The diagnosis of two species of marine hypotrich ciliates: Amphisiella aren
icola and A. ovalis is shown. These species were described previously by th
e same authors, as well as the statistical analysis of their biological fea
tures and the comparison with the most similar species. Since the diagnosis
of both species did not appear in the previous work, these diagnosis are i
ncluded, in order to observe the rules of the International Code of Zoologi
cal Nomenclature.