Author: (Rudman, 1988)

Order: Nudibranchia  Family: Chromodorididae

Maximum Size: 180 mm

Sightings: Sunshine Coast

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Miamira moloch, (Rudman, 1988)

The molecular sequencing of the Chromodorididae family in 2012 removed some species from Ceratosoma and placed them in Miamira. Four of the described Ceratosoma species sequenced clustered separately from the other Ceratosoma species and were placed in Miamira genus. Whilst Ceratosoma moloch was not actually sequenced it is now a hypothesized member of Miamira.

The body of Miamira moloch is high, firm and elongate with a flat mantle that lacks any overhanging skirt apart from three lobes on each side that arise from the remnant lateral ridge. One pair is located each side of the head, another halfway between rhinophores and gill while the third, and largest pair, is just anterior to the gill. There is another lobe, situated just posterior to the gill, on the centreline, that curves up behind in the manner of a protective horn over the gill. This posterior arching lobe also marks the posterior termination of the mantle. All lobes carry tubercles at their terminations. There are also, scattered tubercles on the mantle and sides of the body but a much denser concentration on the tail. These tubercles vary in presentation between specimen types, some being compound and knobbly while others are pointed or “spikey”. While most species of Ceratosoma/Miamira have their defensive mantle glands concentrated in the protective horn over the gill Miamira moloch has also a heavy concentration in each of the lateral lobes and in fact the tip of every tubercle, regardless of location, has a defensive gland situated beneath.

There appears to be two main forms of Miamira moloch:

a) A form where the tubercles are compound and knobbly, the mantle is of a pink, purple or brown appearance (other colours are known) and mottled with lighter coloured “spots”. This colouration continues onto the aforementioned lobes. The actual tubercles however are white with closely concentrated spots of orange. This form has been sighted mostly around 140 mm in size but a 180 mm specimen has been recorded.

b) A form where the tubercles are pointed or “spikey”, the mantle is apricot in colour with white longitudinal lines or dashes with scattered purple dashes or spots. This colouration continues onto the lobes in a radial manner and even further onto the substantial “spikey” tubercles. This form has been sighted mainly around 80 mm in size.

Just to “muddy the waters” further, I have found a 30 mm specimen with “spikey” tubercles, a milky-white mantle background carrying purple longitudinal lines down the mantle, body and tail, and purple dashes and spots to the lobes and tubercles. #

Rudman, 2000 states: “…the tubercles thicken up and become quite rounded – a bit like encrusting coralline algae – when this species reaches about 120mm in length.” Coleman, 2008 also suggests that as the animal grows in size the spikey ends to the lobes  “….fuse into lumps.” This would infer that the smaller specimens with “spikey” tubercles grow into the larger specimens with knobbly tubercles and also take on a different mantle presentation. I have not seen any intermediate forms, so I am unable to confirm this view.

The tail is almost as long as the mantle. The rhinophores are lamellate and can contract into pockets beneath the mantle. The pockets possess raised rims. Rhinophore colour is most times the same colour as the base colour of the mantle often bearing white spots or spots of another colour that may be showing on the mantle. The gills too are similarly coloured as the mantle and often bearing spots of another colour on the mantle.

The spawn is reported as being bright red in colour but there are no reports of different colours from different forms. Miamira moloch feeds on sponges of the Dysideidae Family.

Although not a commonly encountered species Miamira moloch has a wide distribution in the Western Pacific from Japan down through Philippines, Thailand, Indonesia, PNG, Solomon Islands, Great Barrier Reef to the coast of NSW Australia.

The specific epithet of moloch is derived from Moloch horridus, the thorny dragon lizard of arid Australia, due to the resemblance.

Externally it is most similar to four species of Ceratosoma rather than Miamira, C. tenue, C. trilobatum, C. bicolor* and C. gracillium except that Miamira moloch bears tubercles on the lobes and body while the others are completely smooth. *[Rudman, 1988 synonymized C. bicolor with C. trilobatum although WoRMS, 2020 lists it as an “accepted” species.]

Originally described as Ceratosoma moloch.

# See NUDINOTE: Four and More into One; Variation in Miamira moloch

David A. Mullins – January 2021

References:

– Rudman, W. B. (1988) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: the genus Ceratosoma J.E. Gray. Zoological Journal of the Linnean Society, 93(2): 133-185.

– Rudman, W. B. (2000 December 29) Ceratosoma moloch Rudman, 1988. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/ceramolo and associated messages.

– Behrens, D., image by Strickland, M. (2000). Opisthobranch of the Week, Week: 237. Mike Miller’s Slug Site. Available at: http://slugsite.us/bow/nudwk237.htm

– Hermosillo, A. (2007). Opisthobranch of the Week, Week: 577. Mike Miller’s Slug Site. Available at: http://slugsite.us/bow2007/nudwk577.htm

– 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. p. 134

– 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).

– Behrens, D., image by Miller, M. (2017). Opisthobranch of the Week, Week: 997. Mike Miller’s Slug Site. Available at: http://slugsite.us/bow2007/nudwk997.htm

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

– MolluscaBase eds. (2020). MolluscaBase. Ceratosoma bicolor Baba, 1949. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=560055.