The two terms used to have different meanings, but must be today considered synonyms.

However, the latter is sometimes considered a junior synonym of former.

It was considered a synonym of Lasionycta for some time.

All other species are considered synonyms of the type.

It is considered a synonym of Xystrota by some sources.

Today this is considered a junior synonym of P. foxii.

It is considered a synonym of Perizoma by some authors.

Many of these supposed fossilized species are now considered junior synonyms.

This species is now considered a junior synonym of A. platyrhynchus.

Root can be considered a synonym for base in the arithmetical sense.