The fine structure of Mastigocladopsis repens Hernandez-Marine, Fernan
dez et Merino, a filamentous Stigonematalean cyanophyte, is described.
The scheme of vegetative cells is similar to others members of the gr
oup. The slope of the not transversal division septum in the main fila
ment produces either true T-branching or Y-branching. The mature heter
ocysts present a well-developed homogeneous extra wall and laminated l
ayer. Comparison with some features of other genus are presented.