Cuthona pustulata

(Alder & Hancock, 1854)

The slender, translucent white body measures up to 18 mm in length; the opaque white ovotestis and the brown jaws can usually be discerned through the skin. There are white patches on the skin of the rhinophores and oral tentacles, sometimes concentrated near the tips, and there are diagnostically important scattered white speckles on the cerata, contrasting with the light brown, pink or yellow hepatic contents. There are up to twelve rows of cerata, with up to eight cerata in each half-row.

It is associated with the hydroid Halecium muricatum .

British records have been few, most recently from Skomer and Lundy Islands in the south west, and from the island of Mull on the west coast of Scotland, down to 33 m. Elsewhere, it is known to occur in Iceland, the Kattegat and Brittany (Distr. C. pustulata).