Two strains, MKG-38(T) and FYK2402M69(T), were isolated from a marine sediment sample and a sea snail, respectively, both collected on the Pacific coast of Japan. Phylogeny of these new isolates based on 16S rRNA gene sequences indicated that they are members of the genus Lewinella. Morphological, physiological and biochemical properties of these two isolates, together with the type strains of the three previously described species of the genus Lewinella, were characterized. The new isolates were Gram-negative, aerobic, rod-shaped, chemo-organotrophic and able to degrade starch and CM-cellulose. A comparative polyphasic study showed that these two isolates represent two novel species of the genus Lewinella, for which the names Lewinella marina sp. nov. (type strain, MKG-38(T)=NBRC 102633(T)=NCIMB 14312(T)) and Lewinella lutea sp. nov. (type strain, FYK2402M69(T)=NBRC 102634(T)=NCIMB 14313(T)) are proposed. Emended descriptions of the genus Lewinella (Sly et al. 1998) and of Lewinella cohaerens, Lewinella nigricans and Lewinella persica are also proposed.