Discordant Limpet Shell, Lottia discors

Discordant Limpet Shell, Lottia discors. Shell collected off the beach in the greater Los Cabos area, Baja California Sur, January 2020. Size: 4.1 cm (1.6 inches) x 3.8 cm (1.5 inches). Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

The Discordant Limpet, Lottia discors (Philippi, 1849), is a gastropod mollusk that is a member of the Lottiidae Family of True Limpets. They are also known as the Confusing Limpet and in Mexico as the caracol lapa. The shells have an oval profile and vary from low to high- arched. The exterior of the shell is sculpted with numerous fine radial ribs and the apex is fairly central and often eroded. The exterior of the shell is grayish to white and in some specimens the darker rays show through under the eroded apex; the interior is white with blue-gray, brown or greenish staining. Discordant Limpet Shells reach a maximum of 5.0 cm (2.0 inches) of length and 4.6 cm (1.8 inches) in height.

Discordant Limpets are found attached to rocks in the intertidal zone to depths up to 8 m (25 feet). They range from Magdalena Bay, Baja California Sur to the central coastline of mainland Mexico and the Revillagigedo Islands and Tres Marias Islands and are found only in the extreme southern portions of the Sea of Cortez.

Synonyms include Collisella discors and Patella aenigmatica.