A bacterial strain was isolated from the water of Lake Martel in Mallorca (Spain). The isolate, designated MACL11(T), was halotolerant and strictly aerobic. The cells were non-motile, non-spore-forming, Gram-negative short rods. Comparative 16S rRNA gene sequence analysis revealed that MACL11(T) represents a separate line of descent within the order 'Rhizobiales' of the class 'Alphaproteobacteria'. Strain MACL11(T) was most closely related to the genera Rhizobium (93.3 % sequence similarity to Rhizobium rhizogenes), Aurantimonas (90.3 % sequence similarity to Aurantimonas coralicida) and Fulvimarina (90.3 % sequence similarity to Fulvimarina pelagi). Chemotaxonomically, strain MACL11(T) was characterized by the presence of Q-10 as the major respiratory lipoquinone. The major fatty acids detected were C(19 : 0) cycloomega8c, C(18 : 1)omega7c, C(16 : 0) and 11-methyl C(18 : 1)omega7c. The G+C content of the DNA was 57.4 mol%. Oxidase and catalase activities were present. Growth with many different carbohydrates as the sole carbon source was observed. The data from this polyphasic study suggest that this bacterium belongs to a novel genus of the order 'Rhizobiales' and is not associated with any of the known families of this order. It is proposed that isolate MACL11(T) should be classified in a novel genus and species, Martelella mediterranea gen. nov., sp. nov., with MACL11(T) (=LMG 22193(T)=CECT 5861(T)) as the type strain.