Author: (Kelaart, 1858)

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 30 mm

Sightings: Sunshine Coast, Capricorn/Bunker Group GBR; Anilao Philippines, Bali Indonesia

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Goniobranchus preciosus (Kelaart, 1858)

In November of 2021 The Team undertook a live-aboard dive trip to the Capricorn Group, Great Barrier Reef. During that trip we recorded a specimen of Goniobranchus preciosus at Tryon Island. Upon return, this find had us thinking that perhaps some specimens we had found previously on the Sunshine Coast, that we had identified as Goniobranchus verrieri, might actually be Goniobranchus preciosus. A review of our data and closer examination of our G. verrieri images uncovered a number of misidentified examples.

Rudman’s 1985 description tells us that in Goniobranchus preciosus the mantle overhangs the sides and only a small posterior portion of the foot is left exposed. The smooth mantle is creamy-white and may carry diffuse spotting of red or brown sometimes creating a mottled appearance where parts of the mantle are translucent. There are three bands to the mantle margin – outermost – bluish-white, central – deep red, and innermost – orange/yellow. These bands are of similar width. (Our observations reveal that sometimes the outermost bluish-white band may be a little narrower.) Some of our specimens also exhibit a blue border to the tail similar to that of Gosliner et al, 2018, (NSSI 2nd Edition), P.152 bottom right image.

Since this Species Profile was written and uploaded in January 2022, a new paper has been published, Soong et al, 2022, where the white Goniobranchus nudibranchs with marginal bands were studied. One of those included in the study was Goniobranchus preciosus.

Soong et al 2022 have identified four morphotypes of this species, designated A, B, C & D.

The generalised common characteristics for all four morphotypes include:
– White body, oval-elongate shape, mantle always with low tubercles on the notum.
– Three marginal mantle bands: outermost blue then deep red then yellow.
– Rhinophores are reddish brown with pigment extending down onto the stalks, white edges to the lamellae.
– Gill held erect, reddish brown in colour with white lines on rachis.

The four morphotypes are differentiated as follows:
– A: Translucent creamy white – fine orange spots/blotches; thin bluish-white band, thicker deep red band, then yellow orange band; gill & rhinophores translucent red, white edges.
– B: Translucent pale yellow – brown spots/blotches; opaque bluish white, then irregular red band, then yellow orange band – all bands similar width; gill & rhinophores translucent brown, opaque cream edges.
– C: Opaque white; bluish-white band thin, thicker red and yellow bands; Gill & rhinophores translucent red opaque white edges.
– D: Translucent creamy white – densely speckled orange spots; thin opaque bluish white band, irregular deep red & yellow bands, all = width; gill & rhinophores translucent red with opaque white edges.

Distribution: Eastern Indian Ocean, Western and Central Pacific Ocean

This species has had a confused history due mainly to the somewhat ambiguous original description by Kelaart and a subsequent, “apparently”, inaccurate illustration of Kelaart’s published by Eliot, 1906. Rudman, 1985, undertook a redescription of this and similar looking species. Rudman states that the illustration of Doris preciosa published by Eliot: “… bears little relationship to Kelaart’s earlier description and should be considered inaccurate.” However Eliot had stated: “The drawings consist of figures of about 55 species of Nudibranchs made from life by Kelaart in Ceylon. Thirty-five of these figures are now reproduced.” These included Doris preciosa. What are we to make of this? Rudman is correct, the illustration does not reflect Kelaart’s description. So we are best to ignore it and make the most of the word picture instead. The type specimen of this species appears to be most likely lost to science.

Previously known as Chromodoris preciosa it is included in the species listed as having been sequenced and subsequently removed from Chromodoris and placed in Goniobranchus by Johnson & Gosliner, 2012.

Originally described as Doris preciosa.

David A. Mullins – January, 2022 (revised July 2023)

References:
– Kelaart E. F., (1858). Description of new and little known species of Ceylon nudibranchiate molluscs, and zoophytes. Journal of the Ceylon Branch of the Royal Asiatic Society. 3: 84-139.

– Eliot, C. N. E., (1906). On the nudibranchs of Southern India and Ceylon, with special reference to the drawings by Kelaart and the collections belonging to Alder & Hancock preserved in the Hancock Museum at Newcastle-upon-Tyne. Proceedings of the Zoological Society of London. 636-691

– Rudman, W. B., (1985). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Chromodoris aureomarginata, C. verrieri and C. fidelis colour groups. Zoological Journal of the Linnean Society. 83: 241-299.

– Rudman, W. B., (2000, July 2). Chromodoris preciosa (Kelaart, 1858). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/chroprec and associated messages.

– 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)

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

– Soong, G. Y., Bonomo, L. J., Reimer, J. D. & Gosliner, T. M. (2022). Battle of the bands: systematics and phylogeny of the white Goniobranchus nudibranchs with marginal bands (Nudibranchia, Chromodorididae). ZooKeys 1083: 169–210. https://doi.org/10.3897/zookeys.1083.72939