Staurosira leptostauron var. dubia is similar in shape to Staurosira construens var. venter and Staurosirella pinnata. Staurosirella pinnata differs from S. leptostauron var. dubia by its smaller valves, oval valve outline and narrower striae. In addition, the costae of S. pinnata are usually narrower than the striae and spines are well-developed. The striae of Staurosira construens var. venter differ from those of S. leptostauron var. dubia by their narrower width. Furthermore, Staurosira construens var. venter has well-developed spines. Finally, S. leptostauron var. dubia is more heavily silicified than S. pinnata and S. construens var. venter.