The pit connections of some lower red algae: Ultrastructure and phylogenetic significance

Abstract

The ultrastructure of pit connections in twelve rhodophycean algae in the Bangiales and the Nemaliales has been investigated. All pit connections in the organisms investigated have the same basic substructure. A membrane-bounded plug is situated in the pore of the septum and on each side of the plug is a membrane-bounded plug cap. Usually there is condensed material associated with membranes outside the plug caps. The plasmalemma is continuous from cell to cell. The phylogenetic significance of the substructure of the pit connections within the red algae, and in relation to septal structures in the Basidiomycetes and the Ascomycetes, is discussed.