Aspera Periwinkle Shell, Echinolittorina aspera

Aspera Periwinkle Shell, Echinolittorina aspera. Shell collected off the beach in the greater Los Cabos area, Baja California Sur, December 2018. Size: 1.0 cm (0.4 inches) x 0.7 cm (0.3 inches).

The Aspera Periwinkle, Echinolittorina aspera (Phillipi, 1846), is a gastropod mollusk that is a member of the Littorinidae Family of Periwinkles. The name “Aspera” comes from the Latin word for rough or uneven that refers to the surface texture, shell outline, or color variations. The shell has five to six whorls with the anterior whorl being large, giving the shell a squatty appearance, with a sharply pointed apex. The shells are highly variable in external sculpting and coloration; some have a series of fine ridges following along each whorl while others have fine radiating lines. The exterior of the shell is light brown to white in color, with brown or grayish markings that appear as radiating straight or wavy lines, zig zags, revolving lines that look like a series of dashes, or diagonal lines. Some specimens have bluish spots; most individuals have at least some chocolate brown around the aperture. The Aspera Periwinkle Shells reach a maximum of 2.0 cm (0.8 inches) and 1.4 cm (0.6 inches) in height.

Aspera Periwinkles are found, often in clusters of many dozens of individuals, attached to shoreline rocks, in the mid to high intertidal zone. They range from Guerrero Negro, Baja California to Ecuador, including the Galapagos Islands. This species is found throughout the Sea of Cortez.

Synonyms include Littorina aspera and Nodilittorina aspera.