Speciosa Rock Shell, Vasula speciosa

Speciosa Rock Shell, Vasula speciosa. Shell collected off the beach of Punta Chivato, Baja California Sur, April 2024. Size: 1.6 cm (0.6 inches) x 1.4 cm (0.6 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.

Speciosa Rock Shell, Vasula speciosa. Shell collected off the beach at Punta Chivato, Baja California Sur, April 2022. Size: 3.6 cm (1.4 inches) x 3.3 cm (1.3 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato, Baja California Sur.

Speciosa Rock Shell, Vasula speciosa. Shell courtesy of the commercial fishermen of the greater Los Cabos area, Baja California Sur, April 2011. Size: 3.7 cm (1.5 inches) x 3.1 cm (1.2 inches).

Phylogeny: The Speciosa Rock Shell, Vasula speciosa (Valenciennes, 1832), is a gastropod mollusk that is a member of the Muricidae Family of Rock Shells. The genus Vasula is one of one hundred ninety-eight genera in this family, and there are three species in this genus. The name Vasula comes from Latin and means vessel or container. Speciosa means beautiful or showy.

Description: Speciosa Rock Shells are medium-sized, solidly-built, and comprised of 4 whorls. They have a diamond-shaped profile with broad shoulders that taper quickly to the base, and a low spire. They are sculpted with rows of short spiny ridges or knobs. Three of these knobs project at the outer lip of the aperture as spines, with the lower two being shorter than the upper one.  The exterior of the shell is white, with spiral bands of brown squares. The interior is white with many individuals having yellow inside the aperture.  Speciosa Rock Shells reach a maximum of 4.0 cm (1.6 inches) in length and 3.4 cm (1.3 inches) in height.

Habitat and Distribution: Speciosa Rocks are found clinging to rocks in the intertidal zone, and to depths up to 5 m (15 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 absent from north of Magdalena Bay, Baja California Sur, along the central and northwest coasts of the Baja Peninsula.

Ecology and Behavior: Speciosa Rocks are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in the Muricidae Family prey primarily on barnacles and mollusks. They are gonochoric and reproduce sexually. They are known to host the Shell-boring Barnacle, Cryptophialus wainwrightii, in what is believed to be a commensal relationship. 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: Purpura centiquadra, Purpura multilineata, Purpura speciosa, Purpura triserialis, and Thais (Thais) speciosa.