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A black-pigmented, aerobic actinobacterium, tolerant to ionizing radiation, designated BMG 825 T, was isolated from desert limestone dust in Tunisia. The strain grew within the temperature range 10-40 degrees C , at pH 5.5-11.0 and in the presence of 2% NaCl. The DNA G+C content was 75.7 mol%, and its cell-wall peptidoglycan contained meso-diaminopimelic acid. Sugars of whole-cell hydrolysates were galactose, glucose, and trace amounts of ribose and mannose. The predominant menaquinone was MK-9(H-4), and the major fatty acids were iso-C-16:0 and C-16:1 omega 7c. The polar lipid profile comprised phosphatidylcholine, phosphatidylinositol, diphosphatidylglycerol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine and an unspecified glycolipid. 16S rRNA gene sequence analysis revealed that the strain fell into the genus Geodermatophilus, showing the highest similarity with Geodermatophilus poikilotrophus DSM 44209(T) (99.1 %). DNA-DNA hybridization results, phylogenetic distinctiveness and phenotypic properties supported the classification of this strain as a representative of a novel species of the genus Geodermatophilus, for which the name Geodermatophilus pulveris sp. nov. is proposed. The type strain is BMG 825(T) (=CECT 9003(T) =DSM 46839(T)).