Abstract

Hypnea cornuta (Kützing) J. Agardh var. stellulifera J. Agardh (Hypneaceae, Gigartinales) is distinguished from the type variety by the short, thick, rigid axes that produce thick adventitious branchlets as well as the tetrasporangial sori and spermatangial sori that extend to the parental axis and branches. Var. stellulifera is raised to the rank of species as Hypnea stellulifera (J. Agardh) Yamagishi et Masuda on the basis of these morphological differences and comparative chloroplast-encoded rbcL sequences. Reproductive structures of Heterosiphonia crispella (C. Agardh) Wynne (Dasyaceae, Ceramiales), which is referable to var. laxa (Borgesen) Wynne, are described. Two species of Laurencia (Rhodomelaceae, Ceramiales) are reported from Malaysia for the first time: L. pygmaea Weber-van Bosse and L. majuscula (Harvey) Lucas. Critical features of L. pygmaea include four pericentral cells per segment, the presence of a single (rarely two) corps en cerise per superficial cortical cell, and the production of a single tetrasporangium-bearing pericentral cell on each fertile segment.