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Goniobranchus collingwoodi

Species Profile

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Goniobranchus collingwoodi

Author: (Rudman, 1987)

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 45 mm

Sightings: Sunshine Coast Australia, Anilao Philippines, Tulamben Bali Indonesia, Milne Bay PNG

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Goniobranchus collingwoodi (Rudman, 1987)

Some chromodorids just “pop” when the strobe light hits them, all those bright warning colours and patterns, and Goniobranchus collingwoodi is no exception appearing to sparkle with the white speck distribution on its mantle.

The body is elongate oval in shape with the mantle overhanging the body and foot considerably, apart from the tail where the posterior portion of the foot most often protrudes. It is a medium-sized nudibranch recorded up to 45 mm in length.

The central portion of the mantle from anterior to the rhinophores to just posterior to the gill is a translucent reddish-brown. Sometimes the reddish-brown will be patchy with the white background showing through. The intensity of the reddish-brown also varies considerably between specimens. Frequently, purple spots will be found evenly scattered in this region and the whole is covered with a fine white speckling, those on the purple spots creating a sparkling presentation. The appearance of that central mantle region is certainly diagnostic for the species. Although the mantle is essentially smooth in the majority of specimens there are some where the white showing through the reddish-brown is raised into a low tubercle in several places. The mantle margin carries an irregular purple line of varying width at times being reduced to just a series of spots or indentations. Inside of this is a broad white region that carries both purple and yellow spots, the yellow spots being denser and closer to the margin and the purple closer to the reddish-brown region sometimes situated in translucent scallops emanating from the reddish-brown. There is much variation, but in the same general theme, in the presentation of the mantle some no doubt related to localities. The foot is white and carries the same arrangement of yellow and purple spots as the lateral mantle region.

The rhinophores arise on translucent stalks and have reddish-brown lamellate clubs, usually darker than that of the mantle, having fine white spots on the lamellae edges and a white apex. They are able to be retracted into pockets below the mantle for protection. The gill is spirally arranged around the anal papilla and can retract into a protective pocket below the mantle. The gill branches are translucent but carry dark (black or brown) lines up each of the four edges of the quadrangular form. White spots are evident on the outer faces in some specimens.

Distribution is wide in the Indo-West Pacific, from Japan down through Hong Kong, The Phillipines, Malaysia, Indonesia, PNG and Melanesia to central coasts of NSW and WA, Australia. It has even been recorded as far afield as the Red Sea.

Goniobranchus collingwoodi, as with all its Chromodorididae family members, is a spongivore. It, together with only a very small number of relatives, has been recorded feeding upon sponges of the Dictyodendrillidae family – Dictyodendrilla species including D. tenella.

The spawn of Goniobranchus collingwoodi is yellow and laid as an upright (on edge), slightly inwardly sloping spiral of from 2 to 3 whorls. Extra-capsular yoke has been observed in the spawn whereby it is associated with individual capsules and evenly distributed. Larvae are reported to be planktonic however, the exact development type is unrecorded.

The specific epithet of collingwoodi is in honour of Cuthbert Collingwood a 19th century surgeon and naturalist who collected and described specimens of nudibranchs during his voyages as ship’s surgeon.

Originally described as Chromodoris collingwoodi.

Rudman, 1987 & 2000, stated that Chromodoris collingwoodi has been confused with Chromodoris aureopurpurea Collingwood, 1881 (both now in Goniobranchus). This was the case in Thompson, 1972 and Willan & Coleman, 1984 but it should be mentioned that these were prior to the 1987 formal description of Chromodoris collingwoodi. Nevertheless, those authors chose to ignore or thought insignificant, among other features, the distinctive colouration to the central mantle in those specimens that eventually became C. collingwoodi as compared to that plainly shown for C. aureopurpurea in Collingwood’s 1881 illustration (see image gallery).

David A. Mullins – December, 2021

References:
– Collingwood, C. (1881). On some new species of nudibranchiate mollusca from the Eastern Seas.Transactions of the Linnean Society, London, Zoology, 2: 123-140, pls 9-10.

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

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

– 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.

– Rudman, W. B. (2000 May 21) Chromodoris collingwoodi Rudman, 1987. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/chrocoll and associated messages.

– Wells, F. E., & Bryce, W. (2000). Sea Slugs of Western Australia. Western Australian Museum.

– 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.

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

– 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)

– Yonow, N. (2018). Red Sea Opisthobranchia 5: new species and new records of chromodorids from the Red Sea (Heterobranchia, Nudibranchia, Chromodorididae). ZooKeys. 770: 9-42.

Other Sea Slugs in this Family (sighted)

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