The life history and ecology of the snow alga Chloromonas brevispina comb. nov. (Chlorophyta, Volvocales)

Snow algae previously designated as Cryocystis brevispina, Cryocystis japonica, Cryodactylon glaciale, Oocystis lacustris f. nivalis, Trochiscia cryophila, Trochiscia nivalis, and Trochiscia rubra were found to be developmental stages in the zygote of Chloromonas brevispina comb. nov. There is little evidence that Cryocystis and Cryodactylon are valid genera, as both appear to be zygotic phases of biflagellate volvocalean algae. In this life cycle, biflagellate vegetative cells, zoospores, gametes, syngamy and planozygotes are reported for the first time. The different morphological types of resting zygotes have been reported previously in the literature from most continents, but have been misinterpreted as several distinct taxa of snow algae. The environmental and physical factors pertaining to developmental stages in Chloromonas brevispina appear to be almost identical to those already reported for Chloromonas nivalis.