This species is endemic to the Seychelles. The subspecies P. a. astriata occurs on the Mahé group (including Mahé itself, Silhouette, St Anne, Cerf and other nearby islands). The subspecies P. a. semicarinata occurs on the Praslin group (including Praslin itself, and also Aride, Cousin, Cousine, Curieuse, Grande Soeur and La Digue). Animals from Silhouette and Frégate have not been assigned to subspecies. It occurs from sea-level up to 500 m.