See Parthenius

"ὃς μὲν ἦν οὐκ ἐδήλου, θετταλίζων δὲ τῇ φωνῇ τὸν Ἱππαρῖνον ἔφησεν ἀπεκτονηκέναι"

Refers to the Thessalian dialect (imitation of).