Molecular studies have recently led to the detection of many cryptic species complexes within morphologically ambiguous species formerly undescribed by the scientific community. Organisms such as land snails are at a particularly higher risk of species misidentification and misinterpretation, in that gastropod systematics are based almost entirely on external shell morphology. Subterranean ecosystems are associated with especially high degrees of cryptic speciation, largely owing to the abiotic similarities of these systems. In this study, we attempt to diagnose the potential cryptic diversity in the troglobitic land snail Helicodiscus barri. Land snails are generally associated with having low vagility, and as such this species' broad, mosaic distribution indicates the misdiagnosis of this organism as a single species. We analyze both mitochondrial (16S, CO1) and nuclear (28S, H3) genetic data for 23 populations. Phylogeny for H. barri was reconstructed using both maximum-likelihood and Bayesian approaches to assess relationships among populations, and two species delimitation methods (mPTP and ABGD) were used to detect the presence of unique molecular operational taxonomic units (MOTUs). Species delimitation results revealed seven and sixteen MOTUs respectively, suggesting the presence of several cryptic lineages within H. barri. To assess how external shell morphology corresponds with patterns of genetic and environmental variation, two morphometric approaches were used incorporating 115 shells from 31 populations. Both morphometric approaches reveal a significant environmental influence on shell morphology, and one approach showed the significance of MOTU groups. We discuss the delimitation and morphometric results and additionally provide discussion on the taxonomic and conservation implications of this study.A peer-reviewed open-access journal Nicholas S. Gladstone et al. / Subterranean Biology 30: 1-32 (2019) 2

A new species of cave snail (Littorinimorpha: Cochliopidae) in the genus Antrorbis is described from the dark zone of two caves in the Appalachian Valley and Ridge province in eastern Tennessee, United States. The Tennessee Cavesnail, Antrorbis tennesseensis Perez, Shoobs, Gladstone, & Niemiller, sp. nov. is distinguished from its only known congener, Antrorbis breweri, by the absence of raised tubercles on its finely spirally striate protoconch, and its unique radular formula. Moreover, A. tennesseensis is genetically distinct from A. breweri based on substantial divergence at the mitochondrial CO1 locus. This is the first cavesnail to be described from the Appalachian Valley and Ridge (AVR) physiographic province in the state of Tennessee, which previously represented a substantial gap in the distribution of stygobitic (i.e., aquatic, subterranean-obligate) gastropods.

The study of spring-and subterranean-associated microsnail species in the Appalachian karst region has focused disproportionately on the northern Appalachian Valley and Ridge (AVR), leaving many areas in the southern Appalachians unexplored. Consequently, biological inventories of subterranean habitats have been initiated in the southern AVR, particularly in the state of Tennessee. In 2013 and 2018, several previously unknown populations of a microsnail species were discovered from caves in eastern Tennessee. Through both morphological and molecular analysis, we identified these populations as the Blue Ridge Springsnail, Fontigens orolibas. These newly discovered populations represent a significant range extension of F. orolibas. As such, we reassess the conservation status of F. orolibas under NatureServe criteria and emphasize the need for further sampling efforts in the southern AVR for microsnails.

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