Author: Undescribed

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 10 mm

Sightings: Sunshine Coast

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Ceratosoma sp. 02  Undescribed

An undescribed species of Ceratosoma showing similar attributes to our Ceratosoma sp. 01 but also certain differences.

Ceratosoma sp. 2 (Gosliner et al, 2008) = Ceratosoma sp. 1 (Gosliner et al, 2018) This species has been sequenced to belong in Ceratosoma genus (Johnson & Gosliner, 2012). Both our Ceratosoma sp. 01 and Ceratosoma sp. 02 have similar external characteristics to that species.

These species have long been thought to belong in Noumea, now Verconia, due to the similarity in appearance of their mantle and none of which were examined internally. Some of these include a selection under Noumea? sp. 2 by Rudman, 2000 on the Sea Slug Forum and Coleman, 2008 p. 190, records a Glorious Noumea and a Mauve Noumea.

The shape of the dorsum of our Ceratosoma sp. 02 is flared and rounded both anteriorly and posteriorly such that the mid-section appears quite narrow in comparison, when crawling. As the mantle edge flares around the gill pocket it does not finish as a natural curve but extends posteriorly forming a small extension, just behind the gill, that is slightly cupped. The mantle is translucent but carries three distinct longitudinal and parallel yellow lines. The two outermost commence at the sides of the gill pocket and run anteriorly before stopping well short of the rhinophores. The central line commences well forward of the gill pocket and runs anteriorly before bifurcating just posterior to the rhinophores, both parts then continuing between the rhinophores to finish just anterior to them.

The entire mantle margin is pale yellow. A submarginal band of white lies immediately inside the yellow margin but is incomplete anteriorly from just posterior to the rhinophores. There are regularly spaced intense pink spots/dashes lying in the white submarginal band and also continuing around the anterior where the white submarginal band is lacking. Posteriorly where the mantle forms a small extension there is a single large pink spot.

The rhinophore stalks are translucent and the lamellate clavi are yellow for the proximal two thirds with the distal third being brown. The gill pocket appears slightly raised with the gills being translucent with some yellow pigment.

The sides of the body carry three longitudinal yellow lines of the same intensity as the lines on the dorsum. The foot is translucent with a few small scattered white spots. The tail is yellow dorsally.

David A. Mullins – January 2021

References:

– Rudman, W. B., (2000, April 1) Noumea? sp. 2. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/noumsp2 and associated messages.

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

– Gosliner, T. M., Behrens, D. W. & Valde ́s, A ́. (2008) IndoPacific Nudibranchs and Sea Slugs. Sea Challengers/California Academy of Sciences.

– 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.