All genera of the world: an overview and estimates based on the March 2020 release of the Interim Register of Marine and Nonmarine Genera (IRMNG)

We give estimated counts of known accepted genera of the world (297,930±65,840, of which approximately 21% are fossil), of a total 492,620 genus names presently held for “all life”, based on the March 2020 release of the Interim Register of Marine and Nonmarine Genera (IRMNG). A further c. 9,400 accepted genus names are anticipated to have been published over the period 2014–2019 which are not yet included in IRMNG; together with a lower confidence estimate that perhaps an additional 3,000 historic names are also missing from the present version of IRMNG, we therefore estimate that approximately 310,000 accepted generic names have been published to the end of 2019, with the holdings of IRMNG being around 96% complete. A breakdown of the data is presented by phylum and, in some cases, lower taxonomic group such as class or order; the actual lists of names on which the totals are based are available for download via the IRMNG web site and are also included as supplementary data to this paper. These data provide the most complete and consistent coverage of all kingdoms of life presently available in such a form and, despite their “interim” nature (not completely vetted by taxonomic experts, not all genera yet placed to family), serve to illustrate the scope of a project for a more detailed survey of “all genera of the world” as well as providing a comparison with existing lists (for example, to indicate names that may be missed from either side), and preliminary content that can be of value for the compilation of new lists. We note areas (chiefly very recently published names) where present IRMNG data may be incomplete and briefly address other issues encountered in the assembly of such data, including those associated with the construction of a unified and/or consensus classification within which genera and their containing families can be placed.