SAGARITIS was a Naiad and Dryad Nymph of the River Saggarios (Sangarius) in Phrygia who had an affair with Attis, the young consort of the goddess Kybele (Cybele). When the goddess learned of their relationship she slew the Nymphe and drove Attis to castrate himself.
SAGARI′TIS, a nymph in whose embraces Attis became faithless to Cybele; the goddess avenged the wrong done to her by causing the tree with which the nymph's life was connected, to be cut down. (Ov. Fast. iv. 229.)
Source: Dictionary of Greek and Roman Biography and Mythology.
Ovid, Fasti 4. 222 ff (trans.Boyle) (Roman poetry C1st B.C. to C1st A.D.) :
"A woodland Phrygian boy, the gorgeous Attis, conquered the towered goddess [Rhea-Kybele] with pure love. She wanted to keep him as her shrine's guardian, and said, ‘Desire to be a boy always.’ He promised what was asked and declared, ‘If I lie, let the Venus [Aphrodite] I cheat with be my last.’ He cheats, and in the Nympha Sagaritis stops being what he was: the goddess' wrath punished him. She slashes the tree and cuts the Naiad down. The Naiad dies: her fate was the tree's."
- Ovid, Fasti - Latin Epic C1st BC - C1st AD