Monticulus Cup-and-Saucer Shell, Crucibulum monticulus
Monticulus Cup-and-Saucer Shell. Shell collected off the beach of Punta Chivato, Baja California Sur, May 2025. Size: 2.5 cm (1.0 inch) x 0.5 cm (0.2 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.
Monticulus Cup-and-Saucer Shell, Crucibulum monticulus. Shell collected off the beach of Punta Chivato, Baja California Sur, May 2025. Size: 3.3 cm (1.3 inches) x 0.8 cm (0.3 inches). Collection, photographs and identification courtesy of Colin Campbell, DVM, Punta Chivato.
Phylogeny: The Monticulus Cup-and-Saucer Shell, Crucibulum monticulus (S.S. Berry, 1969), is a gastropod mollusk in the Calyptraeidae Family of Cup-and-Saucer Shells and Slipper Limpet Shells. The Crucibulum Genus is one of eleven genera in the Calyptraeidae Family, and there are nineteen species in the Crucibulum Genus. In Mexico they are known as Picacho. The name monticulus comes from the Latin word for little mountain.
Description: Monticulus Cup-and-Saucer Shells have an irregular ovate outline and a fairly high volcano-like profile. The shell shape can be impacted by the shape of the substrate on which they grow. This shell is sculpted with radial ribs that extend to the margin giving the the shell a scalloped edge. The apex is fairly centered, and slightly recurved. These shells may be white, brown or greenish-gray in color. White specimens usually have varying amounts of brown staining. The interior cup is white, flattened on the front side, and attached on the right side. Monticulus Cup-and-Saucer Shells reach a maximum of 6.0 cm (2.3 inches) in length, though most are about half that size.
Habitat and Distribution: Monticulus Cup-and-Saucers are found attached to rocks and other hard substrates. Some sources state that this is an intertidal species, though most hold that they are an offshore species found at depths between 35 m (115 feet) and 183 m (600 feet). Monticulus Cup-and-Saucer Shells are a subtropical to tropical Eastern Pacific species that are ENDEMIC to Mexican waters of the Pacific Ocean being found from Bahía de los Ángeles, Baja California in the Sea of Cortez, to the Gulf of Tehuantepec, Oaxaca. They have not been documented from the west coast of the Baja Peninsula.
Ecology and Behavior: Monticulus Cup-and-Saucers are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in the Calyptraeidae Family are either suspension feeders that feed primarily on plankton, which they capture with mucus nets created by their gills, or depositional feeders that eat detritus. They are gonochoric and reproduce sexually. Their engagement in any types of commensal, parasitic or symbiotic relationship has not been formally documented.
Conservation: the Monticulus Cup-and-Saucer has not been formally evaluated from a conservation perspective. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.
Synonym: None