114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up the largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. Genus size The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles, which have about 1180 genera, the most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus, contains over 3,000 species. Which species are assigned to a genus is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance, the lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. See also List of the largest genera of flowering plants References External links Interim Register of Marine and Nonmarine Genera (IRMNG): includes an estimated 95% of published genus names (accepted and unaccepted) in all groups (semi-continuously updated) Nomenclator Zoologicus : index of genus and subgenus names (accepted and unaccepted) in zoological nomenclature from 1758 to 2004 Index to Organism Names: includes zoological taxon names at all ranks (including genera) as continuously indexed for the Zoological Record Index Nominum Genericorum (ING): a compilation of generic names (accepted and unaccepted) published for organisms covered by the ICN: International Code of Nomenclature for Algae, Fungi, and Plants (semi-continuously updated) LPSN – List of Prokaryotic names with Standing in Nomenclature: includes all currently accepted Bacteria and Archaea genus names (continuously updated) ICTV taxonomy releases: latest and historical lists of accepted virus names compiled