A TAXONOMIC STUDY OF THE GENUS LAURENCIA (CERAMIALES, RHODOPHYTA) FROM VIETNAM .3. LAURENCIA CALLICLADA SP. NOV

Laurencia calliclada Masuda sp. nov. (Ceramiales, Rhodophyta), describ ed from Vietnam, is characterised by the following set of morphologica l features: 1) a basal system composed of a single disc from which a f ew, small, slender, softly fleshy, terete, upright axes develop; 2) th e production of four periaxial cells from each axial cell; 3) the pres ence of longitudinally oriented secondary pit-connection between conti guous superficial cortical cells; 4) surface cortical cells that proje ct in the upper portion of branches; 5) an absence of lenticular thick enings in the walls of medullary cells; and 6) a parallel arrangement of tetrasporangia. Furthermore, it produces a triterpenoid, calliclado l, as a major halogenated secondary metabolite that is unknown in any other algal species.