Accurate species identification is foundational to the management of introduced species. However, the current knowledge of the introduced hygrophilid snails in Japan, which is a hotspot of freshwater mollusks, is limited. We report the first record of Planorbella duryi (Wetherby, 1879) in Japan collected on two of the Bonin Islands, a World Heritage site.

Based on morphological examination of rock-, shell-, and coral-boring bivalves in the marine genus Botula, Wilson and Tait (1984) concluded that this genus comprised a single Recent species, Botula fusca (Gmelin, 1791), with a pan-tropical distribution spanning the western Atlantic, Pacific, and Indian Oceans. Variation in shell colour, habitat, depth, and anatomy were determined to reflect variation within this one species. In a subsequent review of Recent and fossil Botula, Kleemann (2007) expressed doubts about a monotypic Botula given “striking morphological differences” between several described species, advocating for the study of soft tissues and application of molecular tools to help resolve species identities. Here, for the first time, we have undertaken a molecular phylogenetic approach to explore species-level relationships within the genus Botula. Our taxon sampling included freshly collected specimens from the Florida Keys National Marine Sanctuary in the context of ongoing research into bioeroding bivalves at reef restoration sites, in addition to previous collections from the western Atlantic, Pacific, and Indian Oceans available at the Florida Museum of Natural History and the Santa Barbara Museum of Natural History. Based on analyses of mitochondrial (COI and 16S rRNA) and nuclear (H3 and 28S rRNA) genes, the genus Botula appears to be monophyletic, with the contentious species currently classified as Leiosolenus kleemanni (Valentich-Scott, 2008) falling within Botula rather than Leiosolenus. High levels of sequence differentiation among samples in this study, including ones previously identified as “Botula silicula”, Botula cinnamomea, “Leiosolenus” kleemanni, and Botula fusca, supported them as distinct species. Our phylogenetic analyses also identified a potential cryptic species within western Atlantic Botula fusca. Increased knowledge of diversity within the genus Botula should lead to a more accurate understanding of the role of these bioeroding species in reef ecosystems.

Discoveries of North American populations of the introduced terrestrial slug, Ambigolimax parvipenis, formerly treated as Ambigolimax nyctelius (Bourguignat, 1861), have increased in frequency over the last fifteen years. Most of these finds are occurring in the western United States of America. In 2015, a single specimen of A. parvipenis was collected in La Jolla, San Diego County, California, U.S.A. Here we report on an established population of A. parvipenis found in a residential backyard in San Diego, San Diego County and confirm through resampling that the single specimen collected in 2015 in La Jolla was not an incidental find.

The North American land snail tribe Stenotrematini (Emberton, 1995) is composed of 40 taxa from the genera Stenotrema (Rafinesque, 1819) and Euchemotrema (Archer, 1939). We conducted the first thorough examination of this group since 1948 by sequencing 196 individuals representing 31 of 40 members of the tribe using a combination of cytochrome c oxidase subunit I (COI) and a portion of the 5.8S gene of the large ribosomal subunit (LSU) with the accompanying internal transcribed spacer (ITS-2) region. We reexamined the validity of this tribe by incorporating new sequences with previous DNA work on the group and found strong support for both genera, but weak support for their sister relationship. We examined if species were well-circumscribed by comparing identifications based on shell morphology from a group of experienced land snail identifiers with three methods of species delimitation analyses (ASAP, bPTP, and SDA) applied to the COI dataset. All species delimitation analyses identified significantly more putative than described species. Further, there was disagreement in 52.5% of species between expert identification and monophyletic species-level clades. Part of the high number of putative species identified from species delimitation analyses may result from fragmented population structure, as among our two most heavily sampled taxa Euchemotrema wichitorum (Branson, 1972) and Euchemotrema leaii (A. Binney, 1840), the former had a strong signal of isolation by distance between populations and many more identified putative species than the latter, whose populations showed no pattern of isolation by distance. Lastly, we elevate Euchemotrema imperforatum (Pilsbry, 1900) to species based on a sister relationship with Euchemotrema hubrichti (Pilsbry, 1940) rather than Euchemotrema fraternum (Say, 1824) and highlight several additional species in need of further examination.

The terrestrial slug Deroceras reticulatum (Müller 1744) was used to examine if memory disruption could be restored by hormetic interventions. Hormesis is the process by which a potentially harmful stimulus elicits beneficial effects in the correct dosage and duration. From single-trial aversive stimulus conditioning, memory retention factor (Rf) was used to assess the effects of conditioning and oxidative damage via H₂O₂-injection at one day (Rf₁) and seven days (Rf₇), representing short- and long-term responses, respectively. Results from the conditioning showed a significant increase in Rf₁ in the experimental group compared to the control but not Rf₇. The induction of an oxidatively damaged phenotype was supported with significantly decreased Rf₁ in H₂O₂ injected-slugs compared to the saline-injected control. Calorie restriction (CR) and heat stress (HS) have been shown to extend lifespan in model systems, and they are thought to act, in part, through a hormetic mechanism. However, to our knowledge, the combination of both CR and HS has yet to be explored in the context of a systems-level assay, such as memory retention. HS and CR administered independently did not confer significant protection/recovery from oxidative damage. Co-administration of HS and CR similarly failed to offer significant protection/recovery from oxidative damage. Consequently, wild-caught phenotypically diverse terrestrial slugs used in the current study were susceptible to short-term conditioning (Rf₁), but not long-term conditioning (Rf₇), and oxidative damage from H₂O₂ was shown to disrupt memory. However, HS and CR had only a weak, non-significant effect on improving the disrupted memory phenotype.

In 2020, the freshwater mussels Louisiana Pigtoe Pleurobema riddellii (Lea, 1862) and Texas Heelsplitter Potamilus amphichaenus (Frierson, 1898) were categorized by the U.S. Fish and Wildlife Service as functionally extirpated/extirpated within the upper Sabine River basin of Texas and Louisiana with identified threats to population viability including changes in water quality. Purposes of this study were to update current knowledge (i.e., occurrences, relative abundances, catch per unit effort, and habitat associations) of Louisiana Pigtoe, Texas Heelsplitter, and other co-occurring mussel species within the Sabine River basin and to evaluate if water quality over a 50-year period could be a factor in the functionally extirpated/ extirpated categorization of Louisiana Pigtoe and Texas Heelsplitter within the basin. Surveys resulted in the collection of 28 freshwater mussel species and 9,244 individuals among 46 mesohabitats and five reaches of the Sabine River basin. Louisiana Pigtoe (n = 57) and Texas Heelsplitter (n = 7) were only observed in the upper Sabine. Louisiana Pigtoe was associated with swift current velocities, shallow depths, and gravel substrates. Texas Heelsplitter was associated with shallow, swift, riffle mesohabitats of sand and gravel substrates. Between 1960/1970s and 2020s, several water quality variables were generally within water quality standards and improved through time, indicating that water quality likely was not a limiting factor for freshwater mussels. Future monitoring is needed to further understand relationships between freshwater mussel communities and water quality.

Pecos assiminea (Assiminea pecos) is an endangered, little-known, cryptic microsnail occurring in moist karstic soil. Due to its small size and limited habitat preferences, research and population density estimates for this species have proven challenging. Here, we tested a range of survey methods and assessed their efficiency to capture microsnails and estimate their population density next to a sinkhole on Bitter Lake National Wildlife Refuge, Roswell, New Mexico, U.S.A. We used four different sampling methods: manual sifting and visual inspection of soil cores, light traps, beer traps, and Hester-Dendy plates. We also examined snail shells under different light wavelengths to test if they would become more visible, which they did not. We found most snails by sifting and visually inspecting the soil. Our estimations from manual sifting indicated that the population density of A. pecos is highest at around 3 m from the water's edge and 5–15 cm below the surface. Population density estimates at 3 m from shore were 6,200 snails per m². Furthermore, we found other snail species within our soil cores indicating that other microsnails utilize this habitat. Our method can aid studying A. pecos and other microsnails that live below the soil surface.

Discoveries of North American populations of the introduced terrestrial slug, Ambigolimax parvipenis, formerly treated as Ambigolimax nyctelius (Bourguignat, 1861), have increased in frequency over the last fifteen years. Most of these finds are occurring in the western United States of America. In 2015, a single specimen of A. parvipenis was collected in La Jolla, San Diego County, California, U.S.A. Here we report on an established population of A. parvipenis found in a residential backyard in San Diego, San Diego County and confirm through resampling that the single specimen collected in 2015 in La Jolla was not an incidental find.

Mirinaba curitybana (Lange de Morretes, 1952) is a Brazilian endemic land snail restricted to the surroundings of the city of Curitiba, Paraná state. Among the very few mentions of the species available in the scientific literature, there are three different spellings of the stem of its specific epithet. To address and solve this long-standing issue we reviewed all literature that ever cited the species and propose the adoption of the spelling Mirinaba curitybana. We also provide relevant comments on the form of citation of the author Frederico Lange de Morretes (1892–1954).

Examination of historical museum specimens coupled with modern samples can document faunal change over time. Samples from Big Lake in the Tippecanoe River watershed in northeastern Indiana were collected by Herman Wright in 1926–1927. Big Lake is one of the highest lakes in the watershed, so could be expected to be relatively pristine with little faunal change. From Big Lake samples, we identified 16 mollusk taxa (14,026 individuals) from 1926–1927 and 13 taxa (3,438 individuals) from 2020–2021, totaling 17 taxa in both time periods; relative abundances of taxa in the two time periods differed significantly (chi square, p < 0.001). Shannon diversity was smaller in the 1926–1927 sample (H' = 1.55) and slightly larger in the modern sample (H' = 1.80) despite more species found in the earlier time period, perhaps because species in the modern sample had greater evenness. Four species were relatively more abundant in samples from 2020–2021 than 1926–1927, Armiger crista (Linnaeus, 1758), Gyraulus deflectus (Say, 1824), Physella Haldeman, 1842, and Promenetus exacuous (Say, 1821), while two species were relatively less abundant in samples from 2020–2021 than 1926–1927, Galba humilis (Say, 1822) and Valvata bicarinata I. Lea, 1841 (p < 0.001 for all six comparisons). The invasive clam, Corbicula cf. fluminea (O. F. Müller, 1774), was present in the modern sample; its absence from the 1926–1927 samples is not surprising given its relatively recent introduction to North America. Four of five larger gastropod species were not found in 2020–2021, but due to low abundances in 1926–1927, their 2020–2021 absences are not statistically significant. We discuss faunal changes with respect to increased human activity and introduced crayfish and snail-eating fish. Additional survey work could address whether the larger species persist in low numbers.