Planktic morphospecies of the cyanobacterial genus Anabaena = subg. Dolichospermum - 2. part: Straight types

Abstract

The planktic species of the traditional cyanobacterial genus Anabaena represent a special generic entity, different genetically as well as morphologically from the typical (benthic) part of the genus Anabaena, based on the type species Anabaena oscillarioides Bornet ex Bornet et Flahault. The group of planktic species should be classified in a special subg. Dolichospermum Thwaites ex Wittrock et Nordstedt 1889 with the type species Anabaena flos-aquae [Lyngbye] Brébisson ex Bornet et Flahault 1888, which should be transferred to the generic level. The subgenus Dolichospermum contains species of two morphological types, with coiled and straight trichomes. Populations of both these types are recognisable in nature without difficulties, but this very marked difference is variable and in disagreement with molecular results; it is particularly transient under culture conditions. It cannot be used therefore to the classification on higher than specific levels (with reservation). In spite of it, we have included the review of species with coiled trichomes in the first part of this list from practical reasons (Komárek & Zapomìlová 2007). In this second article are included the morphospecies occurring in nature mainly in straight trichomes. The detailed taxonomy of all these types should be solved in future, but our list should be a starting morphological review of this work. © Czech Phycological Society.