Panta Rei: taxonomic changes and stability of terrestrial Cetartiodactyla over time

The number of recognised taxa tends to change continually over time in many groups of animals. It can be hypothesised, however, that non-elusive, relatively large taxa of great appeal to humans would show a high taxonomic stability over time. We test this hypothesis using the former order Artiodactyla (now Cetartiodactyla) as a case study. To do so, we compare the main checklists of known mammalian species published over time, analysing the temporal changes and the underlying reasons for the observed patterns. Our study revealed (i) the occurrence of four peak phases of new species descriptions in Cetartiodactyla between 1758 and 2020; and (ii) a prominent peak of new descriptions for the family Bovidae (and, to a lesser extent, Cervidae) from 2005 to 2020, with the number of species increased by more than 95%. New taxa came almost exclusively from splitting (= revisions of the existing taxa) and very rarely from newly discovered species. So, the new taxonomic arrangements were essentially due to revisions of the existing taxa. Overall, our study only partially confirms the above-mentioned hypothesis.