Phidiana anulifera
(Baba, 1949)

Order: NUDIBRANCHIA
Suborder: AEOLIDINA
Family: Glaucidae

DISTRIBUTION

Known from Japan & Hong Kong.

PHOTO

Hong Kong Workshop, April 1983, AM C139047
UPPER: Photo: Brian Darvell. LOWER: Head, showing orange-red markings and annulate rhinophores. Note left rhinophore missing. Photo: Bernard Picton.

Body translucent white with a close sacttering of opaque white specks. The oral tentacles have a broad reddish orange band near the base, and sometimes another near the tip. The region between these bands is opaque white, the tip teranslucent clear. The rhinophores have a about six, distinct and sharply edged annuli. Below the annuli the rhinophores stalk is translucent clear with scattered white specks. The annulate region is opaque white and the tip translucent clear. On the head there is a pair of thin orange-red lines which run from the inside base of the oral tentacles back to the rhinophores. A continuation of these lines runs around the back of the rhinophores and down to the first ceratal group on each side. This red-orange line reappears along the side of the body between each ceratal cluster. It also runs a short distance from the last ceratal cluster back on to the posterior foot. The cerata are translucent celar with white specks arranged in parallel lines along the cerata. The digestive gland gives the cerata a black appearance. Grows up to 10mm long.

It has similarities in colour and shape to Phidiana semidecora (Pease, 1860) from Hawaii and some authors have suggested they are the same species. This may be so but there are apparently consistent differences in colour. Although P. semidecora is reported to have orange markings on the head, they are never reported as a pair of lines as in P. anulifera and the Hawaiian species does not seem to have orange lines down the sides of the body between the ceratal clusters. There is also no report of rows of white specks on the cerata. At this stage I think we need to know a bit more about both species before we synonymise them.

References:
• Baba, K (1949) Opisthobranchia of Sagami Bay collected by His Majesty The Emperor of Japan. Iwanami Shoten, Tokyo. 194pp., 50 Pls
• Gosliner, T.M. (1979) The systematics of the Aeolidiacea (Nudibranchia: Mollusca) of the Hawaiian Islands, with descriptions of two new species. Pacific Science, 33(1): 37-77.

Authorship details
Rudman, W.B., 2001 (August 9) Phidiana anulifera (Baba, 1949). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/phidanul

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