The 2017 annual meeting of the American Malacological Society (AMS) was preceded by an iDigBio/National Science Foundation supported workshop on digitizing mollusk specimen data in non-federal Natural History Collections in the USA and Canada. The AMS President's Symposium invited mollusk researchers, curators and collection managers, who are creating and employing digital specimen data in research to highlight the many new avenues that are opening up due to the growing landscape of digital data available. Here we describe the symposium, the workshop, and the workshop outcomes. Among the priorities identifi ed were imaging of primary types, expanding taxonomic authority fi les and initiating collaborative georeferencing.

In 2017, a minimum of 8.5 million mollusk lots representing some 100 million specimens were held by 86 natural history collections in the U.S. (81) and Canada (5). Of these, 6.2 million lots representing 70 million specimens were cataloged (73%), another 2.3 million lots were considered quality backlog awaiting cataloguing, and 4.5 million lots (53% of the total) had undergone some form of data digitization. About 1.1 million (25%) of the digitized lots have been georeferenced, albeit with different approaches to accuracy and uncertainty. Fewer than 25% of collections, mainly larger ones, claim to be fully Darwin Core compliant. There are 35,000 primary type lots and 66,000 secondary type lots, representing 1.6% of cataloged lots. About 87% of lots are dry and 13% are fluid preserved, with less than 0.3% frozen. The majority of lots are gastropods (71%) and bivalves (26%). By habitat, 54% of lots are marine, 26% terrestrial, 19% freshwater, and 1% brackish. About 43% of marine and 57% of non-marine holdings are from North America including the Caribbean.

Solem (1975), in a previous survey of U.S. and Canadian malacological collections, reported 3.74 million lots of which 775,000 (21%) were uncataloged backlog, and suggested that backlog was growing at a faster rate than specimens were being cataloged. Since then the overall size of mollusk collections has grown by 227% and cataloged lots by 208%, but quality backlog has grown by 300%, confi rming Solem's extrapolation. Solem noted that the eight largest collections held 78% of the lots, but in 2017 the eight largest (now with a slightly different composition) held only 63.5% of the lots, refl ecting substantial growth of small and mid-sized collections, and the larger number of institutions that we surveyed. Solem reported a substantial gap between large collections (≥160,000 lots; AMNH, ANSP, BPBM, DMNH, FMNH, LACM, MCZ, UF, UMMZ, USNM) and mid-sized ones (35,000-75,000 lots; ChM, FWRI, Hefner, HMNS, SDNH, NCSM, SIOBIC, UCM, UWBM, YPM), but seven collections now fall in the range of 76,000 to 160,000 (CM, BMSM, CASIZ, CMNML, INHS, OSUM, and SBMNH), and two have jumped to the large category (UF and DMNH).

Often overlooked is Solem's conclusion that mollusk collections in the United States and Canada are second only to insect collections for number of specimens, which is still true. Because there are far fewer species of mollusks than insects, mollusks have more specimens per species, averaging 1,100 in our survey, almost ten times what Solem reported for insects and approaching what he reported for fish. Bivalvia may have as many as 2,400 specimens/species, which makes them among the best-sampled classes of metazoans. The high number of specimens/species among mollusk and fish collection makes them well-suited for environmental studies that track faunal change over time and space.

A growing use of natural history collections is documenting changes in species distributions, morphology, phenology and genetics during historical times. Until the 20th century, however, collecting dates were not routinely recorded in collections, making it difficult to determine the time course of biotic changes. Various forms of proxy data can constrain when a particular sample might have been collected. The date of cataloguing puts an upper limit on potential collecting dates, as do dates of death of agents such as collectors, donors, and other previous owners, and dates of birth and activity of collectors give a lower limit. Archival material such as field notes and acquisition records can also provide constraints. Information in such sources should be captured in standardized biographical databases to allow automated bounds on collecting dates to be applied via fields in collection databases. Mollusks are among the best sampled metazoans, so they can serve to test the effectiveness of using biographical data to constrain collecting dates. A random sample of records in the ANSP malacology database that lack date of collection shows that when an agent is known, date of death information improves on date of cataloguing as a constraint on collecting date for 41% of records. Overall, including records that lacked agent information, 38% had improvement. If further historical information such as dates of travel, residence, employment and other affiliations were included in biographical databases, additional improvement on these bounds could be obtained. Collection databases need appropriate data structures for provenance information to track the chain of ownership of specimens more rigorously, and to allow cleaner interface with biographical databases. A survey of other large mollusk collections in the United States suggests that a similar level of improvement could be obtained more generally, affecting millions of specimens. If this result could be extended to other disciplines, a substantially increased proportion of specimens in natural history collections would be accessible for studies of biotic change. Interoperability with genealogical databases could accelerate addition of provenance data to natural history databases.

Terrestrial gastropod inventories can be improved, both in scope and thoroughness, by including species observations made by citizen scientists. Few citizen science projects, however, focus on terrestrial gastropods and perhaps none has mobilized members of the public to survey the malacofauna of a major North American metropolitan area. Here we report first occurrence records of five introduced terrestrial gastropod species in the metropolitan areas of Los Angeles, Orange, and Riverside counties in California, discovered by citizen science: Arion hortensis Férussac, 1819, Cochlicella barbara (Linnaeus, 1758), Lauria cylindracea (Da Costa, 1778), Pupoides albilabris (C.B. Adams, 1841), and Xerotricha conspurcata (Draparnaud, 1801). Four of these taxa are known elsewhere in California and one, L. cylindracea, is a first occurrence record for the U.S.A. All were contributed to SLIME, a citizen science project and malacofaunal inventory of southern California initiated by the Natural History Museum of Los Angeles County and hosted online by iNaturalist. Species identifications were made based on snail or slug morphology and collected specimens' COI barcoding sequences, which were compared to those in GenBank and BOLD databases. These discoveries demonstrate the efficacy of SLIME and the potential for molluscan-focused citizen science to detect and document land snail and slug taxa in a major metropolis.

Research on molluscan specimens is increasingly being carried out using high-throughput molecular techniques. Due to their efficiency, these technologies have effectively resulted in a strong bias towards genotypic analyses. Therefore, the future large-scale correlation of such data with the phenotype will require a significant increase in the output of morphological studies. Three-dimensional (3D) scanning techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) can achieve this goal as they permit rapidly obtaining digital data non-destructively or even entirely non-invasively from living, fixed, and fossil samples. With a large number of species and a relatively complex morphology, the Mollusca would profit from a more widespread application of digital 3D imaging techniques. In order to provide an overview of the capacity of various MRI and CT techniques to visualize internal and external structures of molluscs, more than twenty specimens ranging in size from a few millimeters to well over one meter were scanned in vivo as well as ex vivo. The results show that all major molluscan organ systems can be successfully visualized using both MRI and CT. The choice of a suitable imaging technique depends primarily on the specimen's life condition, its size, the required resolution, and possible invasiveness of the approach. Apart from visual examples derived from more than two dozen scans, the present article provides guidelines and best practices for digital 3D imaging of a broad range of molluscan taxa. Furthermore, a comprehensive overview of studies that previously have employed MRI or CT techniques in malacological research is given.

The reproductive cycle, stages of gonadal development, and minimum size of sexual maturity are described for a population of the clam Donax punctatostriatus Hanley, 1843 from a sandy beach in southern Sinaloa, Mexico. A total of 880 clams were collected from January 2009 to June 2010; 3.2% were sexually undifferentiated and 1.4% had the trematode parasite Postmonorchis sp, in the gonadal tissue. The total length of the clams ranged from 3.5–25.64 mm ( = 13.51, S.D. = ±4.47 mm). The sexual proportion did not differ significantly from ♀1:1♂ (p > 0.05). The minimum size at sexual maturity (L₅₀) was L₅₀ = 12.03 mm. The gametogenic cycle comprise six stages of gonadal development (0-V). The population is reproductively active throughout the year and spawning is continuous, with three major peaks in April, July and September 2009. In March, when the water temperature was between 21–23 °C, most individuals were in stage I. This period is characterized by a rapid maturation of gametes. At the end of October and during November, when water temperature was warmer (25–28 °C), 50% of the individuals were in stage V (spent). Recruitment was more intense from July to October of 2009, when the highest temperatures of the year were recorded (28–31 °C). Photoperiod and the proportion of mature individuals of both sexes were significantly correlated (Pearson's correlation value = 0.62; p < 0.05). Since this clam is a potential resource for human consumption, the information here presented may contribute to a better management and use of their populations in the Mexican Pacific.

Ascidiella aspersa (Muller, 1776) is an exotic tunicate species widely distributed along the Sud-Occidental Atlantic coasts. In Patagonia waters, it forms dense aggregations at El Sótano (San Matías Gulf). We report an undescribed association between this invasive tunicate and a native mytilid species, Musculus viator (d'Orbigny, 1842). During a benthic study, a total of 543 individuals of A. aspersa were collected at El Sótano. A total of 689 individuals of M. viator were extracted from the tunics of 42 A. aspersa specimens. A maximum of 50 mytilid per tunicate was found. No relationship was found between the size of the tunicates and the size of M. viator. The prevalence of M. viator on A. aspersa individuals suggested that the tunicate invasion might have altered the community structure by improving local physical conditions -alternative substrate or refuge- for mytilid populations.

The cryptic invader, Ferrissia californica (Rowell, 1863) (Gastropoda: Planorbidae), was identified using specimens collected in freshwater streams on Montserrat, West Indies using mtDNA sequences. This is the first record of a freshwater limpet from Montserrat and the third ancyline reported from the Caribbean. Freshwater limpets are small and difficult to find, which suggests that they are present on other islands, and the morphological plasticity of Ferrissia spp. suggests that published records of freshwater limpets from the Caribbean may include misidentified species.