Calliandra grandiflora has been used as a medicinal plant for thousands of years in Mexico. Rhizobial strains were obtained from root nodules of C. grandiflora collected from different geographical regions in Chiapas and characterized by BOX-PCR, amplified rDNA restriction analysis (ARDRA) and 16S rRNA gene sequence analysis. Most isolates corresponded to members of the genus Rhizobium and those not related to species with validly published names were further characterized by recA, atpD, rpoB and nifH gene phylogenies, phenotypic and DNA-DNA hybridization analyses. Three novel related species of the genus Rhizobium within the 'Rhizobium tropici group' share the same symbiovar that may be named sv. calliandrae. The names proposed for the three novel species are Rhizobium calliandrae sp. nov. (type strain, CCGE524T=ATCC BAA-2435T=CIP 110456T=LBP2-1T), Rhizobium mayense sp. nov. (type strain, CCGE526T=ATCC BAA-2446T=CIP 110454T=NSJP1-1T) and Rhizobium jaguaris sp. nov. (type strain, CCGE525T=ATCC BAA-2445T=CIP 110453T=SJP1-2T). © 2013 IUMS.