Thordisa albomacula Chan & Gosliner, 2006

There is a chance that the photos below represent different species. The main difference between the animals is the amount of white pigment on the body, including on the rhinophores and gills. Gosliner et al (2008) note that a distinctive feature is a linear patch of opaque white immediately anterior to the gills. Several, but not all, of the specimens below seem to have this patch. The notes on the living animal follow. The body is oval and flattened with a wide margin that hides the foot. It is basically soft, yet there is some firmness to the texture; it is not flaccid. There is a dorsal network of fairly low ridges, with the middorsal one from between the rhinophores to the gills most distinct. Ridges are decorated with irregular low pustules, often compound. About halfway to the margin from the middorsum, the ridges more or less break up into more irregular and rather dense pustules, larger in appearance than those on the ridges, although this may be due to the lack of ridges in this zone. Irregularly scattered over the dorsum are taller pustules, and a few of these have extending from them elongate simple tendrils about one-third to one-half the height of the rhinophores. Color is mostly orange brown with scattered dark brown patches visible under low magnification and relatively small and uniform sized red brown spots, sometimes densely speckled in the depressions between the ridges. Although varying between individuals, there are scattered white specks, concentrated on the tops of some of the pustules and more frequent toward the margin. The very edge of the margin may have numerous white specks and aggregations of specks. Underside of mantle is whitish with a brighter white network. The foot bottom is white, and the foot sides are white with light red brown patches. Oral tentacles are long and tentacular, white, and tipped with red brown. The rhinophore sheath is elevated, pustulose, and bears white pigment on pustules at its edge. Rhinophores are tall; peduncle and lower half of club are translucent gray with some of the ten lamellae very finely speckled or partially edged with purple brown or black. The flat-topped pustule-like tip is white. Gills are transparent, speckled irregularly with white and with a whitish irregular core. There are six tripinnate stalks set in a circle. About ten specimens have been found on lagoon reefs and pinnacles at Enewetak and Kwajalein, mostly under dead coral or sheets of aluminum siding storm debris. One was found at night in a small cave and two others in a patch of Halimeda algae. Depths ranged from 4 to 15 meters, and the sizes of two measured animals were both 12mm.

Specimens very similar to or perhaps the same species as the animal below are figured from New Caledonia on the Sea Slug Forum.

The specimen below was found at Kwajalein on the night of 30 August 2008 in a Kwajalein lagoon Halimeda patch.

The one in the two photos below was in a Kwajalein lagoon algae patch on 3 December 2012.

The next one was in a Halimeda algae patch on a Kwajalein lagoon reef on 13 October 2013.

This one from February 2016 had a lot more white and very distinct white dorsal papillae.

This one was under a rock on a lagoon reef just north of Bigej Island, Kwajalein Atoll, in about 6m of water.

Created 15 December 2006
Updated 23 March 2017

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