elephants and the genus of devil's claws. The name of the genus Paramecia (an extinct red alga) is also the plural of the name of the genus Paramecium (which is in the SAR supergroup), which can also lead to confusion. A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). Use in higher classifications The type genus forms the base for higher taxonomic ranks, such as the family name ("Canids") based on Canis. However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is ("Carnivores"). Numbers of accepted genera The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of a total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and the International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: Animalia: 239,093 accepted genus names (± 55,350) Plantae: 28,724 (± 7,721) Fungi: 10,468 (± 182) Chromista: 11,114 (± 1,268) Protozoa: 3,109 (± 1,206) Bacteria: 3,433 (± 115) Archaea: 140 (± 0) Viruses: 851 (± 0) The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names; the values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda, with 151,697 ± 33,160 accepted genus names, of which