Royal Murex Shell, Phyllonotus regius

Royal Murex Shell, Phyllonotus regius. Shell provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, April 2010. Size: 14.1 cm (5.6 cm) x 9.8 cm (3.9 inches).

Phylogeny: The Royal Murex Shell, Phyllonotus regius (Swainson, 1821), is a gastropod mollusk that is a member of the Muricidae Family of Rock Shells. The genus Phyllonotus is one of one hundred ninety-eight genera in this family, and there are thirteen species in this genus. They are also known as the Regal Murex and in Mexico as Busano Real and Caracol Real.

Description: Royal Murex Shells are sturdy, globose in shape and have a fairly low spire. The body whorl is sculpted with six to eight varices, made of double rows of scaly spines. The siphon canal is wide and closed. They have a large aperture, which has wide, brown to almost black, lips. The exterior of the shell is white, but some specimens have pink and brown showing though. Royal Murex Shells reach a maximum of 18.0 cm (7.1 inches) in length and 12.5 cm (4.9 inches) in height. Royal Murex shells can be confused with the Pink-mouth Murex Shell, Hexaplex erythrostomus , which has solid pink lips.

Habitat and Distribution: Royal Murex Shells are found on sand and muddy sand substrates. They live in the intertidal zone, and to depths up to 24 m (80 feet). They are a subtropical to tropical Eastern Pacific species. In Mexican waters they range from Magdalena Bay, Baja California Sur, to Guatemala. They are found in the Gulf of California as far north as Santa Rosalia, Baja California Sur.

Ecology and Behavior: Royal Murex Shells are predators that feed primarily on bivalves. They are preyed upon by crabs, fish, and sea stars.  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. They are edible and have been the target of commercial fisheries and shell collectors. Overharvesting has caused localized population declines. From a conservation perspective they have not been formally evaluated.

Synonyms: Chicoreus (Phyllonotus) regius,  Chicoreus regius, Hexaplex (Muricanthus) regius, Hexaplex regius, Murex regius, and Murex tricolor.