Gnidia Venus Clam Shell, Chionopsis gnidia

Gnidia Venus Clam Shell, Chionopsis gnidia. Shell collected in the Puerto Adolfo Lopez Mateos, Baja California Sur, March 2019. Size: 5.8 cm (2.3 inches) x 5.0 cm (2.0 inches).  Identification courtesy of Bob Hillis, Ivins, Utah.

Gnidia Venus Clam Shell, Chionopsis gnidia. Shell collected off the beach at Punta Chivato, Baja California Sur, December 2021. Size: 5.8 cm (2.3 inches) x 5.0 cm (2.0 inches). Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Phylogeny: The Gnidia Venus Clam, Chionopsis gnidia (Broderip and G. B. Sowerby I, 1829), is a bivalve mollusk that is a member of the Veneridae Family of Venus Clam Shells. The genus Chionopsis is one of one hundred seven genera in this family, and there are nine species in this genus. They are known in Mexico as Venus Vistosa.

Description:  The Gnidia Venus Clam Shell has a subtrigonal-ovate profile, is fairly thick and somewhat inflated. It has a notch under the prominent beak. The exterior of the shell is sculpted with high, thin concentric ribs that have scalloped edges. They also have numerous, much finer, radial ribs across the surface. The exterior of the shell ranges from white to tan; the interior is white. Gnidia Venus Clams reach a maximum of 12.0 cm (4.7 inches) in length and 10.3 cm (4.1 inches) in height.

Habitat and Distribution:  Gnidia Venus Clams are found within sand and mud substrates from the intertidal zone to depths up to 36 m (110 feet). They are a subtropical to tropical Eastern Pacific species that in Mexican waters range from Cedros Island, Baja California south to Guatemala. They are found throughout the Gulf of California.

Ecology and Behavior: Gnidia Venus Clams are infaunal suspension feeders that feed primarily on planktonic algae and suspended organic matter. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. There is no mention in the available literature of them engaging in any types of parasitic, 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:  Chione gnidia, Chione manabia and Venus gnidia.