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The Edwards and Edwards-Trinity Aquifers of Texas have diverse stygofauna, including fifteen species of snails found in phreatic and hyporheic habitats. These species have the hallmarks of adaptation to subterranean environments including extremely small body size and the loss of pigmentation and eyes. Here we use an integrative taxonomic approach, using shell, radula, and anatomical features as well as mitochondrial and nuclear DNA data, to circumscribe a new genus and two new cavesnail species from Central Texas. Vitropyrgus lillianae gen. et sp. nov. is described from Comal Springs (Comal County) and Fessenden Springs (Kerr County) and distinguished by a glassy, highly sculptured shell and distinctively simple, unornamented penial morphology. We also describe Phreatodrobia bulla sp. nov. from Hidden Springs (Bell County), and several other springs in Bell & Williamson Counties, Texas. This species has a smooth, unsculptured teleoconch, a reflected and flared lip, and deeply concave operculum. [ABSTRACT FROM AUTHOR]

The Chihuahuan Desert swamps are a hotspot for imperiled organisms including freshwater springsnails and bacteria. Many of these taxa are endemic to the desert and to the individual waterbodies where they occur. Efforts to conserve diversity in these threatened areas must account for the life history of the organisms, but also interactions between organisms including microbes. We documented the microbial assemblage associated with Tryonia metcalfi, a critically imperiled freshwater snail endemic to a ciénega system in western Texas. We identified 14 bacterial families in our snail samples and determined a core assemblage of 19 bacterial taxa (4 of which represented novel lineages) that are likely dependent on the snail. Future conservation efforts involving T. metcalfi and its environment should therefore consider the microbial diversity associated with both the snail and the ciénegas. En las ciénegas del desierto de Chihuahua habitan muchos organismos en peligro, entre ellos caracoles de agua dulce y bacterias. Muchos de estos taxones son endémicos del desierto y de los específicos cuerpos de agua donde ocurren. Esfuerzos para conservar la diversidad en estas áreas amenazadas deben tomar en cuenta la historia de vida de los organismos junto con las interacciones entre ellos, incluyendo microbios. Documentamos el conjunto microbiano relacionado con Tryonia metcalfi, una especie de caracol de agua dulce en peligro de extinción, endémica a un sistema de ciénagas en el oeste de Texas. Identificamos 14 familias bacterianas en nuestras muestras de caracoles y determinamos un conjunto principal de 19 taxones bacterianos; cuatro representan nuevos linajes, que probablemente dependen del caracol. En el futuro, los esfuerzos para proteger a T. metcalfi y su ambiente en consecuencia deben considerarla diversidad microbiana asociada con esta especie de caracol y la ciénega. [ABSTRACT FROM AUTHOR]

Issue: Lot accession information from natural history collections represents a potentially vital source of large datasets to test biodiversity, biogeography and macroecology hypotheses. But does such information provide an accurate portrayal of the natural world? We review the many types of bias and error intrinsic to museum collection data and consider how these factors may affect their ability to accurately test ecological hypotheses. Evidence: We considered all Texas land snail collections from the two major repositories in the state and compared them with an ecological sample drawn across the same landscape. We found that museum collection localities were biased in favour of regions with higher human population densities and iconic destinations. They also tended to be made during attractive temporal windows. Small, uncharismatic taxa tended to be under‐collected while larger, charismatic species were over‐collected. As a result, for most species it was impossible to use museum lot frequency to accurately predict frequency and abundance in an ecological sample. Species misidentification rate was approximately 20%, while 4% of lots represented more than one species. Errors were spread across the entire shell size spectrum and were present in 75% of taxonomic families. Contingency table analysis documented significant dependence of both misidentification and mixed lot rates upon shell size and family richness. Conclusion: Researchers should limit their use of museum record data to situations where their inherent biases and errors are irrelevant, rectifiable or explicitly considered. At the same time museums should begin incorporating expert specimen verification into their digitization programs. [ABSTRACT FROM AUTHOR]

This research explored the distribution, morphological variation, and molecular systematics of Elimia comalensis (Gastropoda: Pleuroceridae) using geometric morphometrics (n = 565) and mitochondrial DNA sequences (n = 15). Elimia comalensis was originally documented as endemic to Comal Springs, Comal County, Texas, but recent collections found this species in multiple springs and drainages in Central Texas. Morphometric analyses showed a high amount of morphological overlap with no clear geographic patterning. Phylogenetic analysis of mt COI sequence data indicated that E. comalensis represents a single species, with no genetic divergence among isolated populations. We conclude that E. comalensis may be an unrecognized native exotic, a species endemic to one area that has been spread by humans and assumed to be part of the natural fauna. [ABSTRACT FROM AUTHOR]

The lower Rio Grande Valley of Texas (LRGV) contains a unique, subtropical, semiarid floodplain with most of the few remaining Tamaulipan thorn forests in the United States. Less than 2% of Tamaulipan thorn forest remains, with urban and agricultural conversion potentially threatening diverse plant and animal communities native to the habitat. We performed vegetative community surveys and conducted a comprehensive survey of terrestrial snail communities in intact (refugia sites, minimally altered in recent times) and altered (previously cleared and regrown or restored) Tamaulipan thorn forest habitats of the LRGV. In a comparison of intact and altered sites that have comparable vegetation (paired sites), we found that intact sites had a less species-rich snail community than their altered counterparts, but this difference was not statistically significant. This counterintuitive result, in part reflects the fact that the most species-rich, intact snail communities (i.e., Sabal Palm Forest) have no altered (restored or regrown) counterparts and so were not included in the paired comparisons. A nestedness analysis supports this, finding that these unique intact sites, which have the highest species richness and no comparable restored sites, contain the largest pool of species in South Texas. Species richness of snails significantly correlated with a precipitation gradient. A general linear model incorporating mean canopy cover, mean plant height, plant abundance, and plant species richness shows a significant correlation with snail communities. This study is the only comprehensive survey of the snail communities of the lower Rio Grande Valley. [ABSTRACT FROM AUTHOR]

Pyrgulopsis Call Pilsbry, 1886 is a genus of small (<5 mm) spring snails, usually endemic to single freshwater springs. Two new populations of Pyrgulopsis found in very small, isolated springs and spring runs in the mainstem Rio Grande watershed of western Texas are distinguished from congeners. Mitochondrial and nuclear sequences, morphometrics, and morphological characteristics support Pyrgulopsis rubra sp. nov. and Pyrgulopsis harrymilleri sp. nov. as distinct from other known Pyrgulopsis species, including the geographically proximate P. metcalfi.

There are eight described species in Phreatodrobia, minute, phreatic (subterranean aquatic) snails, all stygobitic and endemic to the Edwards-Trinity Aquifer System of Texas. Two species were described from river drift (Pilsbry Ferriss 1906) and the others more recently by sampling the water flowing from wells or springs (Hershler Longley 1986b; Hershler Longley 1987). Recent sampling from spring orifices and the hyporheic zone of streams have extended the known ranges of the phreatic snails of the region and encountered unknown snails (Alvear et al. 2020). Here we describe Phreatodrobia spica n. sp., a rarely encountered species with a large range of about 400 km (Figure 1). We find P. spica in samples with a diverse assemblage of phreatic animals including other species of Phreatodrobia, isopods, amphipods, coleopterans, and mites. Phreatodrobia spica is distinguished from congeners using morphological and molecular evidence and is characterized by an elevated, trochiform shell with unique sculpture that include spikes and pustules. It has an open umbilicus and a complete, reflected lip that is sometimes appressed to the body whorl.