Speckled Paper Cockle Shell, Papyridea aspersa

Speckled Paper Cockle Shell, Papyridea aspersa. Shell collected off the beach of Punta Chivato, Baja California Sur, March 2025. Size: 3.5 cm (1.4 inches) x 2.5 cm (1.0 inch) x 1.5 cm (0.6 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Speckled Paper Cockle Shell, Papyridea aspersa. Shell collected along the coast of Magdalena Bay, Baja California Sur, October 2019. Size: 4.4 cm (1.7 inches) x 3.5 cm (1.4 inches). Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

Phylogeny: The Speckled Paper Cockle, Papyridea aspersa (G.B. Sowerby I, 1833), is a bivalve mollusk of the Cardiidae Family of Cockles and True Cockle Shells. The genus Papyridea is one of forty-nine genera in this family, and there are eight species in this genus. They are also known as the Panama Paper Cockle Shell and in Mexico as Barberecho Jaspeado. This shell historically was considered to be a subspecies of either the Spiny Paper Cockle, Papyridae soleniformis or the Broad Paper Cockle, Papyridea lata, from the Western Atlantic.

Description: Speckled Paper Cockle Shells have an oval outline and a moderately inflated profile.  They are longer than they are high and the posterior end is longer than the anterior end. They are sculpted with 40 to 50 rounded radial ribs that extend beyond the posterior margin into a sharply serrated edge. They have small spines on the posterior ribs. The exterior of the shell is white to cream in color with light to dark reddish-brown speckles and blotches. The interior is shiny and white to light gray or bluish white in color, with red to maroon blotches. Speckled Paper Cockle Shells reach a maximum of 6.4 cm (2.5 inches) in length and 5.2 cm (2.0 inches) in height.

Habitat and Distribution: Speckled Paper Cockles are found on sand, from the intertidal zone to depths up to 160 m (525 feet). They are a subtropical to tropical Eastern Pacific species that are  found in all Mexican waters of the Pacific Ocean with the exception that they are absent from north of Cedros Island, Baja California, along the central and northwest coasts of the Baja Peninsula.

Ecology and Behavior: Speckled Paper Cockles are suspension feeders that feed primarily on plankton and other suspended organic matter. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. Their commensal, parasitic, or symbiotic relationships have not been formally documented. From a conservation perspective they have not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.

Synonyms:  Cardium aspersum and Papyridea bullata califoricum.