Monophyletic origin of freshwater sponges in ancient lakes based on partial structures of COXI gene

The phylogenetic relationships between freshwater sponges (families Lubomirskiidae, Spongillidae and Potamolepidae) are still poorly understood. Partial sequences of the cytochrome oxidase subunit I (COXI) gene were obtained from seven freshwater sponge species and one marine sponge. Phylogenetic analyses showed that all the freshwater sponge species formed one common clade and they appeared to be closely related. These results indicate that freshwater sponges are of monophyletic origin. Potamolepidae and Spongillidae are situated at the base of the tree and are assumed to be phylogenetically older than Lubomirskiidae.