First report of the melobesioid alga (Corallinales, Rhodophyta) Mesophyllum incisum (Foslie) Adey in South Africa

Abstract

Mesophyllum incisum is reported and studied for the first time in South Africa. It has a th all us surface (SEM) with Leptophyturn-type epithallial cells. TetraJbisporangial conceptacles are mound-like and lack a peripheral rim but have a flattened pore plate. The rosette cells surrounding the tetrasporan gial po res are distinct from su rrounding roof cells (SEM, surface view) in be ing narrower, and sunken below the level of the surrounding pore plate. The cells of filaments bordering the tetrasporangial conceptacle pore canal differ from the othe r roof cells within the pore plate in being more elongate, narrower, and often more densely staining. Pore canal filaments also generally contain fewer cells than the surrounding filaments of the pore plate and th e pore can al is more-Dr-less parallel sided. Our material agrees closely with the species as reported in Australia.