The introduction of Polygyra cereolus (Megerle von Mühlfeldt, 1816) on Guadeloupe is recorded in a paper by Laurent Charles (2014). The material was collected in 2013, but may have occurred already for some time on the island; new introductions in a fauna may remain unnoticed if the species is relatively small.
Charles, L., 2014. Signalement de Polygyra cereolus (Megerle von Mühlfeldt, 1816)(Mollusca: Gastropoda: Polygyridae) à la Guadeloupe (Petites-Antilles). – MalaCo 10: 5-6. (Available at http://www.journal-malaco.fr/documents/MalaCo_2014_10_Charles_5_6.pdf)