Morphology and halogenated secondary metabolites of Laurencia snackeyi (Weber–van Bosse) stat. nov. (Ceramiales, Rhodophyta)

Abstract

The marine red alga known as Laurencia obtusa var. snackeyi (Weber–van Bosse) Yamada (Rhodomelaceae, Ceramiales) is characterized as follows: (1) production of 4 periaxial cells from each axial cell; (2) a few, percurrent, terete, thick main axes arising from a single discoid holdfast without stolon-like branches; (3) alternate-spiral branching; (4) presence of longitudinally oriented secondary pit-connections between contiguous superficial cortical cells; (5) absence of a palisade-like layer; (6) absence of projecting superficial cortical cells; (7) absence of lenticular thickenings in the walls of medullary cells; (8) parallel arrangement of tetrasporangia; and (9) presence of one corps en cerise per superficial cortical cell and trichoblast cell. It differs from L. obtusa (Hudson) Lamouroux in the absence of stolon-like branches with secondary attachment discs and the presence of thicker axes. The following binomial is proposed: Laurencia snackeyi (Weber–van Bosse) Masuda, stat. nov. Halogenated secondary metabolites of this species were investigated for samples from Vietnam and Malaysia. The major metabolites of the Vietnamese sample are palisadin A and aplysistatin, both sesquiterpenoids, whereas the Malaysian samples contain these compounds along with another monocyclofarnesol-derived sesquiterpenoid, 5-acetoxypalisadin B. L. snackeyi is also characterized by this set of secondary metabolites.