Species delimitation in the filiform, oppositely branched members of the genus Desmarestia Lamour. (Phaeophyceae, Desmarestiales) in the northern hemisphere

Abstract

Analyses of character variation in populations of terete, oppositely branched members of the genus Desmarestia in the northern hemisphere indicated a lack of non-overlapping criteria by which D. viridis and D. media may be differentiated. Accordingly, these two species (and the varieties of D. media) are considered to be conspecific and referred to the older name, D. viridis. An extended knowledge of the morphology of D. viridis has shown that type specimens of the north Pacific species D. farcta, D. pacifica, and D. filamentosa may be included in the range of variation of D. viridis. Therefore, these three species are reduced to synonymy of D. viridis. D. kurilensis is considered to be sufficiently distinct to warrant specific status. The known range of the species has been extended from the Kurile Islands to British Columbia and central California.