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1 September 2014 Overview of the North American Terrestrial Gastropod Fauna
Jeffrey C. Nekola
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A revised database of terrestrial gastropods from North America north of Mexico was assembled in the spring of 2012, which included not only all likely species-level entities, updated family and naturalized exotic assignments, but also shell and body size data. Analyses of these reveal that: (1) the fauna represents approximately 1,200 species, and is dominated by the Polygyridae, Helminthoglyptidae, and Vertiginidae. This number is surprisingly small, with other land masses of ½ to 1/100th the size possessing a larger fauna; (2) naturalized species make up 6% of the total fauna; (3) while slugs represent only 7% of the native fauna, they constitute over 1/3 of the naturalized fauna; (4) the accumulation curve for recognized species is sigmoidal, with current rates being the lowest experienced in 200 years. As a result, it appears that only 150–300 net additional taxa may await description, with the principle future taxonomic activity being revisionary work; (5) like other faunas, both native and naturalized land snails in North America possess bimodal height/width ratios; (6) native land snails possess a bimodal, right-skewed biovolume distribution along a log axis, which differs greatly from the unimodal left-skewed distribution typical of many other taxa groups; and, (7) the distribution of species within families and genera, and of the number of species described by a given researcher all possess Power Law/Log Normal distributions characteristic of complex adaptive systems.

Jeffrey C. Nekola "Overview of the North American Terrestrial Gastropod Fauna," American Malacological Bulletin 32(2), 225-235, (1 September 2014).
Received: 14 January 2013; Accepted: 1 August 2013; Published: 1 September 2014

Body size patterns
complex systems
land snail
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