Anguispira knoxensis, also known as the rustic tigersnail or rustic disk, is a rare species of pulmonate land snail in the family Discidae (the disk snails). It was originally described by Henry Augustus Pilsbry in 1901 as a variety of Anguispira alternata under the name Pyramidula alternata var. knoxensis.
Taxonomy The species belongs to the genus Anguispira within the family Discidae. Its original name was Pyramidula alternata var. knoxensis (Pilsbry, 1901), and it was later elevated to full species status. The currently accepted binomial name is Anguispira knoxensis (Pilsbry, 1901).
Appearance The rustic tigersnail has a larger, more robust shell than Anguispira alternata, marked by small, fine riblets. The entire shell is covered with a secondary structure of fine wrinkles that are almost invisible to the naked eye but give the shell a dull appearance compared to other Anguispira species. The shell is described as rusty brown in color with inconspicuous flame-like markings, and it ranges from 23 to 25 mm in diameter.
Distribution and Habitat The species is endemic to the Great Smoky Mountains in southeastern Tennessee. It can currently be found in three Tennessee counties: Monroe, Blount, and Knox Counties. A population was historically recorded around Hazel Creek in North Carolina, but the species is now considered likely extirpated from that state. The snail inhabits areas near large, rotting hardwood logs in advanced stages of decay, in leaf mold, or in soil, and is typically found near limestone outcrops.
Conservation Status Due to its limited range and the difficulty of locating new populations, Anguispira knoxensis is listed as critically imperiled in Tennessee by NatureServe.
