Sad Miter Shell, Strigatella tristis

Sad Miter Shell, Strigatella tristis.  Shell courtesy of the commercial fishermen of the greater Los Cabos Area, January 2010. Size: 2.5 cm (1.0 inch) x 1.1 cm (0.4 inches).

Phylogeny: The Sad Miter Shell, Strigatella tristis (Broderip, 1836), is a gastropod mollusk that is a member of the Mitridae Family of Miter Shells. The genus Strigatella is one of thirty-six genera in this family, and there are thirty-seven species in this genus. They are known in Mexico as Mitra Triste.

Description: The Sad Miter Shell is fusiform (spindle-shaped) with five or six slightly convex whorls. The body whorl is large and the spire is moderate in height. The shell is sculpted with low rounded axial ridges. The aperture is narrow and covers about one-half the shell length. The inner lip has 3 folds and the outer lip is thick and smooth. The exterior may be grayish-brown, olive brown, or dark brown in color. Most individuals have a white or light brown band along the top of each whorl. The interior is white to gray, sometimes with a brown wash. The Sad Miter Shells reach a maximum of 3.7 cm (1.5 inches) in length and 1.6 cm (0.6 inches) in height.

Habitat and Distribution: Sad Miter Shells are found on sand and mud substrates. They live in the intertidal zone and to depths of 25 m (80 feet). They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean including the Revillagigedo and Tres Marias islands, 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.

Ecology and Behavior:  Sad Miter Shells are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in this genus feed on sipunculid worms, tube worms, and mollusks.  They are gonochoric and reproduce sexually, with internal fertilization. Their engagement in any type of commensal, parasitic, or symbiotic relationship has not been formally documented. From a conservation perspective the Sad Miter has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms: Mitra (Strigatella) tristis, Mitra albofasciata, Mitra dolorosa, Mitra salinasensi, and Mitra tristis.