Polycera quadrilineata

Polycera quadrilineata, is a sea slug, a species of dorid nudibranch. It is a marine gastropod mollusc in the family Polyceridae. The specific epithet quadrilineata means four-lined and refers to the four longitudinal black lines present on the original specimen. This species is sometimes called the fourline nudibranch. In 2020 a integrative molecular and morphological study showed that P. quadrilineata was a complex of two species in the NE Atlantic and one of these species was given the new name Polycera norvegica.