Banded Periwinkle Shell, Littoraria variegata

Banded Periwinkle Shell, Littoraria variegata. Shell collected off the beach in the greater Los Cabos area, Baja California Sur. Size:  2.6 cm (1.0 inch) x 1.9 cm (0.7 inches).

Phylogeny: The Banded Periwinkle, Littoraria variegata (Souleyet, 1852), is a gastropod mollusk that is a member of the Littorinidae Family of Periwinkles. The genus Littoraria is one of seventeen genera in this family, and there are thirty-eight species in this genus. This species is also known as the Fasciate Periwinkle.

Description: The Banded Periwinkle shell has five or six whorls, with the body whorl being large.  They have a sharply pointed apex and their exterior is sculpted with fine lines running along the whorls. There are oblique growth ridges running the length of the shell. The exterior of the shell is cream to golden brown in color, with darker brown speckles, lines, and/or blotches; the interior is cream to yellowish. Some specimens have a solid or interrupted brown line along the margin of the outer lip of the aperture. Banded Periwinkles reach a maximum of 4.0 cm (1.6 inches) in length and 2.9 cm (1.2 inches) in height.

Habitat and Distribution: Banded Periwinkles are found attached to mangroves and on rocks in protected waters in the intertidal zone. They are a tropical Eastern Pacific species. In Mexican waters they range from Magdalena Bay, Baja California Sur to Guatemala. They are found throughout the Sea of Cortez, though limited by habitat.

Ecology and Behavior:  Banded Periwinkles are grazers that feed primarily on algae, fungi, diatoms, and mangrove leaf epidermis.  Their primary predators are crabs and shorebirds. They are gonochoric and reproduce sexually, with internal fertilization. The eggs are laid in protective capsules. This species is known to host endoparasitic trematodes. There is no mention in the available literature of them engaging in any types of  commensal or symbiotic relationships. 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: Littoraria (Littoraria) variegata, Littorina fasciata, and Littoraria  variegata.