Strain H2R21(T), a novel actinobacterium, isolated from a forest soil sample collected from Heybeliada, Istanbul, Turkey, and a polyphasic approach was used for characterisation of the strain. Chemotaxonomic and morphological characterisation of strain H2R21(T) indicated that it belongs to the genus Nonomuraea. 16S rRNA gene sequence similarity showed that the strain is closely related to Nonomuraea purpurea 1SM4-01(T) (99.1%) and Nonomuraea solani CGMCC 4.7037(T) (98.4%). DNA-DNA relatedness values were found to be lower than 70% between the isolate and its phylogenetic neighbours N. purpurea 1SM4-01(T), N. solani CGMCC 4.7037(T) and Nonomuraea rhizophila YIM 67092(T). The whole cell hydrolysates of strain H2R21(T) were found to contain meso-diaminopimelic acid as the diagnostic diamino acid and glucose, madurose, mannose and ribose as the cell sugars. The polar lipids were identified as phosphatidylglycerol, diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, dihydroxy-phosphatidylethanolamine, phosphatidylinositol, glycophosphatidylinositol, two glycophospholipids and two unidentified lipids. The predominant menaquinones were identified as MK-9(H-4) and MK-9(H-6). The major fatty acids were found to be iso-C-16:0, iso-C-16:0 2OH and C-17:0 10-methyl. On the basis of DNA-DNA relatedness data and some phenotypic characteristics, it is evident that strain H2R21(T) can be distinguished from the closely related species in the genus Nonomuraea. Thus, it is concluded that strain H2R21(T) represents a novel species of the genus Nonomuraea, for which the name Nonomuraea insulae sp. nov. is proposed. The type strain is H2R21(T) (=DSM 102915(T) =CGMCC 4.7338(T) =KCTC 39769(T)).