Abstract:Parastrombidinopsis minima n. sp. is investigated, using live observations, protargol preparations, and molecular data. In living cells, the ranges of cell length are 85-95 microm, cell width 60-70 microm, and oral diameter 40-50 microm. In protargol-impregnated specimens, cell length ranges between 43 and 71 microm, cell width between 23 and 42 microm, and oral diameter between 13 and 24 microm. The numbers of external oral polykinetids are 12-16 and of somatic kineties are 11-13. There are always two ovoid macronuclei (9-16 x 4-9 microm). Based on the analysis of morphologic data, the new species can be placed in the family Strombidinopsidae, but based on the small subunit rRNA gene sequence data, the Parastrombidinopsis species are more closely associated with strobilidiids and tintinnids.