[8] It is defined on a node-based approach as the least inclusive clade containing the species Dictyostelium discoideum (a dictyostelid), Physarum polycephalum (a myxogastrid) and Ceratiomyxa fruticulosa (a protosporangiid).

[3] The following cladogram is based on a 2022 analysis:[9] Tubulinea Discosea Cutosea Archamoebae Dictyostelia Myxogastria Protosporangiida Variosea The name Eumycetozoa was first used by German mycologist Friedrich Wilhelm Zopf in 1884, although no formal taxonomic rank was given.

[1] In 1975, mycologist Lindsay Shepherd Olive reintroduced the name Eumycetozoa as a class containing the three groups of fruiting amoebae traditionally included in this taxon: Myxogastria, Dictyostelia and Protostelia.

The protosteloid type of fruiting body formation, initially considered the ancestral feature shared between all Eumycetozoa, has evolved independently at least in eight lineages within Amoebozoa (e.g. soliformoviids, cavosteliids, schizoplasmodiids, protosporangiids).

[12] To preserve this widely used name, biologist Seungho Kang and his coauthors redefined Eumycetozoa in 2017 to include only one group of protosteloid amoebae, the Protosporangiida (also known as Ceratiomyxomycetes), which are a monophyletic taxon.

[3][7] This usage corresponds to the 1975 hypothesis from Olive that postulates a clade of exclusively fruiting protists that includes myxogastrids, dictyostelids, and some protosteloid amoebae (in this case, the protosporangiids).