Rhythm is a dancer

It’s a bad pain day, so I was up early reading when I came across this passage from the anonymous Stoic treatise Epitoma disciplinarum:

Rhythm is believed to be named after Rhythmonius, the son of Orpheus and Idomena, an Ismarian Nymph, as Nicocrates records in the book he wrote About Music. He records that the brother of Rhythmonus was Hymenes; and the son of Rhythmonius and Chloris, daughter of Tiresias, was Periclymenus, who first sang the deeds of heroes in musical songs. (10.1)

An Ismarian Nymph, you say? This would be another example of Orpheus mating with a Sovereignty Goddess. Interesting.