Opisthobranch of the Week Data
Limenandra nodosa originally appeared here on the Okinawa Slug Site as Baeolidia nodosa as I was, at the time, going along with Terry Gosliner's generic placement of the species (Gosliner, 1985). Michael Miller's recent review of the family (Miller, 2001) considers the genus Limenandra should be retained, and I'm currently going along with this view.
Limenandra nodosa is a small seldom encountered aeolid and is considered to be rare on Okinawa as I've collected only four individuals, although others have been seen but were neither photographed nor collected. The above featured animal was found during a high spring tide, crawling amid the interstices of a live stony coral reef near the edge of the reef drop-off. This and other collected specimens were noted to crawl with a decided "jerky" movement while slowing moving across a bit of coral rubble substrate. This circumtropical species is quite variable in appearance and there are a series of images posted on the Sea Slug Forum which illustrate some of this variation.
In as much as I currently don't have access to the original species description of L. nodosa by Haefelfinger & Stamm (1958), I've taken the following information from Rudman (1999) in the Sea Slug Forum:
This easily recognised aeolid has a circumtropical distribution. It was initially from the Mediterranean, and subsequently from the Caribbean, Gulf of California, and Hawaii. I have also found it in Tanzania, eastern Australia and New Caledonia. There is usually a pattern of concentric rings down the dorsal midline. In its most pronounced form they form a target-like patch of rings: yellow (outer), then red, then white (inner). The colours can be very faint or one or more can be absent. In some specimens only a whitish patch is present. The rings are found on the head, above the heart, and between each cluster of cerata. The cerata are arrange in double rows. Both the cerata and the rhinophores have white papillae. In specimens I have looked at in the Indo-West Pacific, there is a rhythmic simultaneous raising of the large inner cerata as the animal crawls along, making it appear to move in as series of jerks. This unique behaviour does not seem to have been noted from other parts of the world.