Author: (Ruppell & Leuckart, 1830)

Order: Nudibranchia  Family: Gymnodorididae

Maximum Size: 60 mm

Sightings: Whitsundays

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Gymnodoris impudica (Ruppell & Leuckart, 1830)

A large fast-moving voracious gymnodorid nudibranch that preys upon other nudibranchs usually by following their slime trail. 

Gymnodoris impudica has a body high in profile, highest at the region of the gill and elongate when on the move. Specimens that have recently fed appear particularly engorged. The body is white to cream in colour but covered in many large low orange pustules – sometimes presenting as a ring with only the base orange and the centre cream coloured. There is an orange band to the edge of the foot. Rhinophores are somewhat bulbous and orange in colour. The gill forms a complete circle around the anus and is white with varying amounts of orange. Colour can range from pale orange to red.

Spawn is laid on the substrate as a bright orange spiral, on edge.

Widespread throughout the Indo-Pacific region including the Red Sea.

There is a similar undescribed species. That species has a body that is more translucent, and the large spots consist of a fine orange ring infilled with small orange specks and a white centre. There is no orange band to the foot and the rhinophores are cream in colour.

– Originally described as: Doris impudica Ruppell & Leuckart, 1830.
– Gymnodoris rubropapulosa (Bergh, 1905) is a synonym. (Yonow, 2008)
–  This is the Gymnodoris rubropapulosa (Bergh, 1905) of the Sea Slug Forum, 2000; Debelius & Kuiter, 2007; Coleman, 2008  & NSSI, 2018.

David A. Mullins – May 2024

References:
– Rüppell, E. & Leuckart, F. S. (1828-1830). Mollusca. In: Atlas zu der Reise im nordlichen Afrika von Eduard Rüppell. Neue wirbellose Thiere des Rothen Meeres. Frankfurt, H. L. Brönner. pp. 15-22, pls 4-6 [1828]; pp. 23-47, pls 7-12 [1830].

– Bergh, L.S.R. (1905). Die Opisthobranchiata. Siboga Expeditie Report, 50: 248pp., Pls 1-20.

– Rudman, W.B., (2000, December 29) Gymnodoris rubropapulosa (Bergh, 1905). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/gymnrubr and associated messages.

– Debelius, H. & Kuiter, R. H. (2007) Nudibranchs of the World. IKAN-Unterwasserarchiv, Frankfurt.

– Yonow, N. (2008). Sea Slugs of the Red Sea. Pensoft Publishers.

– Coleman, N. (2008). Nudibranchs Encyclopedia. Neville Coleman’s Underwater Geographic Pty Ltd, Springwood, Qld. Pp311 & 312

– Yonow N. (2011) Results of the Rumphius Biohistorical Expedition to Ambon (1990). Part 15. The suborder Doridina (Mollusca, Gastropoda, Opisthobranchia, Nudibranchia). Zoologische Mededelingen 85(17): 905-956.

– Gosliner, T. M., Valde ́s, A ́. & Behrens, D. W. (2018). Nudibranch & Sea Slug Identification – Indo-Pacific, 2nd Edition. New World Publications, Jacksonville, Florida, USA.