ALEXANDRIUM-SATOANUM SP-NOV (DINOPHYCEAE) FROM MATOYA BAY, CENTRAL JAPAN

The gonyaulacoid dinoflagellate Alexandrium satoanum Yuki et Fukuyo sp. nov, is described from Matoya Bay, Pacific coast of central Japan. The species is distinctive in its conical epitheca with almost straight sides and dorsal concavity of the hypotheca. The plate formula is Po, Pc, 4' 6'', 6c, 10s, 5''', and 2'''', including two accessory plates inside the sulcus. The apical pore plate is triangular and possesses an anterior attachment pore at the right margin. The first apical plate does not make contact with the apical pore plate and lacks a ventral pore. A posterior attachment pore lies at the center of the posterior sulcal plate. In Matoya Bay, vegetative cells occur as solitary cells or sometimes in pairs during late spring and early summer in low concentrations. In connection with this study, the following new combination is proposed: Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo comb. nov.