Abstract

Five species of the red algal order Rhodymeniales are reported from Malaysia for the first time and their characteristic features are described: Chamaebotrys boergesenii (Weber-van Bosse) Huisman (Rhodymeniaceae), Coelarthrum sp. (Rhodymeniaceae), two species of Champia (Champiaceae), C. compressa Harvey and C. vieillardii Kützing, and Lomentaria monochlamydea (J. Agardh) Kylin (Lomentariaceae). The alga with vegetative features similar to the Chamaebotrys/Coelarthrum group is new to science and is characterised by the presence of a conspicuously developed, solid, cartilaginous stipe. This alga seems to be more closely related to Coelarthrum on the basis of its upright habit rather than Chamaebotrys, which has decumbent or prostrate thalli. The production of slender branches in Champia vieillardii is an additional critical feature that distinguishes it from a closely related species, C. compressa.