Clanculus robertsi
A marine gastropod mollusk in the family Trochidae.
Clanculus robertsi is a marine gastropod mollusk belonging to the family Trochidae, commonly known as top snails. The shell reaches a height of 12.5 mm and a diameter of 13 mm. In color and surface texture, it closely resembles *Clanculus clanguloides*, but it stands apart due to its taller, more turban-like shape and more pronounced teeth. It also shares features with *Clanculus stigmatarius*, though the coloration is entirely different.
The shell has an elevated conical spire, with the tip tinged orange. The upper whorls are nearly flat and separated by a fine suture that becomes deeper on the body whorl. The body whorl is slightly convex, rounded at the edge, and bends downward and flattens near the opening. The base is fairly flat, similar to that of *C. clanguloides*. The surface is covered with spiral rows of closely packed rounded granules; these rows are slightly spaced on the upper part and closer together underneath. On the body whorl, there are 17 or 18 such rows, with the seventh sitting at the periphery—just as in *C. clanguloides*. The gaps between the spiral ridges are marked by fine oblique and spiral striae, which can be hard to see and sometimes give the surface a granular look under magnification.
The aperture is nearly horizontal and four-sided. The upper lip is straight, with a large, squarish, nearly split tubercle in the middle. Inside, a lamellar fold marks the position of the periphery. The curved basal margin is slightly expanded and bears two or three fold-like denticles, with the edge itself finely toothed. The oblique columella enters the narrow umbilicus deeply and attaches at the center of the shell’s axis; it has a slight tooth above, a narrow tooth below the middle, and ends in a large, heavy tooth that is double or triple. The parietal area is covered by a white callus with many wrinkles, one or two of which extend into the aperture. The umbilicus is ringed by a callus with strong radiating folds. The overall coloration matches that of *C. clanguloides*. In older specimens, the compression and bending of the body whorl gives the shell a bullet-like shape.
This species is found in the Red Sea.
Quick Facts
- Taxon
- Clanculus robertsi
Facts from the source article.
Lore & Background
The shell of Clanculus robertsi attains a height of 12.5 mm and a diameter of 13 mm. Its spire is elevated conical, with the apex tinged with orange. The upper whorls are nearly flat, separated by a linear suture that becomes more deeply impressed at the body whorl. The body whorl is slightly convex, rounded at the periphery, deeply deflected and flattened toward the aperture. The base of the shell is rather flattened. The sculpture consists of spiral series of closely set rounded granules, numbering 17 or 18 upon the body whorl, with the 7th series upon the periphery. The interstices between lirae are finely obliquely and spirally striate, sometimes giving a granulate appearance under a lens. The aperture is nearly horizontal and tetragonal, with a straightened superior lip bearing a very large subbifid squarish tubercle in the middle. The basal margin is curved, slightly expanded, with two or three fold-like denticles inside. The oblique columella deeply enters the narrow umbilicus and is inserted in the center of the axis, bearing a narrow tooth below the middle and terminating in a large, heavy bi- or triplicate tooth. The parietal area is covered by a white callus with numerous wrinkles. The umbilicus is surrounded by a radiately strongly plicate callus. The coloration is the same as in Clanculus clanguloides. On old specimens, the compression and deflection of the body whorl gives the shell a bullet shape.
Reader's Guide
Clanculus robertsi is significant as a species within the Trochidae family, distinguished from similar species like Clanculus clanguloides by its greater altitude, more turbinate form, and greater development of the teeth. It also resembles Clanculus stigmatarius in these characters but differs in coloration. The species is described from specimens found in the Red Sea. Its detailed shell morphology, including the number of spiral granule series and the structure of the aperture and columella, provides taxonomic clarity within the genus. The bullet shape of old specimens is a notable ontogenetic change. The species is documented in the ANSP Malacology Collection, contributing to the understanding of trochid diversity in the Red Sea region.
Did You Know?
- The shell height of Clanculus robertsi attains 12.5 mm and its diameter 13 mm.
- The body whorl bears 17 or 18 spiral series of closely set rounded granules.
- This marine species occurs in the Red Sea.
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