospermales, Rhodophyta)

Collections of Batrachospermales from 13 stream sites in North America (Canada and United States), Europe (Spain) and Asia (China) were examined. Phylogenetic analyses of sequences data from the plastid-encoded ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) and the mitochondrial-encoded cytochrome oxidase 1 gene barcode region (COI-5P), along with morphological studies, suggested that these collections represent new taxa. Three species in a proposed new genus Volatus are described: V. carrionii sp. nov., V. personatus sp. nov. and V. ulterior sp. nov. Four new species of Batrachospermum sensu stricto are also described: B. dapsile sp. nov., B. naiadis sp. nov., B. pozoazulense sp. nov. and B. shanxiense sp. nov. Taxa proposed based on the molecular analyses were in many cases difficult to distinguish with unique morphological characters. The new genus Volatus shares the distinctive characteristic of twisted or curled carpogonium-bearing branches with Kumanoa and Tuomeya but was not sister to either of these genera, suggesting that this character may have arisen at least three times in the order. The three species of Volatus were distinguished from each other based on molecular data and, in part, geographic distribution. The proposed Batrachospermum species B. naiadis sp. nov., B. pozoazulense sp. nov. and B. shanxiense sp. nov. overlap in both vegetative and reproductive characters with each other and B. gelatinosum. Batrachospermum dapsile had a distinguishing character of monosporangia in clusters arising from the periaxial or proximal cells and terminal or subterminal on primary fascicles.