Abstract

Polysiphonia morrowii (Rhodomelaceae, Rhodophyta) is abundant in intertidal zones of the northwestern Pacific Ocean in spring, and has been introduced to the Mediterranean Sea. We collected specimens of this species from intertidal rocks in February in Punta Arenas, in southernmost Chile. Thalli were densely tufted, slender, and elongate, with four pericentral cells, no cortication and short tetrasporangial ultimate branchlets. The plastid protein-coding rbcL was analyzed from specimens collected in Chile and Korea, as well as from putative relatives. The rbcL sequences of the Chilean specimens were almost identical to those from Korea, and were clearly separated from other related taxa from Chile and other areas. These results suggest that P. morrowii has been introduced recently from the northwestern Pacific Ocean to Chile.