In systematics one must distinguish between crown clades and total clades. While total clades include all extant and all extinct members of a given clade, crown clades comprise just the last common ancestor of the extant representatives of that clade and all its descendants. In other words, crown clades do not encompass representatives of the stem group. 

The demand for a clear distinction between crown clades and total clades poses the question how to separate them linguistically. Creating entirely new names for total clades, as both ICZN and ICPN suggest or tolerate (Louchard et al., 2013; de Queiroz, 2007; Cantino & de Queiroz, 2020; de Queiroz et al., 2020), might lead to a plethora of new names. It must be noted, however, that the PhyloCode (chapters 10.3 to 10.7) is miles ahead of the ICZN-Code in providing explicit statements on the use of the prefix “-Pan”. 

Therefore, I favour the proposal of Lauterbach (1989) to simply add the hyphenated prefix "pan-" to the crown-clade name to create an informal taxonomic name for the total clade, like pan-Aves. In my view, this rule should be applied rigorously, without exceptions. 

In their paper on Strisores, Chen & Field (2020) suggest the total-clade names Pan-Trochilidae and Pan-Apodiformes for the respective crown clades, but for the total clade of the crown clade Strisores they propose the name Caprimulgimorphae, instead of Pan-Strisores. Although conforming to the rules of the PhyloCode, the name Caprimulgimorphae should not be adopted by the ornithological community.  



Cantino PD, and de Queiroz K (2020), International code of phylogenetic nomenclature (PhyloCode), version 6. www.phylonames. org. (link)


de Queiroz K (2007), Toward an integrated system of clade names. Syst. Biol. 56, 956-974. (pdf)


de Queiroz K, Cantino PD, and Gauthier JA (2020), Phylonyms - A companion to the PhyloCode. CRC Press, Boca Raton, FL, USA(link)


Haug C, and Haug JT (2015), The ambiguous use of the prefix 'Pan' in arthropod systematics, RRJZS 3, 19-24. (pdf)


Joyce WG, Anquetin J, Cadena EA, Claude J, Danilov IG, Evers SW, Ferreira GS, Gentry AD, Georgalis GL, Lyson TR, Perez-Garcia A, Rabi M, Sterli J, Vitek NS, and Parham JF (2021), A nomenclature for fossil and living turtles using phylogenetically defined clade namesSwiss J. Palaeontol. 140: 5.  (pdf)


Lauterbach KE (1989), Das Pan-Monophylum: Ein Hilfsmittel für die Praxis der phylogenetischen Systematik, Zool. Anz. 223, 139-156. (inaccessible at the moment)


Louchart A, Viriot L, and Dubois A (2013), The use of the prefix Pan- and other problems in zoological family-level nomenclature, Zootaxa 3750, 197-200. (pdf)


Meier R, and Richter S (1992), Suggestions for a more precise usage of proper names. Ambiguities related to the stem lineage concept, J. Zool. Syst. Evol. Res. 30, 81-88. (abstract)