The family Clostridiaceae (scientific name) defined by the taxonomic outline of Bergey's Manual of Systematic Bacteriology contains as its core the genus Clostridium (sensu stricto), as well as Acetivibrio, Acidaminobacter, Alkaliphilus, Anaerobacter, Caloramator, Caloranaerobacter, Coprobacillus, Dorea, Natronincola, Oxobacter, Sarcina, Sporobacter, Thermobrachium, Thermohalobacter, and Tindallia.

This misclassification is the result of well-known problems of the current taxonomic structure of the traditional genus Clostridium.

The phylogenetic analysis of Collins (1994) was the first large-scale comparison of 16S rRNA gene sequences of species of the genus Clostridium and related taxa.

The comparative study of Collins (1994) and subsequent studies can be used to conclude that more than half of the species currently assigned to this genus are in fact not closely related to the type species, C. butyricum, and from a phylogenetic standpoint should not be included in a newly defined genus Clostridium.

[3] However, on the basis of 16S rRNA gene sequence analyses, only 73 of these fall within the radiation of the type species of the genus Clostridium.