Trichome structure of fourAphanizomenontaxa (Cyanophyceae) from Czechoslovakia, with notes on the taxonomy and delimitation of the genus

The dimension and variation range of terminal and intercalary cells, heterocysts, and akinetes of fourAphanizomenontaxa occurring in Czechoslovakia were studied. Statistical and graphical procedures were used for evaluation. With regard toA. flos-aquae,the results support the distinction of two varieties (var.flos-aquaeand var.klebahnii). In the samples determined asA. graciletwo clearly distinguishable morphological types could be found; one of them is recognized as a new species:A. flexuosum.Its diacritical features are established and problems of the intrageneric taxonomy ofAphanizomenonand its demarcation from the genusAnabaenaare discussed.