Isoëtes sabatina ( Isoëtaceae Lycopodiophyta ), a new aquatic species from central Italy.

The new speciesIsoëtes sabatinais described and illustrated. Morphological, anatomical, and ecological characters are given. It differs from the similarI. echinosporaby several characters, such as megaspore ornamentation and size, microspore size, velum extension and form, and also for its ecology. A table showing the main differential characters of the new species compared with those of the other European aquatic species is presented. So far, the species is known from a single locality (Bracciano Lake, central Italy), having a peculiar ecology and within the Mediterranean bioclimate. [ABSTRACT FROM PUBLISHER]