Speckled Paper Cockle Shell, Papyridea aspersa

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.

The Speckled Paper Cockle, Papyridea aspersa (G.B. Sowerby I, 1833), is a bivalve mollusk of the Cardiidae Family of Cockles and True Cockles, that have an oval profile and are longer than they are high and the posterior end is longer than the anterior end. They are moderately inflated and have 40 to 50 rounded radial ribs that extend beyond the posterior margin into a sharply serrated edge. They have small spines sculpting 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 shinny and white to light ray or bluish white in color, with red to maroon blotches. The Speckled Paper Cockle Shell reach a maximum of 6.4 cm (2.5 inches) in length and 5.2 cm (2.0 inches) in height.

The Speckled Paper Cockle is found over and within sand substrate at depths up to 160 m (525 feet). They are suspension feeders that filter plankton and fine detritus from the surrounding water. They are a resident of the Pacific and found in all waters with the exception that they are absent from Cedros Island, Baja California northward along the central and northwest coasts of Baja.

This shell historically was considered to be a subspecies of either Papyridae soleniformis or Papyridea lata from the Western Atlantic. Synonyms include Cardium aspersum and Papyridea bullata califoricum.