New record of Gracilaria firma Chang et Xia (Rhodophyta) from Okinawa, Japan

SUMMARY Gracilaria firma Chang et Xia is newly recorded for Japan, where it grows at Okinawa Island, on the Pacific coast of the Ryukyu Archipelago. This species is characterized by (i) cylindrical axes with a discoid holdfast; (ii) branches and branchlets constricted at their bases; (iii) acute to blunt apices; (iv) colour greenish‐brown to yellowish‐brown; (v) scarce traversing filament between the dense gonimoblast and the pericarp; and (vi) deep, pot‐shaped Verrucosa‐type spermatangial conceptacles. The Japanese specimens agree well with previously known South‐East Asian specimens as well as the original description of G. firma from south China.