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Family: Discidae
Common name: Black Mountain Disc
Discovery: Pilsbry, 1924
Identification
Width: 7.4 mm
Height: 2.4 mm tall
Whorls: 5+
The shell of Discus nigrimontanus looks flattened when seen from the side, with a low apex and a shallow, open umbilicus. The top of the whorls are bluntly angled, with the bottom even more blunt and sloping inward slightly. The shell is covered with coarse radial ribbing and it has a thin lip, as in most of its relatives. This species is similar in some ways to D. bryanti, though D. nigrimontanus’ whorls are not as sharply angled.
Ecology
Discus nigrimontanus is usually found in thin leaf litter in rocky upland woods (Hubricht, 1985).
Taxonomy
It has reportedly hybridized with D. patulus, giving rise to the form edentulus common in Arkansas (Hubricht, 1985). A synonym for this species is Gonyodiscus bryanti nigrimontanaus.
Distribution
This species has been reported in Alabama, Arkansas, Kentucky, Missouri, North Carolina, Tennessee, and Virginia. In Virginia it has been found only in the westernmost parts, in Grundy and Russell counties. This species is not reported for West Virginia by Dourson (2015), so specimen records from that state warrant scrutiny.
Conservation
NatureServe Global Rank: G4
NatureServe State Rank: Virginia, S1S3
Virginia’s wildlife action plan: Tier IV
