Heller & Thompson, 1983
Known only from the Red Sea
Eilat, Coral Beach Nature Reserve, Israel, Red Sea (Gulf of Eilat).
Depth: 16 m. Length: ca 1 cm. 10 December 2005 (night). coral reef. Photographer: Shulamit Koretz
Phanerophthalmus albocollaris Heller & Thompson,1983 was named from one 3 mm long specimen found on the Sudanese coast of the Red Sea. I had assumed it was probably a juvenile of P. smaragdinus, but the distinguishing feature they mention is a W-shape white mark on the posterior edge of the head shield, which is clearly visible in this photo. They describe the general colour as "yellowish brown, the central area being blackish. The posterior flaps of the headshield are coloured in a very conspicuous white, which forms the shape of a W.'
Unfortunately, the only anatomy they mention is the radular morphology, and in an animal so small it is not possible to make a valid comparison with the common P. smaragdinus, so I guess until we have evidence to the contrary we should consider Phanerophthalmus albocollaris to be a good species.
Heller, J. & Thompson, T.E. (1983) Opisthobranch molluscs of the Sudanese Red Sea. Zoological Journal of the Linnean Society, 78(4): 317-348.
Rudman, W.B., 2005 (December 17) Phanerophthalmus albocollaris Heller & Thompson, 1983. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/phanalbo