Wide-ribbed Cardita Shell, Cardites laticostatus
Wide-ribbed Cardita Shell, Cardites laticostatus. Shell collected off the beach at Punta Chivato, Baja California Sur, May 2025. Size: 3.6 cm (1.4 inches) x 2.6 cm (1.0 inch) x 1.2 cm (0.5 inches). Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.
Phylogeny: The Wide-ribbed Cardita Shell, Cardites laticostatus (G.B. Sowerby I, 1833), is a bivalve mollusk that is a member of the Carditidae Family of Little Heart Shells. The Cardites Genus is one of thirty-seven genera in the Carditidae Family, and there are thirteen species in the Cardites Genus. Note: some very good sources, such as World Register of Marine Species (WoRMS), hold that the valid species name is Cardites tricolor. Most other sources, such as the Global Biodiversity Information Facility (GBIF), indicate that Cardites laticostatus is the currently accepted name. We follow GBIF and thus recognize Cardites laticostatus for this species.
Description: The Wide-ribbed Cardita Shell has an ovate to trigonal outline and inflated in profile. These shells are of solid construction and are equivalve (both valves equal in size and shape). The anterior end is rounded. The posterior is longer and less widely-rounded to somewhat truncate (appearing chopped off). The exterior is sculpted with eighteen to twenty-two wide radial ribs, which terminate in a squared-off scalloping at the margin. There are commarginal striae between the ribs. The exterior of the shell is white with orange and brown blotches or wide bands. The interior is white. Shells in this genus have a minute anterior lateral tooth. The periostracum is adherent and dark brown. Wide-ribbed Cardita Shells reach a maximum of 6.0 cm (2.3 inches) in length.
Habitat and Distribution: Wide-ribbed Cardita Shells are found in rubble from the intertidal zone to depths up to 27 m (89 feet). They are a subtropical to tropical Eastern Pacific species. They are found in all Mexican waters of the Pacific Ocean with the exceptions that they are absent from north of Magdalena Bay, Baja California Sur, along the central and northwest coasts of the Baja Peninsula, and north of Bahía Kino, Sonora, in the Sea of Cortez.
Ecology and Behavior: Wide-ribbed Cardita Shells are suspension feeders that feed primarily on planktonic algae and suspended organic matter. They are gonochoric (male or female for life) and reproduce sexually, through broadcast spawning, with external fertilization. Their engagement in any type of commensal, parasitic, or symbiotic relationship has 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 considered to be of Least Concern.
Synonyms: Cardita arcella, Cardites laticosta, Cardites laticostata, Cardites reeveana, and Cardites tricolor.