Thorunna montrouzieri Rudman, 1995

When we found the first two specimens of this species on 24 December 2007, we thought it was quite similar to Thorunna montrouzieri from New Caledonia, except in that species, the wide orange marginal band is interrupted twice in the front and once in the rear by patches of purple not present in the Marshall Islands specimens. A pair of these was found, the larger measuring 11mm in length, and neither had any trace of the anterior or posterior purple except for a light tinge of the color at the tip of the tail. The two nudibranchs were under a chunk of dead coral resting on a rubble bottom on a Kwajalein Atoll lagoon pinnacle at a depth of about 8m. The two nudibranchs were eating a thinly encrusting light tan colored sponge, and there was a white egg mass nearby. Since it appeared that this could be something different, one specimen was collected for closer examination; the other crawled into a hole in the rock out of reach. The first three shots show one of the specimens found at that time.

On 20 January 2008, we returned to the same site and under the very same rock were again two specimens, at least one of them different from the previous observation. Notice from the photos below that the smaller one, which measured 9mm in length, has purple patches replacing the orange marginal coloration just forward of the rhinophores. Although even this one lacks a similar purple patch posteriorly, we now have less hesitation about identifying this species as T. montrouzieri. These two were munching on the same encrusting sponge colony as last time, and there was a new egg mass, seen at the left side in the bottom photograph.

Created 25 December 2007
Updated 4 February 2008