Verification of the Specific Status of the Endangered Anthony's River Snail, Athearnia anthonyi, Using Allozyme Electrophoresis

Although nominally the single surviving representative of a unique pleurocerid taxon, Athearnia anthonyi (Budd, in Redfield, 1854) is so rarely collected that even its specific status has been uncertain. We used allozyme electrophoresis to compare a population of A. anthonyi to the similar pleurocerid snail, Leptoxis praerosa (Say, 1821), co-occurring with it in the Sequatchie River of Tennessee, and to a second population of L. praerosa collected approximately 500 km distant. Observed levels of heterozygosity offered no evidence of inbreeding or unusually severe population bottlenecking in any of these populations. Strikingly different allele frequencies at five of the eleven enzyme loci examined, together with differences in shell morphology especially apparent in young individuals, confirmed that A. anthonyi and L. praerosa are distinct species. Their similarity at the six loci remaining supports previous suggestions that Athearnia may be a subgenus of Leptoxis.