Microglena redcarensis sp. nov. (Volvocales, Chlorophyceae), a brackish water chlamydomonad with contractile vacuoles

In 1960, Butcher isolated a strain of unicellular green alga, ‘Chlamydomonas subehrenbergii’ SAG 18.89, from a brackish water locality in England, facing the North Sea. Although C. subehrenbergii Butcher was previously described by the same author in 1959, the strain SAG 18.89 is in fact morphologically different, possessing shorter flagella, a different-shaped papilla, and different-sized vegetative cells. Light and fluorescence microscopy, molecular phylogenetic analyses, and ITS2 comparisons revealed that this strain represents an undescribed species of the genus Microglena (Volvocales, Chlorophyceae), described here as M. redcarensis sp. nov. The presence of contractile vacuoles, which are osmoregulatory organelles, suggests potential inhabitation in freshwater. Contractile vacuole activity and growth of M. redcarensis were therefore examined in media of different salinity.