An actinobacterium strain BMG51109a was isolated from surface sterilized root nodules of Casuarina glauca collected in Tunisia. The 16S rRNA gene sequence of strain BMG51109a showed most similarity (96.53-96.55 %) to the type strains of Nocardia transvalensis, N. aobensis and N. elegans. Chemotaxonomic analysis supported the assignment of the strain to Nocardia genus. The major menaquinone was MK-8(H4c) while the polar lipid profile contained diphosphatidylglycerol, phosphatidylmonomethylethanolamine, glycophospholipid, phosphatidylinositol, one uncharacterized phospholipid and three glycolipids. Whole-cell sugar analysis revealed the presence of meso-diaminopimelic acid, arabinose and galactose as diagnostic sugars, complemented by glucose, mannose and ribose. The major cellular fatty acids were tuberculostearic, oleic, palmitoleic and stearic acids. Physiological and biochemical tests showed that strain BMG51109a could be clearly distinguished from its closest phylogenetic neighbours. On the basis of these results, strain BMG51109a(T) (= DSM 45978(T) = CECT 8469(T)) is proposed as the type strain of the novel species Nocardia casuarinae sp. nov.