Observations of two new species of Navicula: N. exiloides and N. delicatilineolata

Abstract

Two Navicula species are newly described from several Japanese rivers and a pond. Navicula exiloides nov. sp. resembles Navicula exilis, but differs in the size range, apical shape, angle of striation and areola density Although Navicula delicatilineolata nov. sp. bears similarities to Navicula heimansioides, they are distinguishable by the shape of both the valve and axial area.