Regal Tellin Shell, Eurytellina regia

Regal Tellin Shell, Eurytellina regia. Shell collected off the beach at Punta Chivato, Baja California Sur, April 2025. Size: 3.2 cm (1.3 inches) x 1.9 cm (0.7 inches) x 0.8 cm (0.3 inches)  Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Regal Tellin Shell, Eurytellina regia, Left Valve. Shell collected off the beach at Punta Chivato, Baja California Sur, April 2025. Size: 4.9 cm (1.9 inches) x 2.9 cm (1.2 inches) x 0.3 cm (0.1 inches)  Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Regal Tellin Shell, Eurytellina regia, Right Valve. Shell collected off the beach at Punta Chivato, Baja California Sur, April 2025. Size: 4.6 cm (1.8 inches) x 2.7 cm (1.1 inches) x 0.5 cm (0.2 inches)  Collection, photograph and Identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Phylogeny: The Regal Tellin Shell, Eurytellina regia (Hanley, 1844), is a member of the Tellinidae Family of Tellin Shells. The genus Eurytellina is one of one hundred four genera in this family, and there are eighteen species in this genus. In Mexico they are known as Tellina Regia. The taxonomy of this genus is currently being debated with some sources still consider this species to be within the genus Tellina, with the proper scientific name being Tellina (eurytellina) regis.

Description: Regal Tellin Shells have an elongate oval to trigonal outline, with a rounded anterior and a truncate posterior. The exterior is sculpted with wide commarginal ribs and fine commarginal striations. This sculpting may not be present on the posterior third of the shell. These pretty shells  may be reddish, light pink, or (rarely) white in color, usually with lighter concentric bands. Some specimens display lighter radiating bands as well. Regal Tellin Shells reach a maximum of 5.2 cm (2.0 inches) in length. They are distinguished from most other similar looking shells in the region by a raised strengthening rib on the interior, just posterior to the anterior adductor muscle scar. Though this trait is also shared by the Unevenly Striped Tellin Shell, Eurytellin inaequistriata, however, the Unevenly Striped Tellin is considerable shorter with a maximum length of 3.4 cm (1.3 inches).

Habitat and Distribution: Regal Tellins are found in sand and mud substrates  within the intertidal zone to depths up to 24 m (79 feet).  They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean with the exception that they are absent north of Laguna Ojo de Libre, Baja California Sur, along the central and northwest coasts of the Baja Peninsula.

Ecology and Behavior: Regal Tellins are suspension feeders that feed primarily on planktonic algae, and suspended detritus. They are gonochoric 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. These shells are generally considered to be rare. From a conservation perspective they have not been formally evaluated.

Synonyms: Tellina (Eurytellina) ecuadoriana, Tellina (Eurytellina) regia, Tellina ecuadoriana, and Tellina regia.