Strains YIM M 10366(T), YIM M 10378(T) and YIM M 10400(T) were isolated from marine sediments collected from the Xisha Islands in the South China Sea. All three isolates were able to grow optimally at pH 7.0, 28-37 �XC and 0-3% (w/v) NaCl. Comparison of 16S rRNA gene sequences showed that these strains are members of the genus Streptomyces, exhibiting moderately high 16S rRNA gene sequence similarities of 97.0-98.8% to members of the most closely related Streptomyces species. Morphological characteristics, physiological characteristics and compositions of whole-cell sugars and phospholipids are consistent with the diagnostic characteristics of the genus Streptomyces, but still allowed differentiation amongst the three strains and their neighbours. Based on 16S rRNA gene sequence analysis, DNA-DNA relatedness, phenotypic characteristics and chemotaxonomic data, strains YIM M 10366(T), YIM M 10378(T) and YIM M 10400(T) were identified as members of three novel species of the genus Streptomyces, for which the names Streptomyces glycovorans sp. nov. (type strain YIM M 10366(T) =DSM 42021(T) =CCTCC AA2010005(T)), Streptomyces xishensis sp. nov. (type strain YIM M 10378(T) = DSM 42022(T) =CCTCC AA 2010006(T)) and Streptomyces abyssalis sp. nov. (type strain YIM M 10400(T) =DSM 42024(T) = CCTCC AA 2010008(T)) are proposed.