Thorea Bory de Saint-Vincent(Rhodophyta)is a genus of freshwater red algae whose species level taxonomic status was long disputed attributable to poor sample representativeness and seemingly random distribution.In recent years,molecular evidence led to the establishment of the new order Thoreales.However,the phylogeny of the recognized species and their dispersal pattern remained unclear.We analyzed most of the known Thorea samples,including two samples found in Shanxi,China,based on sequences of two conserved genes,the chloroplast rbcL and the nuclear 18S rDNA.We reconstructed phylogenetic trees by Bayesian analysis(BA),maximum likelihood(ML),and maximum parsimony(MP).Trees for both genes consistently recovered a distinct clade including all Thorea samples.The Thorea clade was closely related to Nemalionopsis Skuja than to species in Batrachospermales,supporting the recognition of Thoreales.Two Thorea hispida(Thore)Desvaux samples from China formed a single clade related to conspecific samples from Japan.T.okadae Yamada from Japan was also sister to T.hispida,suggesting it could be a synonym of T.hispida rather than of T.violacea Bory de Saint-Vincent.Additionally,geographic information combined with the rbcL tree indicated that Thorea originated in the Northern Hemisphere,most probably in Asia,despite the disjunction between Asia and North America.