Passage 8.27.11
χρόνον δὲ οὐ μετὰ πολὺν Ἀριστόδημος Μεγαλοπολίταις ἀνέφυ τύραννος, Φιγαλεὺς μὲν γένος καὶ υἱὸς Ἀρτύλα, ποιησαμένου δὲ αὐτὸν Τριταίου τῶν οὐκ ἀδυνάτων ἐν Μεγάλῃ πόλει· τούτῳ τῷ Ἀριστοδήμῳ καὶ τυραννοῦντι ἐξεγένετο ὅμως ἐπικληθῆναι Χρηστῷ. ἐπὶ τούτου τυραννοῦντος ἐσβάλλουσιν ἐς τὴν Μεγαλοπολῖτιν στρατιᾷ Λακεδαιμόνιοι καὶ τοῦ βασιλέως Κλεομένους ὁ πρεσβύτατος τῶν παίδων Ἀκρότατος· ἐγενεαλόγησα δὲ ἤδη τά τε ἐς τοῦτον καὶ ἐς τὸ πᾶν γένος τῶν ἐν Σπάρτῃ βασιλέων. γενομένης δὲ ἰσχυρᾶς μάχης καὶ ἀποθανόντων πολλῶν παρʼ ἀμφοτέρων κρατοῦσιν οἱ Μεγαλοπολῖται τῇ συμβολῇ· καὶ ἄλλοι τε διεφθάρησαν Σπαρτιατῶν καὶ Ἀκρότατος, οὐδέ οἱ τὴν πατρῴαν παραλαβεῖν ἐξεγένετο ἀρχήν.
Not long afterwards Aristodemus rose up as tyrant over the Megalopolitans. He was of Phigalean descent, the son of Artylas, and owed his elevation to Tritaïeus, one of the most influential men in Megalopolis. Yet, despite his tyrannical rule, it happened that he earned the surname "the Good." While Aristodemus held power, the Lacedaemonians invaded Megalopolitan territory under Acrotatus, the eldest son of King Cleomenes. I have previously detailed the genealogy both of this Acrotatus and the entire dynasty of Spartan kings. A fierce battle ensued, and many fell on both sides; nevertheless, the Megalopolitans prevailed in the encounter. Among the Spartans killed was Acrotatus himself, who thus never succeeded to his ancestral throne.