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A novel gamma-radiation-resistant and Gram-staining-positive actinobacterium designated BMG 8133(T) was isolated from a limestone collected in the Sahara desert of Tunisia. The strain produced dry, pale-pink colonies with an optimum growth at 35-40 degrees C and pH 6.5-8.0. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Geodermatophilus. The peptidoglycan contained meso-diaminopimelic acid as diagnostic diamino acid. The main polar lipids were phosphatidylcholine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine and one unspecified glycolipid. MK-9(H-4) was the dominant menaquinone. Galactose and glucose were detected as diagnostic sugars. The major cellular fatty acids were branched-chain saturated acids iso-C-16 : 0 and iSO-C-15 : 0. The DNA G + C content of the novel strain was 74.5 %. The 16S rRNA gene sequence showed highest sequence identity with Geodermatophilus ruber (98.3 %). Based on phenotypic results and 16S rRNA gene sequence analysis, strain BMG 8133T is proposed to represent a novel species, Geodermatophilus sabuli sp. nov. The type strain is BMG 8133(T) (=DSM 46844(T)=CECT 8820(T)).