A novel Gram-stain-positive, aerobic actinomycete, designated strain SMC 195, was isolated from soil collected from a mangrove forest in Thailand. The strain produced extensively branched substrate and aerial mycelia. The substrate mycelium was fragmented into rod-shaped elements, and spore chains consisting of smooth and rod-shaped spores were formed on the aerial mycelium. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that SMC 195 represented a member of the genus Pseudonocardia, and the most closely phylogenetically related species were Pseudonocardia yuanmonensisJCM 18055 (99.2 % 16S rRNA gene sequence similarity), Pseudonocardia halophobicaNRRL B-16514 (98.9 %) and Pseudonocardia kujensisNRRL B-24890 (98.7 %). However, the DNA-DNA relatedness values between SMC 195and the closest phylogenetically related species were significantly below 70 %. The G+C content of the genomic DNA was 74±0.8 mol%. The cell wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars consisted of arabinose, galactose, glucose, rhamnose and ribose. The menaquinone was MK-8(H4) only. The major cellular fatty acid was the branched fatty acid iso-C16 : 0 (33.6 %). The polar lipids detected were phosphatidylethanolamine, phosphatidylmethylethanolamine, hydroxyphosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol and unidentified glycolipids. On the basis of the results from phenotypic, chemotaxonomic and genotypic studies, it is concluded that SMC 195 represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia mangrovi sp. nov. is proposed. The type strain is SMC 195 (=TBRC 7778=NBRC 113150).