Verslag sieralgenbemonstering De Diepen, 11 september 2021

De Diepen was visited in 2021 during the annual excursion of the Dutch desmid working group. This area, located at the base of the moraine south of Nijmegen, is fed by alkaline-rich groundwater. It used to be a varied area with swamps and fens, and very rich in rare species of desmids. After reclamation for agriculture, nothing was left. A few years ago it was attempted to restore the former situation by removing the top layer. In this part of the report of the excursion, some taxonomically interesting and unclear taxa are discussed, among which Closterium acutum var. latius, Cosmarium cf. costatum and C. cf. fictopraemorsum.