PTILOCLADIA OKIENSIS SP-NOV (CERAMIACEAE, RHODOPHYTA) FROM THE SEA OFJAPAN

A new minute species of Ptilocladia is reported from the Sea of Japan. Thalli are up to 1 cm in height, robust, not calcified, brownish red, more or less alternately-distichously branched, have determinate bran ches and a pyramidal outline. Axes have no annulations and may or may not have rhizoidal cortication in the lower parts. Hexagonal crystals are absent from the axial cells. Gland cells are formed terminally or subterminally on whorl-branchlets and distributed throughout the thall us. Adventitious rhizoids are present but adventitious branches are ab sent. The third cells of carpogonial branches divide longitudinally to produce the carpogonium. Carposporophytes are borne on the indetermin ate branches as well as on the determinate branches. Usually five sper matangial mother cells are formed on terminal cells of whorl-branchlet s, each produces 2-4 spermatangia, and spermatangial sori extend throu ghout the thallus surface. Tetrasporangia are borne singly only on the basal cell of whorl-branchlets and distributed throughout the thallus .