The nominal subspecies of I. velata has a Mediterranean-Atlantic distribution, being present in Sardinia and in some regions of peninsular Italy. The life-cycle can be spent part in water, part on moist to dry soil. It grows in ponds and ephemeral pools that are flooded in winter and spring, but are generally dry in the summer, usually on acid substrates, from sea level to about 1000 m. In Sardinia it is found in the intermediate belt of the temporary ponds. It is indicated in the Regional Red Lists as a vulnerable species (Conti et al., 1997). The genus name derives from the Greek 'isos' (equal) and 'ethos' (year), in reference to the leaves that persist throughout the year; the species name refers to the macrosporangia, which are almost completely covered by a kind of veil. Sporulation period: April to August.

Italian name(s): Calamaria tegulense (Italia), Calamaria velata (Italia), Isoete tegulense (Italia), Isoete velata (Italia).