ABSTRACT
The ranking decision needed for the phylogenetic species concept (PSC) that was described in the previous chapter (for deciding which clades should be called species) was clearly arbitrary. This chapter is based on the recognition that the “species problem” is a special case of the “taxon problem” that has already been addressed for higher taxonomic levels by advocates of phylogenetic nomenclature and rankless classification, as codified in the recently published PhyloCode. The species rank should be eliminated following the same arguments (Mishler 1999, 2010). We need to transition to rankless classification “all the way down,” including the rank currently known as species, and the PhyloCode needs to be modified to allow this (Cellinese, Baum & Mishler 2012). The smallest clades that are named in a particular group can be called SNaRCs (smallest named and registered clades) but there is no implication that these are necessarily comparable in any way (Mishler & Wilkins 2018).
