摘要

A new monoraphid marine species, Achnanthes pseudolongipes, is described. The structure of its valves and girdle resemble those of A. longipes Agardh, as well as the shape of the plastid. However, A. longipes has biseriate striae on both valves, whereas A. pseudolongipes has uniseriate striae on the raphid valve and biseriate (or triseriate) on the araphid valve. In the genus Achnanthes sensu strict, only A. pseudolongipes possesses both uniseriate and biseriate striae. The number of striae between costae is one of the most effective features of the valve for the identification of taxa in the genus Achnanthes Sensu stricto.