CYTOMORPHOLOGICAL CHARACTERS SUPPORTING THE TAXONOMIC VALIDITY OF CYANOTHECE (CYANOPROKARYOTA)

The fine structure of the type species of the genus Cyanothece KOMAREK 1976, C. aeruginosa, is described and compared with the main cytologi cal characteristics of morphologically related members of the genera C yanobium, Cyanobacterium and Synechococcus. Several morphological feat ures, such as cell walls with thick outer layers containing a special type of vesicles, position of thylakoids, ''keritomy'' (net-like appea rance of protoplast caused by arrangement of thylakoids, net-like nucl eoids and/or by tendency to form intrathylakoidal spaces) and a specia l structure of mucilaginous envelopes were found to be characteristic of this genus, supporting its separate position among coccal cyanoprok aryotes (cyanobacteria, cyanophytes). The taxonomic significance of ul trastructural features in all mentioned genera is discussed.