On the Canonization of St. Poeman the Great and the Origin of His Epithet?

Often quoted in the "Sayings or the Desert Fathers," St. Poeman is venerated in the Roman Catholic Church, as well as some of the Eastern Orthodox churches. QUESTION: Was St. Poeman ever formally canonized in the Roman Catholic Church; i.e., solemnly declared so by a Pope? If so, by whom? Also, how did the epithet, **"the great"**, get attributed to him?