The Taxonomy of the Genus <em>Entamoeba</em> (Archamoebea: Endamoebidae): A Historical and Nomenclatural Review

Throughout history, species within the genus Entamoeba have been described using a set of criteria that have not always been applied consistently, resulting in a taxonomy that is often confusing and controversial. Several factors have influenced the application of these criteria, including the limited number of morphological characters useful for taxonomic studies, overlapping host ranges among many species, the occurrence of mixed infections in some hosts, and a cosmopolitan distribution largely associated with human and animal movements. The incorporation of biochemical and genetic data as diagnostic and differential criteria, following the development of these techniques in the second half of the twentieth century, has enabled the recognition of cryptic species as well as the proposal of new taxa; however, significant taxonomic issues remain unresolved. This review summarises the historical development and main controversies in the taxonomy of the genus Entamoeba, from its origins in the late nineteenth century, when morphology and host association were the only available criteria, to the present day, in which molecular approaches provide a more realistic view of species diversity and interspecific relationships. Based on this analysis, general principles are proposed as a pragmatic synthesis to guide future taxonomic work on Entamoeba.