Rhizobium grahamii sp. nov., from nodules of Dalea leporina, Leucaena leucocephala and Clitoria ternatea, and Rhizobium mesoamericanum sp. nov., from nodules of Phaseolus vulgaris, siratro, cowpea and Mimosa pudica.

Two novel related Rhizobium species, Rhizobium grahamii sp. nov. and Rhizobium mesoamericanum sp. nov., were identified by a polyphasic approach using DNA-DNA hybridization, whole-genome sequencing and phylogenetic and phenotypic characterization including nodulation of Leucaena leucocephala and Phaseolus vulgaris (bean). As similar bacteria were found in the Los Tuxtlas rainforest in Mexico and in Central America, we suggest the existence of a Mesoamerican microbiological corridor. The type strain of Rhizobium grahamii sp. nov. is CCGE 502(T) (= ATCC BAA-2124(T) = CFN 242(T) = Dal4(T) = HAMBI 3152(T)) and that of Rhizobium mesoamericanum sp. nov. is CCGE 501(T) (= ATCC BAA-2123(T) = HAMBI 3151(T) = CIP 110148(T) = 1847(T)).