Author: (Pruvot-Fol, 1930)

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 75 mm

Sightings: Sunshine Coast

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Goniobranchus kuniei (Pruvot-Fol, 1930)

The combination of colours and pattern in many of the Chromodorididae nudibranchs are a delight to observe and Goniobranchus kuniei is no exception. In this instance there is no doubt that the bold patterning combined with the subtle shading of complimentary hues both serve to contribute to its elegant presentation. I’m not ashamed to admit that I gasp every time I encounter this species and take plenty of time and images endeavouring to do justice to the display.

Goniobranchus kuniei has a broad oval shape to the mantle that overhangs the body considerably. The mantle margin carries three bands of colour. The outermost is thin and a very dark purple, the middle band is wider and of a lighter shade of purple while the innermost is also wide but of a darker purple than the middle band. This innermost band seems to be the most variable in colour among specimens at times tending almost to maroon. The middle and inner bands are not well defined tending to diffuse along their margins. Inside the third band the mantle colour is a broad golden yellow while the central-most portion is brown with an irregular edge created by intruding scallops of the golden yellow region. There are variations on this common theme with the brown region sometimes presenting instead as a broad band encircling the rhinophores and gills and having a central golden yellow region. The mantle margin colours are replicated on the ventral surface with the rest of the mantle underside, body wall and tail being cream (or a pale golden yellow). The most distinctive feature is the very dark purple to black spots of fairly regular size, shape and distribution, located in the yellow and brown region of the mantle, underside and even the tail (rarely as rings). These dark purple spots are surrounded by a lighter purple to white ring. Where the purple spots are located in the central brown region the encircling purple to white ring may itself be surrounded by a broader yellow ring. Sometimes a specimen may also have several smaller spots that are maroon rather than purple located more so towards the mantle margin.

The rhinophores arise from slightly raised translucent pockets into which they can withdraw. The stalk of the rhinophore is translucent whilst the clavus colour may vary from light yellow to light orange with a white tip. The clavus bears very fine lamellae. The gills are simple and described by Rudman as sub-quadrangular in shape. This refers to the cross-section having different sized surfaces and rounded corners. Arising from two opposite sides are the brown respiratory lamellae. The other two faces (anterior and posterior) are opaque white. When fully deployed the gill is large, spreading across a good half of the mantle width and the anal papilla is discernible in the centre. The entire gill can be withdrawn into a pocket beneath the mantle surface.

Goniobranchus kuniei is known to raise and lower its entire mantle edge in a single movement creating a dish-like shape to the mantle and exposing its foot and oral tentacles. It may also vary this by raising just the anterior or posterior portion separately or the whole mantle edge as a wave from front to back.

There are a number of similar looking species: Hypselodoris tryoni, narrow purple mantle margin and narrow elongated body shape; Goniobranchus leopardus, narrow purple mantle margin and most often broken irregular rings rather than spots; Goniobranchus geminus, a four-coloured mantle margin, the outermost white, plus it has an Indian Ocean distribution.

As with all the Chromodorididae nudibranchs Goniobranchus kuniei feeds upon sponges. It has been recorded feeding on Chelonaplysilla violacea a Darwinellidae species of sponge that is believed to be the exclusive prey of at least twelve related species of Goniobranchus some of which have similar colour patterns and in some cases the mantle flapping display as well.

The spawn of Goniobranchus kuniei is creamy orange in colour and laid as an upright spiral of at least two whorls. Extra-capsular yolk is present in the spawn mass and it is the presence of these as dark orange spots that gives the spawn the impression of being orange. The hatched veligers have planktonic development.

Goniobranchus kuniei has a wide tropical west and central Pacific distribution.

Originally described from New Caledonia as: Chromodoris kuniei. The author, Pruvot-Fol, apparently never deposited a holotype however a neotype has been designated and is held in the Paris Museum.

The Chromodorididae review by Johnson & Gosliner, (2012) transferred this species to the resurrected, “rescued from synonymy”, Goniobranchus genus. Pruvot-Fol also described another species – Glossodoris ransoni – from a single preserved specimen that was without any colour however the description of this species caused Rudman, (1987) to synonymize it with Chromodoris (Goniobranchus) kuniei.

David Mullins – July 2020

References:
– Rudman, W. B. (1984) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: a review of the genera. Zoological Journal of the Linnean Society 81: 115-273.

– Willan, R.C. & Coleman, N. (1984). Nudibranchs of Australia, Neville Coleman, AMPI: 20-21 (Species #45)

– Rudman, W. B. (1987) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Chromodoris epicuria, C. aureopurpurea, C. annulata, C. coi and Risbecia tryoni colour groups. Zoological Journal of the Linnean Society 90: 305-407.

– 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.

– Rudman, W. B., (1999 January 22). Chromodoris kuniei Pruvot-Fol, 1930. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/chrokuni and associated messages.

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

– Wilson, N. G. & Lee, M. S. Y. (2005). Molecular Phylogeny of Chromodoris (Mollusca: Nudibranchia) and the identification of a planar spawning clade. Molecular Phylogenetics and Evolution, 36, 722–727.

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

– Turner, L. M. & Wilson, N. G. (2008). Polyphyly across oceans: a molecular phylogeny of the Chromodorididae (Mollusca, Nudibranchia). Zoologica Scripta 37: 23–42.

– 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)

– This Species Profile has been modified from a previously published article in Dive Log Magazine’s – Critter ID with NudiNotes Column, Issue: #380 (March 2020): 14 by David A. Mullins.