Antarctic waters - circumpolar, and Antarctic Peninsula and nearby islands [South Shetlands, South Orkneys].
Locality: Cuverville Island, Antarctic Peninsula, Southern Ocean. 18 meters. Length: 30 mm. 8 February 2007. Rock wall. Photo: David Cothran
Antarctic nudibranchs of the Family Charcotiidae [Charcotia, Pseudotritonia] are difficult to identify just from photos, because most of them have been defined by their internal anatomy [see message #19509]. The notum (or mantle) is wider than the foot, and along each side it has a number of waves or folds. There is an oral veil and the anus opens about halfway back on the right side of the body. In Pseudotritonia, the digestive gland has branches which extend out to the dorsal surface of the mantle, the mantle edge, the sides of the body, and the foot. Two species, Pseudotritonia quadrangularis and P. antarctica, are reported to have some papillae at the mantle edge, but these apparently disappear in preserved specimens. Of these two species, P. quadrangularis is reported to have 'petal-shaped' rhinophores, while the other is said to digitiform rhinophores. It grows to about 30 mm in length.
It has twice been found on bryozoan colonies but nothing definite is known about its biology.
Wägele, H. (1991) The distribution of some endemic Antarctic nudibranchia. Journal of Molluscan Studies 57: 337-345.
Wägele, H. (1991) Studies on the morphology and anatomy of the Antarctic nudibranch genera Pseudotritonia Thiele, 1912 and Telarma Odhner, 1934 with a discussion of the family Charcotiidae Odhner, 1926 (Nudibranchia: Opisthobranchia). Zoological Journal of the Linnean Society 101: 359-389.
Wägele, H., Bullough, L. W., and Barnes, D. K. A. (1995) Anatomy of Pseudotritonia Thiele, 1912 and Notaeolidia Eliot, 1905 (Gastropoda: Opisthobranchia: Nudibranchia) from Signy Island, Antarctica. Journal of Molluscan Studies 61: 209-213.
Rudman, W.B., 2007 (February 21) Pseudotritonia quadrangularis Thiele, 1912. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/pseuquad