Either way, there are more than 150 species of Perizoma currently known, with a generally Northern Hemisphere distribution (e.g. 14 occurring in Europe), and new ones still being described occasionally. Many of them are called rivulets ("the" rivulet is P. affinitata specifically), while others are known as "carpets", a common name for Larentiinae in general.
One of its junior synonyms is Emmelesia, proposed by J.F. Stephens no less than three times – once validly in 1829, and within the next two years twice more invalidly. Another invalid name of Perizoma – Opisogonia, chosen by G.A. Herrich-Schäffer in 1856 – had already been used by the same author the year before for a different geometer moth genus.
Read more about Perizoma: Selected Species