SCANNING ELECTRON MICROSCOPY OF CORALLINA AND HALIPTILON (CORALLINACEAE,RHODOPHYTA): SURFACE FEATURES AND THEIR TAXONOMIC IMPLICATIONS1

Scanning electron microscopy of intergenicula in members of the subfamily Corallinoideae reveals two distinctive surface morphologies: a Corallina-type (C-type) with round to irregular cell outlines and round trichocyte bases, and a Jania-type (J-type) with elongate, polygonal cell outlines and elongate trichocyte bases with excentric pores. The surface results from the calcified lateral walls of the epithallial cells projecting up from around collapsed protoplasts. Since J-type surfaces and trichocytes only occur in unequivocal members of the tribe Janieae—especially the genera Jania and Haliptilon, the presence of J-type surfaces in questionable members of Corallina reveals that they in fact belong to Haliptilon. Thus the two surface types clarify previously difficult taxonomic distinctions between Haliptilon and Corallina and allow identification to genus from purely vegetative material. Seventeen new combinations in Haliptilon are proposed. These results have considerable biogeographic implications with tropical species found to belong to Haliptilon, and Corallina sensu stricto being recognized primarily as a temperate and cold water genus.