The iguanas on Saba and Montserrat were formally known as melanistic Common Green iguanas (Iguana iguana). They have, however, been given their own species status and are now known as Iguana melanoderma.
Breuil, M.; Schikorski, D.; Vuillaume, B.; Krauss, U.; Morton, M.N.; Corry, E.; Bech, N.; Jelić, M.; Grandjean, F. (2020). "Painted black: Iguana melanoderma (Reptilia, Squamata, Iguanidae) a new melanistic endemic species from Saba and Montserrat islands (Lesser Antilles)".ZooKeys. 926: 95–131.
Link to the scientific article: https://zookeys.pensoft.net/article/48679/