Geissleria decussis is similar in shape to Placoneis clementis, but G. decussis is smaller and has capitate ends. Placoneis clementis also may have additional stigmata. Live cells of P. clementis have a different chloroplast number and structure. Navicula kotschyi is similar in shape, but possesses punctate striae, a feature not present in G. decussis.