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Abstract

The Arkansas distributions of land mollusks of the family Polygyridae are presented based on the results of a state-wide survey and a critical review of published and unpublished locality records. Six of the 45 species previously recorded for Arkansas are excluded because they were misidentified, do not have established populations in the state, or are found only as fossils. Four others are not mapped because of a lack of recent distributional data or because the specific status of a form is unclear. There is a predominant pattern of occurrence limited to the northern, northwestern, or western parts of the state. The northwest has rock outcrops, including the limestone and dolomite outcrops of the Ozark Mountains, extensive broadleaf woodland cover, and has suffered less disturbance from agriculture than the southeast, which results in more suitable land mollusk habitats in the northwest. Secondary patterns are apparent for species that are of widespread or sporadic distribution throughout the state, or found only in the eastern part of the state. Compared to adjoining states, Arkansas has a high diversity of polygyrid snails, exceeded only by Tennessee (59 species) and Texas (40 species). The highest number of co-occurrences is between Arkansas and Missouri (94.1%) and Arkansas and Oklahoma (92.3%). Arkansas shares 36.9% of species with states that border the eastern side of the Mississippi River and 63.1% with states that border the western side of the river. These data illustrate the dominance of the Ozark/Boston Mountains fauna on Arkansas land snail distribution plus what could be regarded as a secondary mid-western element.

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