Abstract
Two mycoplasmas, Mycoplasma hyopneumoniae Mare and Switzer 1965 and M. suipneumoniae Goodwin et al. 1965, have been named and described as etiological agents in enzootic pneumonia of pigs. Authentic cultures of strain 11, the type strain of M. hyopneumoniae, are no longer extant. Strain J, the type strain of M. suipneumoniae, is here proposed as the neotype strain of M. hyopneumoniae. Since the names M. hyopneumoniae and M. suipneumoniae are now based on the same type, they are objective synonyms. The name M. hyopneumoniae, being the earlier of the two, has priority and is therefore the correct name of the species. The name M. suipneumoniae is thus illegitimate as a later, objective synonym. Another swine isolate, M. flocculare, although sharing a number of biological features with strains of M. hyopneumoniae, is nevertheless serologically distinct not only from the latter but also from all of the other currently recognized species of Mycoplasma. It is thus confirmed here as a unique species. Biological and serological characterizations of the type and proposed neotype strains are given.