Four strains, designated JPY-345 T , JPY-347, JPY-366 and JPY-581, were isolated from nitrogen-fixing nodules on the roots of two species of Mimosa, Mimosa cordistipula and Mimosa misera, that are native to North East Brazil, and their taxonomic positions were investigated by using a polyphasic approach. All four strains grew at 15–43 6C (optimum 35 6C), at pH 4–7 (optimum pH 5) and with 0–2 % (w/v) NaCl (optimum 0 % NaCl). On the basis of 16S rRNA gene sequence analysis, strain JPY-345 T showed 97.3 % sequence similarity to the closest related species Burkholderia soli GP25-8 T , 97.3 % sequence similarity to Burkholderia caryophylli ATCC25418 T and 97.1 % sequence similarity to Burkholderia kururiensis KP23 T. The predominant fatty acids of the strains were C 18 : 1 v7c (36.1 %), C 16 : 0 (19.8 %) and summed feature 3, comprising C 16 : 1 v7c and/or C 16 : 1 v6c (11.5 %). The major isoprenoid quinone was Q-8 and the DNA G+C content of the strains was 64.2–65.7 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and several uncharacterized aminophospholipids and phospholipids. DNA–DNA hybridizations between the novel strain and recognized species of the genus Burkholderia yielded relatedness values of ,51.8 %. On the basis of 16S rRNA and recA gene sequence similarities and chemotaxonomic and phenotypic data, the four strains represent a novel species in the genus Burkholderia, for which the name Burkholderia symbiotica sp. nov. is proposed. The type strain is JPY-345T ( = LMG 26032T  = BCRC 80258T  = KCTC 23309T).