Author: Hamatani, 1976

Order: Sacoglossa  Family: Caliphyllidae

Maximum Size: 15 mm

Sightings: Sunshine Coast

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Cyerce kikutarobabai Hamatani, 1976

Another of the outlandish decorated and delightful to observe species of the Cyerce genus. Dave Behrens (Behrens, 2001), has referred to it as being: “….almost psychedelic in appearance.”

Cyerce kikutarobabai is a ceras-bearing sacoglossan, a sap-sucking sea slug of the Caliphyllidae family. It is small, recorded to 15 mm in length, with a limaciform shape to the body proper. The oral tentacles are relatively long, being enrolled to form a tube. The rhinophores too, are long, being bifid (split into two) for the distal half, a family trait. Both parts of the distal half are grooved, the groove continuing through the proximal section. Distinct dark eye-spots are visible on the posterior face of the rhinophore bases, closely set just either side of the midline. The pericardial region bulges upwards as a prominence and with its white colouration appears like half an egg. Between the eyespots and pericardium, just offset to the right of the midline, is the raised anal papilla. The cerata are directly inserted without a stalk. They are elongated oval, leaf-like in shape and flattened, however both surfaces are inflated outwards giving a mostly smooth, cushion-like appearance. There are at least seven cerata in a row down each side of the body in a dorso-lateral position and they may vary in size. The cerata do not receive branches of the digestive gland. The foot is wider than the body, the anterior third being even wider still, with rounded corners and is separated from the rest of the foot by a transverse groove, this groove being a diagnostic trait for Cyerce. The tail end of the foot tapers quickly to a blunt point.

The body colour of Cyerce kikutarobabai is often described as translucent greyish-white however the specimens I have seen have a drab olive green colouration with green to white speckling. This is probably due to, as Rudman, 2001 suggests: “The body has a distinctive green tinge from the ingested algal food.” The oral tentacles are port-wine in colour as is an arrow-head shape (pointing posteriorly) behind the rhinophores with a streak between the eyes and then bifurcating anteriorly to reach the base of each rhinophore.The rest of the head region is white. The rhinophores are light brown with white to green patches. The anal papilla and pericardial hump are distinctively white. The cerata are translucent green with greenish white speckled spots. The distal half to third of the cerata have a dark purplish reticulation becoming solid with orange spots and an orange margin. Both faces of the cerata are similarly coloured. The foot is translucent with ventral speckling of iridescent green or white spots.

Distribution is Western Pacific Ocean, from Japan to Southern Queensland, including Philippines, Indonesia and New Caledonia.

There appears to be no consensus in the literature on the type of algae it feeds upon.

Named in honour of the Japanese malacologist Dr. Kikutaro Baba in celebration of his 70th birthday, who had been a teacher of this species’ author.

David A. Mullins – May 2021

References:

– Hamatani, I. (1976). A new species of Cyerce Bergh, 1871, C. kikutarobabai, from Yoron Island (Opisthobranchs: Sacoglossa). Publications of the Seto Marine Biological Laboratory, 23(3-5): 283-288.

– Rudman, W. B., (2001, April 23). Cyerce kikutarobabai Hamatani, 1976. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/cyerkiku

– Behrens, D., image by Miller, M. (2001). Opisthobranch of the Week, Week: 293. Mike Miller’s Slug Site. Available at: http://slugsite.us/bow/nudwk293.htm

– Coleman, N. (2008). Nudibranchs Encyclopedia. Neville Coleman’s Underwater Geographic Pty Ltd, Springwood, Qld. p. 66

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