Epyllion.

The word (from the Greek, 'little epic') was first used in the 19th century to describe classical poems that told a story whose subject was love, with mythological allusions and at least one major digression. The tradition dated from the time of Theocritus (d.250 BC); Peleus and Thetis by Catullus (d.c.54 BC) is a late Roman example. The term became applied to post-classical literature, especially the erotic treatment of mythological narratives in Renaissance poetry. Shakespeare's Venus and Adonis and Marlowe's Hero and Leander are major English examples. Thomas Lodge's Scillaes Metamorphosis (1589) and Francis Beaumont's Salmacis and Hermaphroditus (1602) minor ones.


Source:
The Cambridge Guide to Literature in English. Ian Ousby, Ed.
Cambridge, Cambridge University Press, 1998. 67.