Numerical Taxonomy of the Genus Nocardia

SUMMARY By a numerical classification, strains received as Nocardia asteroides were divided into two clusters; these two groups were named as N. asteroides (Eppinger) Blanchard and N. farcinica Trevisan, respectively, recognizing the name of N. farcinica for the group which included strain atcc 3318, received as N. asteroides. The genus Nocardia was divided into 7 groups; (1) N. asteroides (in a new sense); (2) N. brasiliensis; (3) N. caviae; (4) N. farcinica; (5) a group provisionally named N. rubra; (6) N. pelletieri; (7) N. madurae. The species provisionally named N. rubra was made up of strains which, when received from other workers, bore 8 species names: N. rubra, N. erythropolis, N. globerula, N. convoluta, N. minima, N. lutea, N. rubroper-tincta and N. polychromogenes. Relationships between seven species of Nocardia are shown as a dendrogram, and descriptions of characteristics (here called Hypothetical Mean Organism) of the species are presented. A method called numerical identification is presented by which identification can be made, without subjective judgement, by comparison of the characters of a test strain with the Hypothetical Mean Organism after permissible limits of S-values for the Hypothetical Mean Organism have been established.