Caesia perpinguis

Lore & Background

The shell of Caesia perpinguis is ovate-acute, containing 5½ rounded and cancellated whorls. The longitudinal striae are nodulous except toward the base of the body whorl, and a deep sulcus lies behind the aperture. The outer lip is striated within, and the conical spire is longer than the aperture. The surface is roughened by a tubercle on the longitudinal at each intersection of the revolving lines.

A color form, described as Nassa perpinguis var. bifasciata, differs from the ordinary form by the presence of two broad spiral bands of deep chestnut color in abrupt contrast to the grayish-buff ground. One band sits just below the suture, one about the periphery, and occasionally a fainter band appears at the extreme base of the body whorl. The bands vary considerably in width, but no specimens having but a single band have been observed.

The species was recorded from Magdalena Bay on the western coast of Mexico and also from the Persian Gulf, indicating a disjunct distribution.

Reader's Guide

The significance of Caesia perpinguis lies in its documented color variation, which prompted the naming of a distinct variety, Nassa perpinguis var. bifasciata. This recognition reflects a historical approach to naming color forms within a species, even when the variation is limited to banding patterns. The species also contributes to understanding the biogeography of nassariid snails, as it occurs in both the eastern Pacific (Magdalena Bay, Mexico) and the Persian Gulf—a distribution that raises questions about dispersal or possible misidentification. The shell's cancellated sculpture and nodulous striae are characteristic features that aid in identification. Its inclusion in early malacological works by Marrat, Conrad, Melvill, and Adams underscores its place in the taxonomic literature of the 19th and early 20th centuries. The species remains a reference point for studies of color polymorphism and shell morphology within the Nassariidae.

Did You Know?

• The shell has 5½ whorls that are rounded and cancellated.
• A color form, var. bifasciata, has two broad chestnut bands on a grayish-buff ground.
• The species has been recorded from both Magdalena Bay, Mexico, and the Persian Gulf.
• The outer lip is striated within, and the spire is longer than the aperture.