Actinocyclus papillatus
(Bergh, 1878)

Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: EUDORIDOIDEA
Family: Actinocyclidae

DISTRIBUTION

Tropical Indo-West Pacific

PHOTO

Upper: Coffs Harbour region, nothern New South Wales, December 1990. Photos: Bill Rudman [more detail to be added]. Lower:  Seogwipo. Bum islet, Jeju. Sth Korea. Depth: 26 m. Length: Approx. 100 mm. July 2005. Muddy. Photographer: Sung Han Cho.

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 synonym of A. papillatus is Sphaerodoris laevis var variegatus Eliot, 1904.

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. papillatus the body is covered with many large rounded tubercles. It ranges in colour depending on the shade of the brown background colour and the density of the cream white speckling scattered all over. Some animals are brown with little craemy speckling, while others are mainly cream white with only patches of the brown background colour showing through. In Valdes's review he describes 'a number of short, irregular, very densely arranged dark grey lines ...' and ' numerous white spots'. This is very dependent on how much white pigmentation is present in the specimen being observed. While the white spots are very obvious, the lines are only present in specimens with quite dense white pigmentation. This species grows to at least 10 cm 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 papillatus (Bergh, 1878). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/actipapi

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