Found throughout the tropical Indo-West Pacific.
Upper Photo: A. verrucosus
Lower Photo: A. papillatus
Upper: Light colour form, Split Solitary Island, Coffs Harbour, nthn New South Wales, February, 1987. Lower: Dark colour form, Coffs Harbour region, northern NSW, December, 1990. Photos: Bill Rudman.
Note added 4 August 2004: Actinocyclus japonicus is considered a synonym of A. verrucosus. Two species are now recognised, the other being A. papillatus. Previously, both species were identified as A. japonicus.
Rudman, W.B., 1998 (July 8) Actinocyclus japonicus (Eliot, 1913). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/actinjap