Sellaphora saugerresii has a lower stria density. Sellaphora atomoides is similar to S. nigri with overlapping size range, but valves of S. atomoides are generally more narrow with a higher stria density and have a distinctly rectangular or bow-tie shaped central area. Sellaphora atomoides has been verified from aerial habitats and more 'pristine' conditions, while S. nigri is believed to be far more widespread and tolerant of polluted environments. Sellaphora disjuncta is larger and has subcapitate ends.