Author: (Angas, 1864)

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 25 mm

Sightings: Sunshine Coast

Goniobranchus daphne (Angas, 1864)

Goniobranchus daphne is a small chromodorid nudibranch (up to 45 mm) with a limited Australian distribution. Goniobranchus daphne has only been reported from Central and Southern Queensland and the coast of New South Wales as far south as Jervis Bay, and Lord Howe Island. It does not appear in Burn’s 2006 Checklist of Opisthobranchia of Victoria and Bass Strait. There are a number of similar looking nudibranchs with red-spotted mantles and red-yellow margins occupying the same geographic distribution however Goniobranchus daphne can be identified from the following combination of coloured features.

The broad mantle is a semi-translucent white, sometimes tending to cream, with numerous small red spots or speckles. It has a yellow sub-marginal band on the inside of its red mantle margin. Close examination reveals a fine translucent band to the very edge. The foot, which extends past the posterior edge of the mantle, is white above and below without any other colouration and this can be considered a characteristic distinction from similarly coloured relatives. The rhinophores have a red clavus and a translucent white stalk. The simple gills are arranged in a circle around the anus and are uniformly red in colour. Defensive mantle glands, white in colour, containing distasteful or poisonous substances obtained/metabolized from their food source, are distinctive sub-marginally. It has been observed that the further north this species is found the colours tend to be more vivid.

The spirally laid egg ribbon, most usually of two to two and a half whorls, is laid upright on edge, yellow in colour and the egg capsules are, relatively speaking, quite large. This together with its limited distribution has led to the suggestion, Rudman, (2006) Sea Slug Forum, that this species may have lecithotrophic development, where the larvae have a short planktonic stage. However, Wilson, (2002) has observed the hatchlings of Goniobranchus daphne becoming planktotrophic veligers.

The prey of Goniobranchus daphne is thought to be quite specific, feeding upon the sponge Chelonaplysilla violacea. Some other species that also feed upon this sponge have a comparable colour pattern.

The red-spotting on the white mantle dorsum gives this species a somewhat similar appearance to a number of other dorids including Goniobranchus splendidus and Mexichromis festiva that have a somewhat equivalent distribution. This similarity is speculated to be an example of aposematic mimicry whereby a group of animals display similar colour and pattern in order to spread the load of warning (“teaching”) potential predators, mainly fish, that they possess distasteful/poisonous mantle glands.

Goniobranchus daphne has been found in both intertidal and subtidal habitats most commonly in coastal waters and estuaries due, no doubt, to being the preferred habitat of their sponge prey.

Previously known as: Chromodoris daphne, prior to that Glossodoris daphne

Originally described as: Goniodoris daphne

References:
– Angas, G. F. (1864). Description d´éspèces nouvelles appartenant à plusieurs genres de mollusques nudibranches des environs de Port-Jackson (Nouvelle-Galles du Sud), accompagnée de dessins faits d´après nature. Journal de Conchyliologie. series 3(12): 43-70.

– Allan, J. (1947). Nudibranchia from the Clarence River Heads, north coast, New South Wales. Records of the Australian Museum, 21: 433- 463.

– Thompson, T. E. (1972). Chromodorid nudibranchs from eastern Australia (Gastropoda, Opisthobranchia). Journal of Zoology, London, 166: 391-409.

– Rudman, W.B. (1983) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Chromodoris splendida, C. aspersa and Hypselodoris placida colour groups. Zoological Journal of the Linnean Society 78: 105-173.

– Rudman, W.B. (1991). Purpose in Pattern: the evolution of colour in chromodorid nudibranchs. Journal of Molluscan Studies, 57: 5-21.

– Marshall, J.G., Willan, R.C. (1999). Nudibranchs of Heron Island, Great Barrier Reef: A survey of the Opisthobranchia (sea slugs) of Heron and Wistari Reefs; Backhuys: Leiden, The Netherlands, 1999.

– Wilson, N.G. (2002) Egg Masses of Chromodorid Nudibranchs (Mollusca: Gastropoda: Opisthobranchia). Malacologia, 2002, 44(2): 289-305.

– Rudman, W.B. 2006 (Mar 27). Comment on Chromodoris daphne laying eggs by Leanne & David Atkinson. [Message in] Sea Slug Forum. Australian Museum, Sydney

– Burn, R. (2006). A checklist and bibliography of the Opisthobranchia (Mollusca: Gastropoda) of Victoria and the Bass Strait area, south-eastern Australia. Museum Victoria Science Reports 10: 1-42 (2006).

– Rudman, W.B., Bergquist (2007) A review of feeding specificity in the sponge-feeding Chromodorididae (Nudibranchia: Mollusca). Molluscan Research, 27(2): 60-88.

– Johnson, R.F., Gosliner, T.M. (2012). Traditional taxonomic groupings mask evolutionary history: A molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS One 7 (4): e33479.

– Nimbs, M.J., Smith, S.D.A. (2017). An illustrated inventory of the sea slugs of New South Wales, Australia (Gastropoda: Heterobranchia). Proceedings of the Royal Society of Victoria 128: 44-113.

– This Species Profile has been modified from:
– Opisthobranch of the Week, Week #752, Chromodoris daphne (15/08/2011), Mike Miller’s slugsite.tierranet.com by David A. Mullins
– A previously published article in Dive Log Magazine’s – Critter ID with NudiNotes Column, Issue: #345 (April 2017): 12 by David A. Mullins

David A. Mullins – March 2020