Two heterotrophic, aerobic, yellow-pigmented, Gram-negative, non-gliding bacteria, designated AKS293(T) and AKS432(T), isolated from a red alga, were analysed using a polyphasic taxonomic approach. 16S rRNA gene sequence analysis revealed that the novel strains were affiliated to the genus Lacinutrix, a member of the family Flavobacteriaceae, showing sequence similarities of 96.1-96.4 % with respect to the type strain of Lacinutrix copepodicola. The two novel isolates shared 99.5 % 16S rRNA gene sequence similarity and 55.0 % DNA-DNA relatedness. They grew optimally at 17.5 degrees C and pH 6.5. The main cellular fatty acids of strain AKS293(T) were iso-C(15 : 0), iso-C(15 : 0) 3-OH and iso-C(16 : 0) 3-OH, while those of strain AKS432(T) were anteiso-C(15 : 0), iso-C(15 : 0), iso-C(15 : 1) and iso-C(15 : 0) 3-OH. In both cases, the major isoprenoid quinone was MK-6. The DNA G+C contents were 34.7 and 37.0 mol% for strains AKS293(T) and AKS432(T), respectively. The phylogenetic evidence, phenotypic data and DNA-DNA hybridization results support the differentiation of strains AKS293(T) and AKS432(T) from each other and from their closest relative, L. copepodicola DJ3(T). Therefore, strains AKS293(T) and AKS432(T) represent two novel species, for which the names Lacinutrix algicola sp. nov. and Lacinutrix mariniflava sp. nov. are proposed, respectively. The type strain of L. algicola sp. nov. is AKS293(T) (=KCCM 42313(T)=JCM 13825(T)) and the type strain of L. mariniflava sp. nov. is AKS432(T) (=KCCM 42306(T)=JCM 13824(T)). An emended description of the genus Lacinutrix is also proposed.