ALGAE OF THE FAMILY GRACILARIACEAE (GRACILARIALES, RHODOPHYTA) FROM THE RUSSIAN PACIFIC COASTS

Abstract

Algae of the family Gracilariaceae represent economically important seaweed resources of the Russian Pacific though they are few in number. Only two species of Gracilaria were for certain recorded from this area: G. textorii with flattened frond and the alga with terete frond known for a long time as G. verrucosa. Lately it was treated in Russian literature as G. gracilis, however it raised our doubts. Up to now taxonomy of these algae was understudied, so our purpose was to clarify it. Our study revealed that "G. gracilis" represented two different species. One was described as a new species Gracilaria austramaritima Przhemenetskaya in Selivanova et al., 2008. The other one had morphological similarity with G. vermiculophylla from the south-eastern Asia (Vietnam, China, Japan). Molecular data (cox1) confirmed that algae from the Russian Pacific coasts identified as G. gracilis in fact represented G. vermiculophylla. Comparison of G. austramaritima and G. vermiculophylla revealed their difference in gross morphology and life cycles. Gracilaria austramaritima has much in common with G. rhodocaudata from Japan but differs from the latter and other morphologically close species from the North Pacific by huge size and the absence of nutritive filaments in the gonimoblast. Molecular data showed close affinity of G. austramaritima with Gracilaria (=Gracilariopsis) chorda. Thus there are at least three species of Gracilaria in the Russian Pacific: G. textorii, G. vermiculophylla and G. austramaritima. Additional studies are necessary to clarify phylogenetic relationships of G. austramaritima and Gracilariopsis chorda.