An extremely halophilic archaeon belonging to the order Halobacteriales was isolated from Fuente de Piedra salt lake, Spain. This strain, designated FP1(T), was a pleomorphic coccoid, neutrophilic and required at least 15 % (w/v) NaCl for growth. Strain FP1(T) grew at 37-60 degrees C, with optimal growth at 50 degrees C. Mg(2+) was not required, but growth was observed with up to 10 % (w/v) MgSO(4). Polar lipid analysis revealed the presence of mannose-6-sulfate(1-2)-glucose glycerol diether as a major glycolipid. Both C(20)C(20) and C(20)C(25) core lipids were present. The genomic DNA G+C content was 62.0 mol%. Phylogenetic analysis based on comparison of 16S rRNA gene sequences demonstrated that the isolate was most closely related to species of the genus Haloterrigena. DNA-DNA reassociation values between strain FP1(T) and the most closely related species of the genus Haloterrigena (Haloterrigena thermotolerans, Haloterrigena saccharevitans and Haloterrigena limicola) were lower than 29 %. It is therefore considered that strain FP1(T) represents a novel species of the genus Haloterrigena, for which the name Haloterrigena hispanica sp. nov. is proposed. The type strain is FP1(T) (=DSM 18328(T)=ATCC BAA-1310(T)).