Sacs are uniformly round and up to 0.35 mm in diameter.
This species is commonly found in the bryozoan Fredericella sultana although DNA sequence data indicate that other bryozoans can also act as hosts (Anderson et al. 1999). Since these parasites are highly reduced and lack many distinguishing features, DNA sequence analysis is primarily used for species confirmation.
Other myxozoan parasites that produce sac-like stages in freshwater bryozoans may be confused with Tetracapsuloides bryosalmonae. However, Buddenbrockia allmani has only been recorded from the bryozoan Lophopus crystallinus while B. plumatellae is found in the bryozoan Cristatella mucedo.
Furthermore, the sac-like stages in these two species are generally irregular or oval in shape. Those produced by T. bryosalmonae are uniformly round. DNA sequences can also distinguish species (Tops et al. 2005).