Tragedy in Ancient Sikyon (Sources)

I must not forget to explain that (the tyrant) Kleisthenes chose Melanippos as the person to introduce in Sikyon, because he was a bitter enemy of Adrastos, having killed both his brother Mecistes, and Tydeus his son-in-law. After settling him in his new shrine, he transferred to him the religious honors of sacrifice and festival which had previously been paid to Adrastos. The people of Sikyon had always regarded Adrastos with great reverence, because the country had once belonged to Polybos, his maternal grandfather, who died without an heir and left the kingdom to him. One of the most important of the tributes paid him was the tragic chorus, or ceremonial dance and song, which the Sikyonians celebrated in his honor; normally, the tragic chorus belongs to the worship of Dionysos; but in Sikyon it was not so -- it was performed in honor of Adrastos, treating his life-story and sufferings.
Kleisthenes, however, changed this: he transferred the choruses to Dionysos, and the rest of the ceremonial to Melanippos.

Other Sources

1. Thespis: Of the city of Ikarios in Attica, the sixteenth tragic poet after the first tragic poet, Epigenes of Sikyon, but according to some second after Epigenes. Others say he was the first tragic poet. In his first tragedies he anointed his face with white lead, then he shaded his face with purslane in his performance, and after that introduced the use of masks, making them in linen alone. He produced in the 61st Olympiad (536/5-533/2 BC). Mention is made of the following plays: Games of Pelias or Phorbas, Priests, Youths, Pentheus. (The Suda lexicon)

2. "Nothing to do with Dionysos". When Epigenes the Sikyonian made a tragedy in honor of Dionysos, they made this comment; hence the proverb. A better explanation: Originally when writing in honor of Dionysos they competed with pieces which were called satiric. Later they changed to the writing of tragedy and gradually turned to plots and stories in which they had no thought for Dionysos. Hence this comment. Chamaeleon writes similarly in his book on Thespis. (The Suda lexicon)

3. "Nothing to do with Dionysos". When, the choruses being accustomed from the beginning to sing the dithyramb to Dionysos, later poets abandoned this custom and began to write "Ajaxes" and "Centaurs". Therefore the spectators said in joke, "Nothing to do with Dionysos." For this reason they decided later to introduce satyr-plays as a prelude, in order that they might not seem to be forgetting the god. (Zenobius V.40)

4. When Phrynichus and Aeschylus developed tragedy to include mythological plots and disasters, it was said, "What has this to do with Dionysos?" (Plutarch, Symp. Quaest.)

Comedy

    "Μούσης νουθεσίην φιλοπαίγμονος εύρετο Βάκχος
     ώ Σικυών, εν σοί κώμον άγων Χαρίτων;
     δή γάρ έλεγχον έχει γλυκερώτατον, έντε γέλωτι
     κέντρον χώ μεθύων αστόν εσωφρόνησεν".
     (Ονέστης, Παλατ. Ανθ., ΧΙ, 32)

Tragedy

Herodotus: History Chapter V.67

Other Sources

Comedy

Herodotus: History
Chapter V.67