Some aspects on the morphology and ecology of Rhodomonas minuta var. nannoplanctica and R. lens (Cryptophyceae) in two Greek lakes

Significant morphological and ecological differences between Rhodomonas minuta var. nannoplanctica and R. lens were observed during the study of phytoplankton in two Greek lakes. The shape and size characteristics support the validity of these species, so the fusion of closely related species of Rhodomonas proposed by Javornicky is not accepted in this study. Apart from the morphological differences between Rhodomonas minuta var. nannoplanctica and R. lens contrasting ecological requirements were noticed. A broader distribution of Rhodomonas minuta var. nannoplanctica in relation to temperature and pH and a preference for lower nutrient concentrations than R. lens were found. The two taxa may coexist by shifting their niches at different times in Lake Volvi and by vertical niche separation in Lake Vegoritis.