Phylogenetic analysis of threatened and range-restricted limestone specialists in the land snail genus Anguispira

摘要

Conservation laws often apply at the level of "species," yet species designations in many taxa were made using qualitative descriptions of a small number of morphological characters. This makes management of these groups challenging, especially when new taxonomically ambiguous populations are discovered. We used mtDNA sequence data (portions of 16S and cytb) to assess phylogenetic patterns within the limestone specialists in the land snail genus Anguispira, a group that includes highly range-restricted endemics and a newly discovered population of unclear affinities. Limestone mining is increasing in the Cumberland Plateau region (USA) where these snails live; the lack of phylogenetic information makes conservation management around these mines problematic. We found support for some aspects of traditional taxonomies: Anguispira picta, cumberlandiana, and alabama appear to be monophyletic groups, with the possible exception of one disjunct population of alabama. However, A. cumberlandiana columba appears to be more closely related to the widespread generalist A. alternata, a species than our data suggest is not monophyletic. In addition, the carinate shell (a highly flattened form with pinched edges, an adaptation to life in rock crevices) appears to have evolved just once in the genus. Last, both mtDNA data and quantification of shell morphology indicate that a newly discovered population appears to form a diagnosable monophyletic group. If corroborated by further analyses, this group may warrant elevation to the status of species.