Mediterranean, [Records from Caribbean and Japan need confirmation].
Antalya, Turkey, May 2002., Depth: 15m, Size: approx 4cm. Photo: Baki Yokes.
Notarchus is a genus of Sea Hare in which the parapodia are almost completely fused. There is a small anterior opening to allow an exchange of water to the mantle cavity. They have no shell. They are able to escape from danger by swimming by jet propulsion. A most spectacular if inelegant display which I have described in a message below.
There are two described species, Notarchus punctatus with an armed penis and Notarchus indicus without. N. punctatus is recorded from the Mediterranean. Baba, (1938) describes a subspecies N. indicus armatus from Japan, and subsequently Marcus (1962) removes it to the species N. punctatus, and identifies Caribbean animals as N. punctatus armatus. Notarchus indicus is known from much of the Indo-West Pacific under various names. Clearly the Caribbean and Japanese records need to be clarified and the subspecies armatus re-evaluated.
• Philippi, R.A. (1836) Enumeratio molluscorum siciliae. Berlin.
Rudman, W.B., 2002 (June 11) Notarchus punctatus Philippi, 1836. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/notapunc