Cladistic analyses produce either pure cladograms, phylograms with distinctive branch lengths, or time-calibrated cladograms (chronograms, timetrees). In any case, only clades with robust statistical support should be given names. In zoological taxonomy, the rules for applying clade names are traditionally defined by the International Code of Zoological Nomenclature (ICZN). The rules only pertain to clades of lower hierarchical ranks (genera, tribes, and family groups), and strictly follow the principle of priority. ICZN stipulates that family-group and tribal names have fixed suffixes (-oidea, -idae, -inae, -ini, and -ina). Above superfamily level, clade names can be freely chosen. 

Orders of birds and fishes are traditionally indicated by the Latin suffix -(i)formes, while order names of mammals and invertebrates have no consistent pattern.

In 2019, a number of ICZN critics objecting to the use of clade names that are burdened with ranks released the International Code of Phylogenetic Nomenclature. Proponents of this “PhyloCode” want to abolish imposed arbitrary ranks (aside from the genus level that has no fixed suffix and forms part of the binomial species name). They justifiably argue that ranks provide relative hierarchy-level information only within a given clade, but lack equivalence among clades. 

In my view, zoologists are not well-advised to tolerate the existence of two competing codes of nomenclature. A first step towards bridging differences might be the application of „temporal banding“ that allows ranks to be linked to evolutionary ages (see Note: “Temporal banding”). 



Cantino PD, and de Queiroz K  (2020), International code of phylogenetic nomenclature (PhyloCode), version 6, CRC Press, Boca Raton, FL, (pdf) (buy hardcopy)


De Queiroz K, Cantino PD, and de Gautier JA  (2020), Phylonyms: a companion to the PhyloCode, 1st edition, CRC Press, Boca Raton, FL. (abstract) 

Dubois A (2006a), New proposals for naming lower-ranked taxa within the frame of the International Code of Zoological Nomenclature, C. R. Biol. 329, 823-840. (pdf)


Dubois A (2006b), Proposed rules for the incorporation of nomina of higher-ranked zoological taxa in the International Code of Zoological Nomenclature, 2. The proposed Rules and their rationale, Zoosystema 28, 165-258. (pdf)


Hillis DM (2007), Constraints in naming parts of the Tree of Life, Mol. Phylogenet. Evol. 42, 331-338. (abstract) 

Kuntner M, and Agnarsson I (2006), Are the linnean and phylogenetic nomenclatural systems combinable? Recommendations for biological nomenclature, Syst. Biol. 55, 774-784. (pdf)