Bryozoans comprise a phylum of sessile, clonal animals, inhabiting marine and freshwater environments. Only around 90 species have been described from freshwater habitats, most belonging to the class Phylactolaemata. Phylactolaemates can propagate asexually by forming encapsulated dormant bodies called statoblasts, which provide characters highly useful in phylactolaemate taxonomy and identification. To date, 23 species of phylactolaemate species in ten genera have been reported from Japan, however their taxonomical review has been never reported. Furthermore, current taxonomy of phylactolaemates is heavily depending on the observation of statoblast microsculpture by using scanning electron microscopy, which causes difficulty of simple identification. In this paper, major characters of colony and statoblast for all species of Japanese freshwater bryozoans including both 23 phylactolaemates and three ctenostomes are summarized. A key to species based on colony and statoblast gross morphology is also provided for help in identification of freshwater bryozoans in various fields such as faunal survey and education.
