The genus is thought to be monotypic in North America. In Asia, L. superlacustris has broader valves (25-29 µm), lower stria (10-12 in 10 µm) and areola density (7.5-12 in 10 µm). Lacustriella acutocuneata has linear margins, a weakly expanded central area and acute apices. Lacustriella perapiculata has a weakly defined central area and a lower stria density (13-14 in 10 µm).