sphingomonas stygia sphingomonas stygia sphingomonas stygia is a species of bacteria. it is an aromatic compound-degrading bacteria, it is gram-negative, non-spore-forming, non-motile and rod-shaped. it is found in deep-terrestrial-subsurface sediments. sphingomonas stygia scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: sphingomonadales family: sphingomonadaceae genus: sphingomonas binomial name sphingomonas stygiabalkwill et al. 1997 synonyms novosphingobium stygium (takeuchi et al. 2001)