Chrysophyte stomatocyst production in laboratory culture and descriptions of seven cyst morphotypes

There is an extensive literature on chrysophyte stomatocysts from diverse habitats and their use as paleolimnetic indicators of past environmental conditions in lakes. The majority of these cysts are unidentified, and more laboratory studies are needed to link stomatocyst morphotypes to vegetative stages. A laboratory procedure that resulted in stomatocyst production in the chrysophyte alga Ochromonas pinguis (Chrysophyceae) was tested to determine if the protocol would also stimulate the production of stomatocysts in six other chrysophytes. Chrysolepidomonas dendrolepidota, Chrysosaccus cf. sphaericus, Dermatochrysis sp., Synura cf. americana, Synura cf. macropora and a second species of Ochromonas all produced stomatocysts within two to three weeks. Morphology of the stomatocyst was described using scanning electron microscopy (SEM). This was the first report of stomatocysts from Chrysosaccus and the first SEM description of O. pinguis cysts. These autecological studies provide a greater linkage between sediment stomatocysts and their biological origin, strengthening the interpretive value of these microfossils and broadening our understanding of chrysophyte biogeography.