Antonietta janthina
Baba & Hamatani, 1977

Order: NUDIBRANCHIA
Suborder: AEOLIDINA
Family: Glaucidae

DISTRIBUTION

Known only from SE Japan and a possible record from East Timor.

PHOTO

Upper: Shimoda, Izu Peninsula, Sagami Bay, Japan. ( Intertidal ), Pacific Ocean, 12 September 2003, under stone. Length: 6 mm. Photographer: Jun Imamoto. Lower: Osezaki, Izu Peninsula, Suruga bay, 3 m, Japan, Pacific Ocean, 30 April 2004, on the Hydractinia epiconcha. Length: 10 mm. Photographer: Jun Imamoto.

Brightly coloured aeolid with conspicuous yellow oral tentacles and a broad median band of the same colour running across the head and between the rhinophores. The smooth rhinophores are bright orange with a slightly lighter coloured band about midway down their length. The dorsal surface of the body, between the rhinophores is translucent with a heavy speckling of opaque white. The cerata appear purple with a white or yellow tip. This colour is produced by the purple colour of the digestive gland duct which fills each ceras and yellowish pigmentation on the apical skin of the cerata. There is also irrefular patching of opaque white on the ceratal wall but it only slightly obscures the purple of the digestive gland. The foot is translucent white and anteriorly is extended in to tentacular foot corners.

The cerata appear to be arranged in rows on each side of the body but Baba & Hamatani describe the post cardiac cerata as being arranged in single rowed arches. The arrangement of the cerata is the main reason they placed this species in Antonietta, but they were clearly hesitant in doing so. This species appears to feed exclusively on the hydroid Hydractinia epiconcha, which is often found growing on shells inhabited by hermit crabs.

• Baba, K. & Hamatani, I. (1977): A new species tentatively referred to Antonietta, Antonietta janthina, from Japan (Nudibranchia: Eolidoidea: Facelinidae). The Veliger 20(1): 9-13.

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