Jorunna rubescens Bergh, 1876 (Previously Kendrodoris rubescens)
This weeks BOW looks at a very strange looking dorid nudibranch which looks more like a Nembrotha or Polycera than a species of Jorunna. Until just recently (see Valdés & Gosliner, 2001), this species was assigned to the genus Kendrodoris. In this study Angel and Terry looked at the phylogenetic relationships of dorid genera in which the species bear caryophyllidia, that is spicules protruding from the notal papillae and tubercles. Based on the examination of the type species of all the described genera, they concluded that caryophyllidia-bearing dorids are a monophyletic group, and suggested generic synonymies amongst a number of caryophyllidia-bearing dorids. This work has important implications for nomenclature with some familiar names such as Kendrodoris disappearing. See the Sea Slug Forum for a list of these synonymies (just query synonymies in the search routine).
Jorunna rubescens has a strange body shape for a species belonging to the flat disk-shaped genera. It head is long and rounded like the front end of a B-52 bomber. The edge of the mantle seems to roll under hiding the hyponotum, and giving the appearance of a very thin foot. The gills emerge from a tall fluted swelling on the dorsum. It also has distinctive strange rhinophores. The clavus is a flat oval-shaped shaped structure, and the rhinophoral pocket has a raised collar. Color wise you can't really confuse it with any other species: the brown longitudinal lines are a giveaway. The amount of white and yellow found between these lines varies between specimens.
As seen in the Paul's photo here, the egg mass is a salmon pink color. The species occurs throughout the Indo-pacific and can get quite large reaching 20 cm in length.
Valdés, A. & Gosliner, T. M. 2001. Systematics and phylogeny of the caryophyllidia-bearing dorids (Mollusca, Nudibranchia), with the description of a new genus and four new species from Indo-Pacific deep waters.Zoological Journal of the Linnean Society, 133: 103-198.
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David W. Behrens
Pacific Coast Nudibranchs
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