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Chromodoris elisabethina

Species Profile

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Chromodoris elisabethina

Author: Bergh, 1877

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 70 mm

Sightings: Sunshine Coast

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Chromodoris elisabethina Bergh, 1877

The mantle shape is elongate-oval overhanging the foot, pinching somewhat at the midpoint and flaring out again in the region of the gill before tapering to round off posteriorly. The profile is low but rising slightly around the gill pocket. The tapered tail section of the foot is usually exposed beyond the posterior edge of the mantle. 

The medial region of the mantle is “sky” blue, sometimes darker, and completely bordered by a substantial black band looping around the mantle to enclose the rhinophores (sometimes a gap anterior to the rhinophores) and gill. Outside of the black band is a thin white line followed by a broad yellow/orange band. A fine white line exists on the very thickness of the mantle edge. The black looping band sometimes thickens approximately at the halfway point down the mantle. A thin (usually) black line runs longitudinally down the midline from anterior to and between the rhinophores to the gill pocket and may be continuous or broken. The gill pocket base carries a u-shaped black line that wraps posteriorly and runs anteriorly on each side, sometimes extending some distance and even linking up with additional black continuous or broken lines that extend posteriorly from the rhinophores. In some specimens a distinctive darker patch exists on the mantle between both sides of the looping black band at the pinch-in region. Dark patches are evident posterior to the rhinophores. The foot replicates the colouration of the mantle with one to three black lines.

The lamellate rhinophore clubs are yellow/orange, sometimes quite dark with translucent yellow stalks. The slightly raised rhinophore pockets and their rims are yellow/orange.  The simple gill is arranged in a horseshoe shape around the anus, open posteriorly. Colour of the up to 10 gill branches is yellow/orange to even a vivid red. The rim of the gill pocket is yellow/orange.

The spawn has been identified as a cream coloured planar (flat) spiral of up to 5 whorls laid upon the substrate. There is no extra-capsular yoke present. The larvae hatch as planktonic veligers.

Chromodoris elisabethina is a spongivore upon species of Thorectidae sponges, identified thus far as Petrosaspongia spp. and Luffariella sp.

Distribution is broadly tropical Indo-West Pacific – as far north as Okinawa and as far west as the Seychelles. On the east coast of Australia as far south as Solitary islands and Lord Howe Island. On the west coast of Australia as far south as Carnarvon.

A tortured history
Bergh, 1875 published a list of Chromodoris species that included the following: Chr. elisabethina. Bgh. n. sp. (translated as Chromodoris elisabethina. Bergh. nova species.) however. no description whatsoever was included of that species. Although this was the first use of that name, without an accompanying description it is considered a nomen nudum (naked name) meaning the name has no status and therefore neither does the publishing date in relation to priority. Later, in Bergh,1877, he published a description of Chromodoris elisabethina so the date of species authorship is taken as 1877. That description was based upon a preserved specimen (lacking any colour other than the black lines) with a black and white line drawing but no colour description. That lack of any colour description or colour illustration was to create long running confusion between C. elisabethina and other black-lined Chromodoris species, even by Bergh himself. For example, Bergh, 1905 published a further description under the name of C. elisabethina but used an illustration of what eventually became known as Chromodoris lochi Rudman, 1982. Bergh’s confused labelling of illustrations and tangled nomenclature (including also that of C. annae and C. quadricolor) misled Rudman, 1977 into synonymising C. annae with C. elisabethina and using the wrong specimens (later described as C. lochi) to redescribe C. elisabethina. Interestingly, although Rudman, 1977 gave a colour description based on colour photographs and transparencies, none were included in the paper. All of this was finally corrected in Rudman, 1982.

Rudman, 1982 states: “No colour description of C. elisabethina has appeared in the literature.” That paper published the first colour image of Chromodoris elisabethina together with a description that finally  differentiated between Chromodoris elisabethina, C. annae, C. quadricolor and C. lochi, around which so much confusion had been created by Bergh and inadvertently by Rudman, but fortunately untangled by Rudman. The next published image and description of C. elisabethina was by Willan & Coleman, 1984.

The specific epithet has often been misspelt in the past as elizabethina (with a z) instead of the correct elisabethina (with a s).

Above: A pair of Chromodoris elisabethina nudibranchs move and feed across the substrate.

David A. Mullins – December 2023

References:
– Bergh, L. S. R. (1875). Neue Nacktschnecken der Sudsee. III. Journal de Museum Godeffroy, 3(8): 53-100, [185-232], Pls.7-11.

– Bergh, L. S. R. (1877). Malacologische Untersuchungen. In: C.G. Semper, Reisen im Archipel der Philippinen, Wissenschaftliche Resultate, 11: 429-494, Pls.54-57.

– Bergh, L. S. R. (1905). Die Opisthobranchiata der Siboga Expedition. Siboga Expeditie Report, 50: 1 248.

– Rudman, W . B. (1977). Chromodorid opisthobranch Mollusca from East Africa and the tropical West Pacific. Zoological Journal of the Linnean Society. 61: 351-397.

– Rudman, W. B. (1982) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Chromodoris quadricolor, C. lineolata and Hypselodoris nigrolineata colour groups. Zoological Journal of the Linnean Society, 76: 183-241.

– Willan, R. C. & Coleman, N. (1984). Nudibranchs of Australia, Neville Coleman, AMPI: 24-25.

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

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

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

– Herve J. (2010). Guide des Nudibranches de Nouvelle-Caledonie et autres Opisthobranches, Editions Catherine Ledru.

– 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.

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

Other Sea Slugs in this Family (sighted)

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