Phyllidiopsis monacha
(Yonow, 1986)

Order: NUDIBRANCHIA
Suborder: DORIDINA
Superfamily: EUDORIDOIDEA
Family: Phyllidiidae

DISTRIBUTION

Known only from the Red Sea

PHOTO

Locality: Eilat, Lighthouse Beach, 42m, Israel, Red Sea (Gulf of Eilat), 3 May 2006, coral reef. Length: 2cm. Photographer: Binyamin and Shulamit Koretz.

Phyllidia monacha Yonow, 1986 was described from a single preserved and decolourised specimen from the Red Sea [see message #19682]. Brunckhorst (1993) synonymized it with Phyllidiopsis dautzenbergi, presumably because the colour pattern of the preserved specimen [black pattern on whitish background] was very similar to the colour pattern of living P. dautzenbergi.

Binyamin & Shulamit Koretz's discovery of the animal figured here, suggest that Yonow's species is in fact distinctly different from P. dautzenbergi. The background colour is translucent white with a pattern of linked black patches down each side of the midline, each patch having Thin black streak running out to the mantle edge. Inside the black patches there is an irregularly shaped yellow median line. The rhinophores are yellow. The body and mantle are relativley flattened in shape and there appears to be no distinct median dorsal ridge. There are low rounded tubercles scattered over the mantle but rhinotubercles appear to be absent.

Although originally placed in the genus Phyllidia, Yonow gives no anatomical information to support that decision and it is not clear if Brunckhorst moved it to Phyllidopsis on anatomical grounds or simply because he considered a synonym of Phyllidiopsis dautzenbergi. The only character available from the photographs which can assist in generic placement is the absence of rhinotubercles, which are characteristic of Phyllidia and Fryeria. Yellow rhinophores, however, are characteristic of those two genera, but also occur in some species of Phyllidiopsis. Until specimens can be examined anatomically it is probably best to place this species in Phyllidiopsis.

This is a classic example of why it is best not to describe species from single, preserved, decolourised animals.

• Brunckhorst, D.J. (1993) The systematics and phylogeny of Phyllidiid Nudibranchs (Doridoidea). Records of the Australian Museum, Supplement 16: 1-107.
• Yonow, N. (1986) Red Sea Phyllidiidae (Mollusca: Nudibranchia) with descriptions of new species. Journal of Natural History 20 : 1401-1428.
• Yonow, N. (1988) Red Sea Opisthobranchia 1: The family Phyllidiidae (Mollusca, Nudibranchia). Fauna of Saudi Arabia 9: 138-151.

Authorship details
Rudman, W.B., 2007 (March 26) Phyllidiopsis monacha (Yonow, 1986). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/phylmona

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