Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980) pro synon. Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980) pro synon. Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) Universal Root Woese et al. 1990 Bacteria (None 2015) Woese et al. 1990 Proteobacteria (sic) Garrity et al. 2021 Pseudomonadota corrig. Garrity et al. 2021 Alphaproteobacteriota (sic) Garrity et al. 2021 Gammaproteobacteria Garrity et al. 2005 emend. Williams and Kelly 2013 Enterobacterales (Garrity and Holt 2001) Adeolu et al. 2016 Morganellaceae Adeolu et al. 2016 Providencia Ewing 1962 (Approved Lists 1980) Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980) pro synon. Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) Providencia Ewing 1962 (Approved Lists 1980) Providencia rettgeri (Hadley et al. 1918) Brenner et al. 1978 (Approved Lists 1980) pro synon. Proteus rettgeri (Hadley et al. 1918) Rustigian and Stuart 1943 (Approved Lists 1980) Providencia heimbachae Müller et al. 1986 Providencia vermicola Somvanshi et al. 2006 Providencia thailandensis Khunthongpan et al. 2014 Providencia stuartii (Buttiaux et al. 1954) Ewing 1962 (Approved Lists 1980) Providencia rustigianii Hickman-Brenner et al. 1983 Providencia sneebia Juneja and Lazzaro 2009 Providencia burhodogranariea Juneja and Lazzaro 2009 Providencia friedericiana Müller 1983 Providencia huaxiensis Hu et al. 2019 Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980) pro synon. Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) Liolios K. Chen I.M. Mavromatis K. Tavernarakis N. Hugenholtz P. Markowitz V.M. Kyrpides N.C. The Genomes On Line Database (GOLD) in 2009: status of genomic and metagenomic projects and their associated metadata 2010 38 D346 354 Nucleic Acids Research Nucleic Acids Res. 0305-1048 1362-4962 10.1093/nar/gkp848 19914934 Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980) pro synon. Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) Dauga C. Evolution of the gyrB gene and the molecular phylogeny of Enterobacteriaceae: a model molecule for molecular systematic studies 2002 52 2 531 547 International Journal of Systematic and Evolutionary Microbiology Int J Syst Evol Microbiol 1466-5026 1466-5034 10.1099/ijs.0.01926-0 11931166 Skerman V.B.D. McGowan V. Sneath P.H.A. Approved Lists of Bacterial Names 1980 30 1 225 420 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-30-1-225 Liolios K. Chen I.M. Mavromatis K. Tavernarakis N. Hugenholtz P. Markowitz V.M. Kyrpides N.C. The Genomes On Line Database (GOLD) in 2009: status of genomic and metagenomic projects and their associated metadata 2010 38 D346 354 Nucleic Acids Research Nucleic Acids Res. 0305-1048 1362-4962 10.1093/nar/gkp848 19914934 Ewing W.H. The tribe Proteae: its nomenclature and taxonomy. 1962 12 93 102 International Bulletin of Bacteriological Nomenclature and Taxonomy Int Bull Bacteriol Nomencl Taxon 0096-266X 10.1099/0096266X-12-3-93 Proteus inconstans (Ornstein 1920) Shaw and Clarke 1955 (Approved Lists 1980) Ewing W.H. The tribe Proteae: its nomenclature and taxonomy. 1962 12 93 102 International Bulletin of Bacteriological Nomenclature and Taxonomy Int Bull Bacteriol Nomencl Taxon 0096-266X 10.1099/0096266X-12-3-93 Skerman V.B.D. McGowan V. Sneath P.H.A. Approved Lists of Bacterial Names 1980 30 1 225 420 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-30-1-225 Lautrop H. Buchanan R.E. Gibbons N.E. Genus X. Proteus Mauser 1885, 12 1974 8 327 330 Bergey's Manual of Determinative Bacteriology The Williams and Wilkins Co. Baltimore 0683011170 de Salles Gomes L. Sobre uma nova especie do genero Eberthella Buchanan de fezes pathologicas de crianca, Eberthella acalifaciens (n. sp.). 1944 14 182 195 Revista do Instituto Adolfo Lutz 0073-9855 Users are advised that there is a nomenclatural issue with the genus Providencia. According to the rule of priority, Proteus inconstans (an earlier homotypic synonym) has priority over Providencia alcalifaciens. However, if the rule of priority is followed, Providencia and its species become illegitimate and lose standing in nomenclature. A request for an opinion to conserve the name Providencia alcalifaciens over the earlier name Proteus inconstans is needed to resolve this issue.