We have made a polyphasic taxonomic study of strain 5CR T , isolated from Fuente de Piedra, Má laga, southern Spain. The strain is a moderately halophilic, Gram-negative rod, oxidase-positive and motile by a single polar flagellum. It does not produce acids from sugars and shows respiratory metabolism, using oxygen, nitrate and nitrite as terminal electron acceptors. It requires NaCl and grows best with 5-7.5 % w/v at temperatures of between 32 and 45 6C within a pH range of 6-8. Its 16S rRNA gene sequence indicates that strain 5CR T belongs to the genus Halomonas in the class Gammaproteobacteria. Its closest relatives are Halomonas alimentaria, H. nitroreducens, H. shengliensis and H. ventosae, with the type strains of which our strain showed 16S rRNA gene sequence similarity values of 96.7-97.8 %. DNA-DNA hybridization studies between strain 5CR T and H. ventosae CECT 5797 T , the phylogenetically nearest type strain, showed 40 % relatedness. Its G+C content is 65.7 mol%. Its major fatty acids are C 18 : 1 v7c (31.36 %), C 16 : 0 (25.55 %), C 16 : 1 v7c/iso-C 15 : 0 2-OH (23.23 %), C 19 : 0 cyclo v8c (8.14 %), C 12 : 0 3-OH (5.76 %) and C 10 : 0 (2.22 %) and the predominant respiratory lipoquinone is ubiquinone with nine isoprene units (Q-9). The proposed name for the novel species is Halomonas fontilapidosi sp. nov., strain 5CR T (5CECT 7341 T 5LMG 24455 T ) being the type strain.The family Halomonadaceae of the class Gammaproteobacteria comprises seven genera, Carnimonas, Chromohalobacter, Cobetia, Halomonas, Halotalea, Modicisalibacter and Zymobacter (Euzéby, 2008). Chromohalobacter, Cobetia, Halomonas and Modicisalibacter are composed of halophilic bacteria whereas Carnimonas, Halotalea and Zymobacter contain non-halophilic bacteria (Ben Ali Gam et al., 2007;Garrity et al., 2005;Ntougias et al., 2007). The genus Halomonas currently contains more than 50 species (Euzéby, 2008). Its members are Gram-negative, rodshaped, non-sporulated, aerobic chemo-organotrophs, with predominantly respiratory metabolism, using oxygen, nitrate or nitrite as electron acceptors. Few Halomonas species produce acids from sugars (see Mata et al., 2002;Dobson & Franzmann, 1996;Franzmann et al., 1988;Vreeland, 2005;Arahal et al., 2007). They are widely distributed throughout hypersaline environments. Some of them are recognized for their potential use in biotechnology (Margesin & Schinner, 2001;Ventosa & Nieto, 1995), producing exopolysaccharides (Arias et al., 2003;Mata et al., 2006;Martínez-Checa et al., 2002), denitrifying (Peyton et al., 2001; Yoshie et al., 2006) or degrading aromatic compounds (García et al., 2004).We have already described some novel halophilic taxa isolated from Fuente de Piedra (Málaga, Spain): Idiomarina fontislapidosi (Martínez-Cánovas et al., 2004c), Halomonas anticariensis (Martínez-Cánovas et al., 2004b) and strain 15CR of Halomonas cerina (González-Domenech et al., 2008a). Furthering our research into bacteria in this area, we subjected strain 5CR T to a polyphasic taxonomic investigation and as ...