Actinocyclus verrucosus
Ehrenberg, 1831

Suborder: DORIDINA
Family: Actinocyclidae


Tropical Indo-West Pacific.


Light colour form, Split Solitary Island, Coffs Harbour, nthn New South Wales, February, 1987. C152686. Photo: Bill Rudman

Until recently most specimens of Actinocyclus were identified as the single species Actinocyclus japonicus (Eliot, 1913) because of the difficulty in understanding earlier descriptions. Valdes (2002) reviewed the genus and has proposed we recognise two species, A. verrucosus and A. papillatus. The main synonyms of A. verrucosus are Sphaerodoris punctata Bergh, 1878, Sphaerodoris laevis Bergh, 1890, Sphaerodoris japonica Eliot, 1913  and Aldisa nhatrangensis Risbecia, 1956.

In general, the species of Actinocyclus have a tough leathery mantle, with a circlet of many short gills held in a cup-shaped arrangement similar to Hallaxa. In A. verrucosus  the body is covered with low rounded tubercles, a few of which are relatively large. It ranges in colour from a yellowish brown to a dark grey brown, almost black. In lighter specimens small dark specks can be seen scattered evenly over the dorsum. The large tubercles usually have a black or very dark grey patch at the tip, often surrounded by a much lighter ring.  It grows to at least 50mm in length.

  • Bergh, L. S. R. (1878) Malacologische Untersuchungen. In: C.G. Semper, Reisen im Archipel der Philippinen, Wissenschaftliche Resultate. Band 2, Heft 13: 547-601,Pls.62-65.
  • Ehrenberg, C. G. (1828 or 1831) Symbolae physicae seu
    icones et descriptiones animalium evertebratorum sepositis insectis quae ex itinere per Africam borealem et Asiam Occidentalem--novae aut illustratae redierunt.
    Decas 1 Mollusca.
  • Eliot, C. N. E. (1913) Japanese nudibranchs. Journal of the College of Science, Tokyo Imp. University, 35: 1-47. (Pls.1-2)
  • Risbec, J. (1956) Nudibranches du Viet-Nam. Archives du Museum National d'Histoire Naturelle Paris, 7 4, 1-34. (Pls. 1-22)
  • Valdés, A. (2002) Review of the genus Actinocyclus Ehrenberg, 1831 (Opisthobranchia: Doridoidea). The Veliger 45: 193-202.
Authorship details
Rudman, W.B., 2005 (August 4) Actinocyclus verrucosus Ehrenberg, 1831. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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