Phylogenetic analysis of partial rpoB gene sequences of type and clinical strains belonging to different 16S rRNA gene-fingerprinting ribogroups within 11 species of enterobacteria of the genera Proteus, Morganella and Providencia was performed and allowed the definition of rpoB clades, supported by high bootstrap values and confirmed by ?2.5 % nucleotide divergence. None of the resulting clades included strains belonging to different species and the majority of the species were confirmed as discrete and homogeneous. However, more than one distinct rpoB clade could be defined among strains belonging to the species Proteus vulgaris (two clades), Providencia alcalifaciens (two clades) and Providencia rettgeri (three clades), suggesting that some strains represent novel species according to the genotypes outlined by rpoB gene sequence analysis. Percentage differences between the rpoB gene sequence of the type strain of Proteus myxofaciens and other members of the same genus (17.3-18.9 %) were similar to those calculated amongst strains of the genus Providencia (16.4-18.7 %), suggesting a genetic distance at the genus-level between Proteus myxofaciens and the rest of the Proteus-Providencia group. Proteus myxofaciens therefore represents a member of a new genus, for which the name Cosenzaea gen. nov., is proposed.

Multiple isolates of the genus Providencia were obtained from the haemolymph of wild-caught Drosophila melanogaster fruit flies. Sixteen isolates were distinguished from the six previously described species based on 16S rRNA gene sequences. These isolates belonged to two distinct groups, which we propose each comprise previously undescribed species. Two isolates, designated A(T) and B(T), were characterized by DNA sequences of the fusA, lepA, leuS, gyrB and ileS housekeeping genes, whole-genome DNA-DNA hybridizations with their nearest relatives and utilization of substrates for metabolism. The closest phylogenetic relatives of strain A(T) are strain B(T) (86.9 % identity for the housekeeping genes) and Providencia stuartii DSM 4539(T) (86.0 % identity). The closest phylogenetic relatives of strain B(T) are strain A(T) (86.9 % identity) and P. stuartii DSM 4539(T) (86.6 % identity). The type strains of described species in this genus shared between 84.1 and 90.1 % identity for these sequences. DNA-DNA hybridization between the strain pairs A(T)-B(T), A(T)-P. stuartii DSM 4539(T) and B(T)-P. stuartii DSM 4539(T) all resulted in less than 25 % relatedness. In addition, patterns of utilization of amygdalin, arbutin, aesculin, salicin, d-sorbitol, trehalose, inositol, d-adonitol and d-galactose distinguish strains A(T) and B(T) from other members of this genus. Strains A(T) and B(T) therefore represent novel species, for which the names Providencia sneebia sp. nov. (type strain A(T) =DSM 19967(T) =ATCC BAA-1589(T)) and Providencia burhodogranariea sp. nov. (type strain B(T) =DSM 19968(T) =ATCC BAA-1590(T)) are proposed.