Sheathia shaoguanensis sp. nov. (Batrachospermales, Rhodophyta), a new freshwater red algal species from South China

The freshwater red algal order Batrachospermales has a triphasic life history, of which the morphological characteristics of “Chantransia” stages are very similar to those of the genus Audouinella . In this study, two gametophyte stage specimens (CQM21 and CQW23) and four “Chantransia” stage specimens (CQ003, CQM22, CQW24, and GD247) were collected from Chongqing Municipality and Guangdong Province in China. Based on morphological data, all four “Chantransia” isolates were similar to A. pygmaea , whereas the morphological characteristics of CQM21 and CQW23 were in good agreement with the circumscription description of Sheathia dispersa . The rbc L and COI-5P analyses suggested that all six specimens belong to the genus Sheathia and supported the proposal of a new species, S. shaoguanensis sp. nov . Nevertheless, the five specimens from Chongqing (including the two gametophyte stage and three “Chantransia” stage specimens) were all assigned to S. dispersa . This represents the first report of the genus Sheathia in the Yangtze River.