Painted Snake Coiled Forest Snail
Painted Snake Coiled Forest Snail
|Listed||July 3, 1978|
|Family||Discidae (Forest Snails)|
|Description||Dome-shaped snail with six whorls and off-white brown blotches.|
|Reproduction||Young hatch as small adults.|
|Threats||Logging, grazing, quarrying.|
The painted snake coiled forest snail, Anguispira picta, is a dome-shaped snail with a sharp, smooth, keel-shaped ridge along the shell called a carina. Mature shells measure up to 0.8 in (2.1 cm) long and 0.4 in (1 cm) high. Shells have six whorls and indistinct ribbing, particularly on the body whorl. The adult shell is an opaque, off-white color with chocolate brown blotches on the upper surface. The lower surface has one row of large dark blotches and a second row of narrow, flame-like markings, extending into the hole at the base of the body whorl. Juvenile shells are translucent.
This snail is similar in appearance to Anguispira cumberlandiana found on the Cumberland Plateau.
Most land snails are hermaphrodites but self fertilization is rare. A courtship display generally initiates copulation and fertilization occurs internally, resulting in the production of jellylike eggs. The young hatch as small adults, their shells having fewer whorls than adults. The painted snake coiled forest snail is known to deposit clutches of small eggs with calcareous shells covered by thin membranes in the soil. Sexual maturity may come within a year after hatching. This species is not known to exhibit any parental care.
The painted snake coiled forest snail seems to have no daily periodicity even though other related species are known to be strongly diurnal. Most juveniles observed day or night were inactive and some adults were observed to forage day and night. It is likely that wet weather encourages activity while drought or cold decreases it. Individuals have been observed in the open during the height of summer and on warm days in November. They undoubtedly go under cover in the winter months.
The coiled forest snail has been found only on damp limestone outcrops, typically in crevices or under overhanging ledges. Slopes are very steep, often terminating in sheer cliffs that drop to the creek bed below. The habitat is thickly forested and has a profuse ground cover. The forest community is composed of American beech, sugar maple, shag-bark hickory, tulip poplar, white oak, and chinkapin oak. Ground cover is dominated by ironwood, dog-wood, witch hazel, sycamore, and many herbaceous plants, such as walking fern, alumroot, and wild ginger. The snail does not occur in adjacent tracts that have been heavily logged or clear-cut.
The historic range of this species is unknown, but it is probably endemic to the valleys and coves characteristic of the southwestern rim of the Cumberland Plateau in southern Tennessee west of Chattanooga.
The painted snake coiled forest snail is endangered by the restricted size of its range. Any substantial disturbance of the habitat could precipitate a sudden population decline. Logging, livestock grazing, and limestone quarrying are important sources of income to the residents of Franklin County. So far, the landowners of the cove have refused to sell timber or mineral rights to commercial interests and have cooperated with the Fish and Wildlife Service (FWS) to protect the habitat.
Conservation and Recovery
The FWS Recovery Plan for this species outlines a systematic research program that includes periodic monitoring of the population. Protection of the cove by land acquisition or by purchase of conservation easements is anticipated as funds become available. The Nature Conservancy and the Tennessee Wildlife Resources Agency have been active in securing the cooperation of local landowners.
U.S. Fish and Wildlife Service
Division of Endangered Species
1875 Century Blvd, Ste 200
Atlanta, Georgia 30345
Elwell, A. S., and M. Ulmer. 1971. "Notes on the Biology of Anguispira alternata. " Malacologia 11(1): 199-215.
Pilsbry, H. A. 1948. Land Mollusca of North America (North of Mexico). Academy of Natural Sciences, Philadelphia.
Smith, T. 1980. "Potential Preserve Site Summary."Report. The Nature Conservancy, Tennessee Field Office.
U.S. Fish and Wildlife Service. 1982. "Painted Snake Coiled Forest Snail Recovery Plan." U.S. Fish and Wildlife Service, Atlanta.