Complex sentence: Collega is best known from Pliny the Younger's account in his "Epistulae" about the corruption trial of Marius Priscus, the former proconsular governor of Africa.
Split into simpler sentences: Collega is best known from Pliny the Younger's account in his "Epistulae". Collega participated in the corruption trial of Marius Priscus, former proconsular governor of Africa.