Description: This is one of the most common nudibranchs found on British shores and in many places it is known as the "sea-lemon". The mantle bears many short blunt tubercles. The mottled coloration of this nudibranch probably aids camouflage. The colours include yellow, brown, pink, green and white. There is also a bright red variety known as A. pseudoargus var. flammea. Some of the large individuals may grow to 120mm in length.

Habitat: Usually found on the low shore underneath large boulders. It feeds on the "bread-crumb" sponge Halichondria panicea and on other sponges such as Halichondria bowerbanki and Suberites ficus in the sublittoral. The spawn is a broad ribbon laid in a spiral attached by one edge.

Distribution: Common all around the British Isles and from Iceland to the Mediterranean.

Similar Species: The species most likely to be confused with Archidoris is Geitodoris planata which differs in having stellate spots on the dorsum and brown specks on the underside of the mantle.

Key Identification Features:

• Mottled pattern on mantle, colour variable.
• Mantle tubercles of two sizes.

Distribution Map from NBN: Doris pseudoargus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Doris pseudoargus at iNaturalist World Species Observations database.

WoRMS: Doris pseudoargus at World Register of Marine Species. Accepted name: Doris pseudoargus Rapp, 1827. AphiaID: 181228.

Classification: Biota; Animalia; Mollusca; Gastropoda; Heterobranchia; Euthyneura; Ringipleura; Nudipleura; Nudibranchia; Doridina; Doridoidei; Doridoidea; Dorididae; Doris