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 Shell 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. They can be confused with the Pink-mouth Murex Shell, Hexaplex erythrostomus, which has solid pink lips.

Habitat and Distribution: Royal Murexes are found on sand and muddy sand substrates in the intertidal zone, and to depths up to 24 m (80 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 from north of Magdalena Bay, Baja California Sur, along the central and northwest coasts of the Baja Peninsula and north of Santa Rosalia, Baja California Sur, in the Sea of Cortez.

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.  Their engagement in any type of commensal, parasitic, or symbiotic relationship has not been formally documented. From a conservation perspective the Royal Murex has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern. The Royal Murex is edible and have been the target of commercial fisheries and shell collectors. Overharvesting has caused localized population declines.

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