Potamogeton pusillus var. tenuissimus Mertens & W.D.J. Koch

Potamogeton pusillus var. tenuissimus Mertens & W.D.J. Koch is a synonym sensu FNA Ed. Comm., 2000 of:

Potamogeton berchtoldii Fieber subsp. berchtoldii, an accepted subspecies name sensu WCSP.