Reproductive investment theory assumes that females invest more in mate choice than males do because eggs are more energetically costly to produce than sperm. However, recent studies indicate that the relationship between initial investment and patterns of sexual selection is more nuanced. Simultaneous hermaphrodite mating systems offer unique opportunities to explore reproductive investment theory, as individuals exhibit fluid preferences for donating or receiving sperm and eggs. Shifts in gender role can depend on environmental or physiological conditions such as size. However, environment factors (e.g. temperature) that affect mating role preference or behavior (e.g. latency to copulate, reciprocity) have not been explored, despite evidence that the physiological consequences of elevated temperature interfere with reproductive success. By constraining the amount of energy available during copulation, elevated temperature may directly impact individual investment, reflected in changes in gender role. We observed courtship and gender roles in Physella acuta (Draparnaud 1805) at standard (19-20°C) and elevated (28-29°C) temperature. Elevated temperature reduced duration and frequency of copulation but had no effect on latency to copulate or reciprocity. Contrary to previous studies, gender role was not found to be size-dependent in either temperature treatment. Lack of size dependence across temperature treatments could be due to low population density or climate in situ. Combined results indicate that although elevated temperature clearly has negative physiological consequences, its impact is not reflected in changes to gender role patterns. This relationship is more complicated than previously expected and requires further study.

The ecological role of large thecosome pteropods in the pelagic ecosystem of the northern Gulf of Mexico (GoM) may be substantial, both in the food web and biogeochemical cycling. We analyzed species abundances, vertical and horizontal distributions of large species with calcareous shells (those collected in 3-mm mesh nets). Pteropod samples were collected following the 2010 Deepwater Horizon oil (DWH) spill by two midwater sampling programs: the Offshore Nekton Sampling and Analysis Program (ONSAP 2011) and the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND 2015) projects. All samples were collected using a 10-m² Multiple Opening/Closing Net and Environmental Sensing System (MOC10) midwater trawl, with 3-mm mesh. This gear sampled five discrete depths between 0–1500 m. Over 13,000 pteropod specimens were examined, with 25 species identified. Clio pyramidata Linnaeus 1767 was the most abundant species during both collection periods. Five genera (Diacria, Clio, Styliola, Cuvierina, Cavolinia) demonstrated diel vertical migration from the mesoto epipelagic zone.

Scientific names that refer to people are called eponyms and are chosen by species authors as honorific, meaningful, or symbolic. Herein, female and male personal eponyms were analyzed from a dataset of 4,915 molluscan species within eight regions worldwide. Eponyms were 12.5% of all species names, within which 10.6% (n = 65) were female and 89.4% (n = 550) were male. Among gastropods, female eponyms accounted for 3.4–18.9% of eponymous species names; male eponyms were 81.1–96.6%. Among bivalves, species names within five of eight regions included no female eponyms. Cephalopod and chiton species included 22 male eponyms and no female eponyms. Scientists and naturalists were honored as the source of 29.2% of female eponyms and 64.6% of male eponyms. First names were the source of 63.1% of female eponyms and 4.6% of male eponyms. Last names were the source of 93.8% of male eponyms and 35.4% of female eponyms. The most eponyms for a woman (n = 4) honor 20^th century American malacologist, A. Myra Keen; the most eponyms for a man (n = 6) honor two 19^th century English naturalists, Thomas Nuttall and Robert Swinhoe. Gender asymmetry in molluscan eponyms likely reflects barriers to women's participation in malacology, taxonomy, and systematics until the late 20^th century. Recognition of this inequity should inform discussions about female representation in scientific names and provide context for understanding the history of eponyms and the people they honor.

The density, dispersion, size, growth, longevity, natural mortality, and recruitment of Chama coralloides Reeve, 1846, a bivalve captured in artisanal fisheries, were studied. Sample collection was carried out in November 2016, March 2017, and February 2018 at eight sites in the rocky intertidal zone, located in the south-central region of the Mexican Transitional Pacific. Using a 1 x 1 m quadrat, 10 random quadrats were conducted at each site. Density was determined with Pennington's method of Δ distribution. The dispersion was estimated with the Morisita index and modal groups with multinomial analysis. Growth, natural mortality, and recruitment parameters were estimated with FiSAT II. Variable density between sampling dates and sites was observed, with the highest densities found at sites 1 and 4. The largest interquartile range of lengths was observed at site 6, and the smallest at site 5. Five modal groups were determined in November 2016 and March 2017, and four in February 2018. Estimated growth parameters were L_∞= 74.5 mm and K= 0.63; longevity was A_.95 = 4.4 and A_.99= 6.9 years, growth performance index ∅′= 3.5 and natural mortality M = 1.05 yr^–1. Continuous recruitment was observed with a maximum peak in summer.

Freshwater mussels are important components of aquatic systems, where they cycle nutrients, stabilize streambeds, increase niche habitats, and are sources of food for mammals, birds, fish, and aquatic invertebrates. The biogeographically distinct Ozark Highlands is one of the oldest terrestrial regions on the planet and is home to over 200 endemic species including freshwater mussels. Key to the conservation and management of this mussel fauna is documenting their distribution and determining if any changes have occurred. In this study, our objectives were to document the diversity and distribution of the mussel fauna of the Missouri portion of the Eleven Point River, a National Wild and Scenic River, and determine if any changes had occurred over a 25+ yr period. During 1982–1985 and 2012–2019 we surveyed 29 locations, including 12 surveyed during both periods, in summer to early fall, during low flow conditions with timed visual and tactile searches. We calculated metrics to measure the status, composition, and abundance of the mussel community, and examined the rate populations were experiencing extirpation or colonization. Historically, 21 freshwater mussel species were known from Eleven Point River; 20 were observed live or as shell material in the present surveys. During both surveys, the Eleven Point River basin was dominated by members of the Lampsilini, which exhibit periodic life history strategies. We detected significant declines in the number of live individuals, CPUE, and richness at the 12 resurveyed locations. Freshwater mussel species in the Eleven Point River are being extirpated at a significantly higher rate than colonizing areas of the Eleven Point River. Causes for this decline remain unknown.

As a major tributary to the species-rich Ouachita River and one of the few remaining non-channelized rivers in the Alluvial Plains physiographic division, Bayou Bartholomew is a key ecosystem for the freshwater mussel diversity of southeast Arkansas and northeast Louisiana. Bayou Bartholomew is known to contain 16 mussel Species of Greatest Conservation Need (SGCN) but the mussel assemblage of the Louisiana section of Bayou Bartholomew has not been assessed since the early 2000s. In 2021, we sampled over 100 river km on the main channel of Bayou Bartholomew and four tributaries from just downstream of the Louisiana/Arkansas border to the confluence with the Ouachita River. We used a novel two-phase timed-search protocol to characterize the mussel assemblage and measured shell length (long axis) to determine the size distribution of each species encountered. A suite of relevant habitat variables and site attributes were also quantified or qualitatively noted. One site was selected for sampling using a grid survey to determine quantitative estimates of mussel density. Our survey confirmed the presence of 35 species including 12 SGCN in the Louisiana section of the Bayou Bartholomew drainage. In total, 3,292 live mussels representing 33 species were collected in the main channel, 234 live mussels representing 18 species were found in a quantitative grid, and four species were found in tributaries. Two additional species were only found in tributaries as dead shells. Length frequencies of all common and abundant species indicated ongoing annual recruitment. Patterns of ubiquity in the main channel of Bayou Bartholomew varied by species, and mussels were rare in the tributaries. Generalized linear modelling and non-metric multidimensional scaling analyses identified relationships between mussel assemblage composition and the distance from the confluence with the Ouachita River and habitat variables including substrates, depth, and mesohabitat types. A comparison with previous studies did not provide any evidence of major changes in overall mussel species distributions or occurrence in Bayou Bartholomew in Louisiana. We attribute the apparent stability in the mussel assemblage to the fact that major anthropogenic alterations such as channelization, impoundments, and watershed urbanization have been minimal since the earlier studies, and we conclude that Bayou Bartholomew will likely continue to be a hotspot of regional mussel diversity and a haven for several of Louisiana's SGCN if large-scale anthropogenic alterations to the system do not occur and management actions are taken to protect and allow for the persistence of heterogenous habitats.

The worm slug Boettgerilla pallens Simroth, 1912, is reported in Washington State for the first time with records from King, Pierce and Snohomish counties.

Rocky Mountainsnails in the genus Oreohelix go mostly unnoticed beneath layers of leaf litter in the Rocky Mountains and sky islands in the American intermountain west. Oreohelix strigosa (Gould, 1846) is one of the most widespread species in this genus, common in rocky foothill habitat that consists of high-density groves of deciduous maple or oak. While many people consider terrestrial snails as garden pests, many western snails are considered detritivores, feeding primarily on decomposing plant matter. As the trophic ecology of O. strigosa remains poorly understood, we investigated if O. strigosa is primarily a detritivore by providing three groups (10 snails) two food sources (Boxelder maple leaf litter and fresh romaine lettuce) and examining fecal matter. Our results indicate that O. strigosa primarily consumes leaf litter, highlighting that O. strigosa, and likely other Oreohelix snails, are detritivores. This insight should aid future conservation efforts as their habitat continues to be threatened by development.

Sineancylus rosanae (Gutiérrez Gregoric, 2012) is a freshwater limpet that has its apex located along midline on the anterior side of shell, different from other species of Ancylinae. Previously, it was considered a species of Laevapex in the Brazilian states of Paraná and Rio Grande do Sul. Agudo-Padrón (2007) also mentioned Laevapex sp. without giving a precise locality or an image of the material in question. Therefore, it is unknown if this record was really a Laevapex species or a misidentified Sineancylus. Due to its rarity, limited distribution, and its peculiar characters, herein we provide a proper record of S. rosanae from the state of Paraná, Brazil, expanding its known distribution. A population of S. rosanae was discovered in the Ocoí River (municipality of Medianeira) attached to basalt stones in the middle of the river. The shells analyzed in this study closely fit the original description.