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Recent human population growth in North America's southern Appalachian Mountains has raised concerns about the effects of ex-urban development on its streams and their at-risk biota. The few studies to examine effects of land-use change in this region found that many headwater species require well-forested watersheds. Alasmidonta raveneliana is endemic to montane streams in North Carolina and Tennessee and during the past 20 years populations have declined alarmingly in several former strongholds. In 2015, we conducted surveys for A. raveneliana and quantified in-stream habitat and land-use at 25 current or historically occupied sites in the Nolichucky Drainage. We found that A. raveneliana populations were only detected at sites with well-forested watersheds and low proportions of fine substrates. Thin-sections revealed that A. raveneliana is fast-growing and short-lived (max age ~ 12 years) which may be an adaptation to unpredictable headwater streams. However, like many headwater specialists, A. raveneliana appears sensitive to changes in forest cover. Our results suggest that subtle changes in stream habitats linked to land-use change are a significant threat to the long-term survival of this species. Protection of forested headwaters and restoration of riparian zones appear to be the best strategies for conserving populations of this critically endangered freshwater mussel. [ABSTRACT FROM AUTHOR]

Inaccurate taxonomy can lead to species in need of conservation being overlooked, which makes revisionary systematics crucially important for imperilled groups. The freshwater mussel genus Alasmidonta is one such group in need of study. Here, we take a multilocus phylogenetic approach to assess species-level taxonomy of Alasmidonta and test monophyly of this genus. Phylogenetic inference resulted in polyphyly of Alasmidonta. Lasmigona , which was included to test monophyly of Alasmidonta , was also polyphyletic. Species delimitation methods disagreed about whether Alasmidonta arcula , Alasmidonta triangulata and Alasmidonta undulata are distinct species, but all delimitation methods agreed that Alasmidonta harbours an undescribed species that would be considered Alasmidonta varicosa under current taxonomy. Given conflict among species delimitation methods and geographical separation, we maintain the current taxonomy for A. arcula and A. triangulata. The undescribed species is restricted to rivers of the Uwharrie Mountains region in North Carolina, USA that flow into the Pee Dee River from the east and can be distinguished morphologically from A. varciosa by higher and wider placed adductor mussels and a hooked pseudocardinal tooth. We offer insights into how supraspecific taxonomy of subtribe Alasmidontina might be resolved and formally describe the lineage from the Uwharrie Mountains region as Uwharrie elktoe, Alasmidonta uwharriensis sp. nov. [ABSTRACT FROM AUTHOR]

Terrestrial gastropods are among the most imperiled groups of organisms on Earth. Many species have a complex taxonomic history, often including poorly defined subspecies, most of which have not been the focus of modern systematics research. Genomic tools, geometric morphometrics, and environmental niche modeling were used to assess the taxonomic status of Patera clarkii nantahala (Clench & Banks, 1932), a subspecies of high conservation concern with a restricted range of approximately 3.3 km2 in North Carolina, USA. A genome-scale dataset was generated that included individuals with morphologies matching P. c. nantahala, P. c. clarkii, and one individual with an intermediate form between P. c. nantahala and P. c. clarkii that was initially hypothesized as a potential hybrid. Mitochondrial phylogenetics, nuclear species tree inference, and phylogenetic networks were used to assess relationships and gene flow. Differences in shell shape via geometric morphometrics and whether the environmental niches of the two subspecies were significantly different were also examined. Molecular analyses indicated an absence of gene flow among lineages of P. clarkii sensu lato. Analyses rejected our hypothesis that the intermediate shelled form represented a hybrid, but instead indicated that it was a distinct lineage. Environmental niche models indicated significant differences in environmental niche between P. c. clarkii and P. c. nantahala, and geometric morphometrics indicated that P. c. nantahala had a significantly different shell shape. Given multiple lines of evidence, species-level recognition of P. nantahala is warranted. [ABSTRACT FROM AUTHOR]