Neosiphonia yendoi

Thallus fine filamentous, almost hairlike in ultimate branchlets, soft, bushy, to 5 cm high, often forming intertwined mats, reddish-brown, fading to yellowish-brown color. Branching irregularly alternate to dichotomous. Branches narrowly angled. Axes and branches of the first order 120-380 μm diam. at the lower part and 65-80 μm diam. in upper, of four pericentral cells. Corticated near the base. Cystocarps subspherical, large, (to 400 μm across). Attachment by rhizoids issuing from prostrate axes. Growing in the intertidal zone (rocky pools, crevices) and on upper subtidal rocks of exposed to strong wave and at semiprotected shores.

Japan (Hokkaido Island, Pacific coast of Honshu Island), Russia (the Sea of Japan, Peter the Great Bay, Sakhalin and Moneron Islands).