[The application of a numerical method to the taxonomy of the genus Leishmania Ross, 1903,--The recognition of 146 original lines in the Old World. Use of allozymic characters. Epidemiological and phyletic significance (author's transl)].

Using enzyme characters determined by starch gel electrophoresis, the authors have applied the method of Numerical Taxonomy to the genus Leishmania Ross, 1903. Eight isoenzymes (PGI, ME, PGM, GOT, G-6-PDH, 6-PGDH, MDH and IDH) of 146 Old World strains are examined. 35 electromorphs, corresponding to equivalent number of isoenzymes, are identified by this method, and then grouped into 14 zymodemes. These zymodemes were used as Operational Taxonomy Units (OTU) and pairs were compared, using Jaccard's index of similarity. A matrix of association was constructed using these indices and it forms the basis for the taxonomic scheme elaborated. The final relationships are exhibited in the agglomerative dendrogram, constructed using complete linkage. The separation into phylons is confirmed by correspondence analysis. It is concluded that the original lines fall into five groups corresponding to the complexes Leishmania donovani, Leishmania tropica, Leishmania major, Leishmania aethiopica and cf. Leishmania tarentolae. The phylons as recognised by Numerical Taxonomy, can be equated with the taxa of traditional systematics. The phyletic significance of the individualized phylons is then provided by a genetic approach. Thus, it is possible to compute the genetic distances of Nei with allozyme frequency values of 0,0.5 and 1. The new dendrogram is similar to the previous one: Leishmania major constitutes an homogeneous taxon, long isolated from the others. Leishmania donovani and Leishmania tropica have retained a nonnegligible amount of genetic similarity, attesting both a common origin and a more recent evolutionary divergence.