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The plicate rocksnail, scientific name ''Leptoxis plicata'', is a species of freshwater snail with a gill and an operculum, an aquatic gastropod mollusk in the family Pleuroceridae. This species is endemic to the United States, specifically the state of Alabama. The snail has been listed as endangered on the United States Fish and Wildlife Service list of endangered species since October 28, 1998.〔Fish and Wildlife Service. (October 28) 1998. (''Endangered and Threatened Wildlife and Plants; Endangered Status for Three Aquatic Snails, and Threatened Status for Three Aquatic Snails in the Mobile River Basin of Alabama'' ). Federal Register, Vol. 63, No. 208, Rules and Regulations, Accessed 26 January 2009.〕 == Description == The plicate rocksnail is a pleurocerid snail with a shell that grows to about 20 mm (0.8 in) in length. Shells are subglobose with broadly rounded apertures. The body whorl may be ornamented with strong folds or plicae. Shell color is usually brown, occasionally green, and often with four equidistant color bands. The columella (central column or axis) is smooth, rounded, and typically pigmented in the upper half. The aperture is usually bluish-white, occasionally pink or white.〔 The operculum (plate that closes the shell when the snail is retracted) is dark red, and moderately thick.〔〔Goodrich C. 1922. ''The Anculosae of the Alabama River Drainage''. Miscellaneous Publications, Museum of Zoology, University of Michigan (7):1-57.〕 Although morphologically similar to the basin's other three surviving rocksnail species, the plicate rocksnail is genetically distinct.〔〔Lydeard C., W.E. Holznagel, J. Garner, P. Hartfield & J. M. Pierson. 1997. ''A molecular phylogeny of Mobile River drainage basin pleurocerid snails (Caenogastropoda: Cerithioidea)''. Molecular Phylogenetics and Evolution 7(1):117-128.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Plicate rocksnail」の詳細全文を読む スポンサード リンク
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