Diversity of the extinct land snail genus Chilonopsis of St Helena (Mollusca: Gastropoda: Achatinidae)

The extinct land snail genus Chilonopsis (Achatinidae) endemic to St Helena is revised, based on existing and new material collected during palaeontological investigations in 2022–2023. We recognise nine species, including one from the new material that was previously undescribed: Chilonopsis lanceoloideus sp. nov. We review the nomenclature of all species and confirm the recent, but largely overlooked, validation of C. aurisvulpina, and the correct spelling of C. melanioides. We designate lectotypes for C. aurisvulpina and C. subtruncatus and synonymise Bulimus relegatus Benson with the former. Two species were recorded alive in 1878 and 1884–86 (C. melanioides and C. turtoni), but neither have been found alive since; the others have only ever been found as subfossil material.