NEW OBSERVATIONS ON THE HETEROTROPHIC PROTIST GENUS THAUMATOMASTIX (THAUMATOMASTIGACEAE, PROTISTA INCERTAE SEDIS), WITH PARTICULAR EMPHASISON MATERIAL FROM THE BALTIC SEA

Thaumatomastix (Thaumatomastigaceae, Protista incertae sedis) is a gen us of swimming or gliding heterotrophic protists sporadically reported from both marine and freshwater habitats. The cell carries two flagel la, one of which is covered by scales, while the other is naked. Both flagellar scales and body scales are produced in vesicles located in c lose proximity to the outer membranes of the tubulocristate mitochondr ia. Scales are silicified. In addition to spineless, oval or triangula r body scales, in most cases formed by the partial fusion of two almos t equally sized plates, some species also possess species-specific spi ne scales. The genus at present comprises seven species. Six of these are found in samples from the brackish Baltic Sea. However, only T. sa lina (syn. Chrysosphaerella salina) has been frequently observed in el ectron microscopical whole mounts. Three new species are described: Th aumatomastix spinosa sp. nov., Thaumatonastix dybsoeana sp. nov. and T haumatomastix formosa sp. nov.