A new species of Mallomonas, M. kalinae, is described from a small peaty pool Ostrov in the Bohemian Switzerland National Park (northern Bohemia). The species is located in the section Papillosae and its morphological characteristics are closest to M. rasilis, M. calceolus, M. binocularis and M. paxillata. However, it can be distinguished from these species by differences in scale and bristle morphology. Itwas previously reported from different parts of theworld, but its taxonomic status remained unrecognized due to the lack of a detailed investigation of cultured material. The taxonomy and distribution of the species are discussed and compared with information in the literature.