Systematics is the process of characterizing and arranging bacterial diversity in an orderly manner, recognizing groups of similar organisms in a hierarchical scheme whose basic entity is the species. To allow the exchange of scientific knowledge, taxa have to be named. Taxa are not static entities since they are subject to evolution, the direction of which can be inferred by using a wide range of techniques targeting specific traits. However, it is not clear how this dynamism should be reflected in taxonomic nomenclature. In the present report, several considerations are presented that deal with the relationship between the evolution of taxa and their nomenclature; an example is given which concerns the nomenclature of the species Lactobacillus delbrueckii.