Bacterial strains isolated from diseased erythrina (Erythrina sp.) trees in Martinique (French West Indies) were studied using phenotypic tests, 16S rDNA sequence analysis and DNA-DNA hybridization. Numerical analysis of phenotypic characteristics showed that these strains formed an homogeneous phenon among plant-pathogenic Enterobacteriaceae, and gave useful and updated information for the identification of these bacteria. Results of DNA-DNA hybridization indicated that strains from erythrina belonged to a discrete genomospecies (89-100% hybridization) and had low levels of DNA relatedness (2-33% hybridization) with reference strains of phytopathogenic Erwinia, Brenneria, Pectobacterium, Pantoea and Enterobacter species. 16S rDNA sequence analysis using three different methods revealed that the position of strain CFBP 5236T isolated from erythrina was variable in the different trees, so that strains from erythrina could not be assigned to any recognized genus. It is proposed that these strains are included in a new genus, Samsonia. The name Samsonia erythrinae is proposed for the new species. The G+C content of the DNA of the type strain, CFBP 5236T (= ICMP 13937T), is 57.0 mol%.