Morphology, reproduction, genetics, and mating behavior of small, tropical marine Brachionus strains (rotifera)

Small, tropical marine Brachionus (SS strains) are distinguished by their lorica size and shape, Their relation to other marine Brachionus species, however, remains unknown. We examined morphometry, reproductive mode, allozyme patterns and mating behavior among marine Brachionus species in an attempt to classify SS strains. Based on morphological features, reproductive mode, and allozyme patterns, SS strains were most similar to those of B. rotundiformis Tschugunoff. Observations on mating behavior between different groups indicated that there is reproductive isolation between B. plicatilis O.F. Muller and B. rotundiformis and between B. plicatilis and SS strains. In contrast, copulation was observed between B. rotundiformis and SS strains. Thus, there is no evidence that SS strains are a new marine Brachionus species, and most likely should be included in B. rotundiformis.