Black Mountain Disc
Gonydiscus bryanti nigrimontanus
Spire somewhat convex; peripheral angle blunt, the basal angle very blunt in the first part of the whorl, entirely rounded off in the last half; space between the periphery and base flat or very slighlty concave in the first half of the last whorl, and convex in the latter part, the riblets continued as straie across it. Microscopic criss-cross sculptureof the embryonic shell is very much weaker than in G. bryanti, but of the same character, though almost effaced. Aperture very shortly ovate. slightly angular at the perifery; the lip well thickened a short distance within, but there is no columellar tubercle; umbilicus as in G. bryanti. Height 2.4 , diam. 7.4 mm.; 5 1/4 whorls. North Carolina: Potato Top, Black Mountains, type locality: Bee Tree Cove, on the western side of Big Craggy Mountain in the same range. Collected by Bryant Walker and J.H. Ferriss. Type 84035 ANSP; others of the same lot in collections of Walker and Ferriss. The remblance to G. bryanti is more marked in the young than in the mature specimens, in which the last whorl is far less stroongly angular. In the characters differentiaiting this form from G. bryanti it approaches G. perspectivus (Say); but the small caliber of the whorls, their angulation, and the very broad excavation of the base, are characterisitics of g. bryanti, and unlike G. perpectivus.
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): 419, figs. 2c, 3c
Nature Serve Conservation Status:
G4: Apparently Secure