Two extremely halophilic archaea, strains RO1-28(T) and RO1-22, were isolated from a marine solar saltern in Jiangsu, China. Both strains required at least 0.05 M Mg(2+) and 1.7 M NaCl for growth. They were able to grow over a pH range of 6.0-8.5 and a temperature range of 25-55 degrees C, with optimal pH of 7.0 and optimal temperature of 37-40 degrees C. Based on 16S rRNA gene sequence analysis, strains RO1-28(T) and RO1-22 were closely related to Haladaptatus paucihalophilus, the single species of the genus Haladaptatus, with similarities of 94.0-95.2 %. The major polar lipids of the two strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and three glycolipids chromatographically identical to the glycolipids of Haladaptatus paucihalophilus JCM 13897(T). Both strains RO1-28(T) and RO1-22 had a DNA G+C content of 54.0 mol% (HPLC). The DNA-DNA hybridization value between the two strains was more than 70 % (92 %) and both strains showed low levels of DNA-DNA relatedness (32 % and 33 %) with Haladaptatus paucihalophilus JCM 13897(T). It was concluded that strains RO1-28(T) and RO1-22 represent a novel species of the genus Haladaptatus, for which the name Haladaptatus litoreus sp. nov. is proposed. The type strain is RO1-28(T) (=CGMCC 1.7737(T) =JCM 15771(T)).