Morphological and molecular studies on topotype material of Neoralfsia expansa (Phaeophyceae) reveal that Asian specimens assigned to this taxon are genetically distinct.

The genus Neoralfsia was newly described by P.-E. Lim and Kawai on the basis of rbcL sequence data from specimens from Japan and Malaysia identified as Neoralfsia expansa, and N. expansa [ Myrionema (?) expansum] from Mexico was designated as the type species. Our maximum likelihood and Bayesian analyses show that specimens of N. expansa from the type locality are grouped into a new, not previously described, clade in Neoralfsiaceae, distant from that of the putative specimens attributed to N. expansa from Japan and Malaysia. We show that genuine ' expansa' does not include Asian material. The distribution of the species is not as wide as has been previously recorded. [ABSTRACT FROM AUTHOR]