Channelled Disc

(Pilsbry, 1924)

Discus clappi







Taxonomic Information

Gonydiscus clappi

Original Combination:

Named for American malacologist Dr. George H. Clapp


Original Description:

The shell is rather thin, flat above, broadly concave beneath, with carinae ar the periphery and base; cartridge buff. Inner whorls are simply convex, but the last three are convex, but the last three are convex with a concavity near the periphery; the last whorl is squarish in section, strongly concave between the peripheral and basal keels, and having a circular impression inside of the basal keel. Sculpture: most of the first whorl is smooth; then very fine, slightly protractive striae appear, and below the suture short, weak traces of readial riblets, which become longer, crossing the whorl, after the first 1 1/2 whorls. There are also very fine and weak traces of strongly retractive striae over the sculpture described, mainly near the periphery. On the neanic whorls the radial riblets become string, slighly curved, and retractive. On the last whorl these riblets are string, crenulating the two keels, becoming waek and reduced to mere striae between them, with some additional short striae in their intervals. In the concave base the riblets are moderately strong. The aperture is quadrate, or rather, stirrup-shaped, with the angles produced at the keels, a flat margin between them and opposite to that margin a concave parietal margin; upper and lower margins somewhat sigmoid. There is no internal thickening or callus. Height 2.3, diam. 7.4 mm.; 5 1/3 whorls. Northern Alabama: Jasper Point, a spur of the Cumberland Plateau, about 5 miles north to northeast of Gurley, Ala. "In dry forest among limestone rocks, under leaves and sometimes under stones. It was found in one place only though we searched in other parts of the same mountain." Collected by H.H. Smith, July 20, 1905. Type 91059 A.N.S.P. Part of the same lot in collections of G. H. Clapp and Bryant Walker. The characters of G. bryanti are exaggerated in this species, which is more highly evolved along the same lines. The basal concavity is wider, the basal keel more pinched out, and the concavity between the keel is deeper. The shape of the aperture differs. The habitat is remote from that of G. bryanti, no closely related form having been found between them. it has sculpture similar to that of bryanti on the last half whorl of the embryonic shell, but decidedly more stringly developed.

Original Description Citation:

Pilsbry, H. A. (1924). Some Alleghenian forms of the land-snail genus Gonyodiscus. Proceedings of the Academy of Natural Sciences of Philadelphia. 76: 417-421.
page(s): 417, figs. 2a, 3a

Ecological Information



Nature Serve Conservation Status:

G1: Critically Imperiled