Florida United Malacologists 2019


Investigating the Association of Arca zebra and Hard Corals in the Gulf of Mexico

Abigail Bridges and Gregory Herbert

School of Geosciences, University of South Florida, Tampa, FL 33620


In the Gulf of Mexico, there are few areas in which coral reefs are present. These areas are situated along the Florida Keys, the Yucatan and Veracruz areas of Mexico, and in the Flower Garden Bank National Marine Sanctuary near Texas. Corals outside of these areas must find basibionts or other hard surface in order to survive. The mollusk, Arca zebra, is one of the hard-shelled organisms that provide coral polyps a point of attachment in an environment that otherwise lacks hard substrate; however, little is known about the symbiosis between corals and A. zebra and whether the association may be driven by the clumping behavior, longevity, or shell size of A. zebra. Samples were collected from the Gulf of Mexico, ranging from Cedar Key to Dry Tortugas, over the course of a decade. The locations in which these species were collected will be mapped using ArcGIS and compared against the distribution of corals within the Gulf of Mexico. While this study is still in its infancy, preliminary data indicate that coral is attaching to A. zebra that were collected near mid and northern Florida despite this being the range limit of the species.


Paleoenvironmental Reconstruction and Pre-Columbian Shellfish Gathering on a Barrier Island along South Florida’s Atlantic Coast

Arlene Fradkin

Department of Anthropology, Florida Atlantic University, Boca Raton, FL


Palm Beach, a barrier island along South Florida’s Atlantic coast, is separated from the mainland by Lake Worth Lagoon, a brackish water body today but historically an enclosed freshwater lake. Site 8PB28, a pre-Columbian archaeological site, dating from A.D. 500 to 1,000, is situated in the island’s northern section, immediately adjacent to the lagoon.  The faunal assemblage is overwhelmingly predominated by molluscan remains, constituting 99 percent of the minimum number of individuals.  Only brackish and marine species are represented, indicating that Lake Worth Lagoon was brackish rather than freshwater during the time of occupation and that the pre-Columbian site inhabitants were collecting shellfish from both the lagoon and nearby Atlantic Ocean coastal waters.


Florida United Malacologists (FUM) at 10

Alan Gettleman

2225 Tanglewood Lane, Merritt Island, FL 32953


Two amateur citizen scientists conceived the idea of bringing a one day meeting to Florida of scientists, students, and all those interest in the mollusks.  The meeting was based upon other existing groups, viz. Southern California United Malacologists (SCUM); Ohio Valley United Malacologists (OVUM), and Mid-Atlantic Malacologists (MAM).  Discussed will be the process of generation for the original meeting and a brief look at the annual presentations.


Decline of reef resilience and ecosystem services in one of the last “pristine” oyster habitats of North America

Gregory S. Herbert1, Stephen G. Hesterberg2, Thomas Pluckhahn3, and Ryan M. Harke3

 1School of Geosciences, University of South Florida, Tampa, FL, 33620; 2Department of Integrative Biology, University of South Florida, Tampa, FL, 33620; 3Department of Anthropology, University of South Florida, Tampa, FL, 33620

The northern Gulf of Mexico ecoregion has been identified as the last opportunity to achieve sustainable oyster habitat in North America.  However, baseline data needed to assess habitat condition were collected only after 1950 and likely represent already-degraded reference states.  Comparison of prehistoric and modern oysters from Crystal River, FL, an area previously identified as “pristine,” reveals loss of large size classes before historical records began. Isotope sclerochronology profiles from large modern and prehistoric shells show similar first year growth patterns, but modern oysters exhibit slower growth after year one and suffer early mortality. Loss of large oysters and shortening of life history are consistent with declines in critical, size-dependent ecosystem services (e.g., filtration), recruitment, and reef resilience. Our study shows how deep time archives can help correct the generational amnesia that gives rise to reduced expectations for and neglect of coastal ecosystems.


Examining 3D radula morphology and function in drilling and non-drilling gastropods using synchrotron radiation x-ray microtomography

Stephen Hill*, Jen A. Bright, Gregory S. Herbert

School of Geosciences, University of South Florida, 4202 E. Fowler Avenue, NES 107, Tampa, FL 33620

The Neogastropoda are a large radiation of approximately 16,000 marine snails, of which the family Muricidae comprises roughly 10%. Muricids are notable for the presence of predatory drilling behavior, where the snail will bore through the shell of its prey using the radula. It has therefore been hypothesized that drilling species should possess more robust radulae to cope with the higher mechanical stresses associated with drilling predation, but the small size of these structures has made quantification of the morphology, and tests of the functional hypotheses, difficult to conduct. We obtained high-resolution three-dimensional (3D) tomographic scans of drilling and non-drilling Neogastropod species at the European Synchrotron Radiation Facility (ESRF). These scans were used to generate 3D digital representations of the rachidian (central) tooth of each species. Such models can then be subjected to linear and geometric morphometric methods to quantify overall morphology and functionally relevant traits and used to develop mechanical (Finite Element) models to provide quantitative data on their structural performance during feeding. Our imaging reveals previously unappreciated 3D features associated with the articulations between teeth. In particular, we find several structures on the tooth cusps and tooth bases, possibly indicative of functional interaction among the teeth during feeding.


Childhood on the Rocks

William F. Keegan

Curator of Caribbean Archaeology, Florida Museum of Natural History, 1659 Museum Road, Gainesville, Florida 32611

Children are important members of all communities, yet they remain largely invisible in archaeological research. The paper addresses, for the first time, the role of children in mollusk foraging in an entirely pre-Columbian context. Surprisingly, archaeologists have considered mollusk foraging to have been insignificant during Saladoid times (circa 500 BC to AD 600). Yet a considerable number of small mollusks were recovered from midden deposits at the Saladoid Main Street KPG site on St. Thomas, USVI (cal. AD 400). During excavations conducted in 2014 we identified 2,832 gastropods representing at least 25 Families, 36 genera, and 42 species; and 1,396 bivalves representing at least 18 Families, 29 genera, and 29 species. These mollusks inhabit rocky intertidal and shallow patch reef/seagrass environments; they are found in shallow water, are not deeply buried in sandy and seagrass environments, and/or adhere to rocks, reefs and other hard substrates (e.g., mangrove roots).  With water depth as a potential limiting factor, all of these habitats are easily accessible to children.  The abundance, diversity, ease of capture, portability and other characteristics are used to attribute this assemblage to foraging by children. Not only were mollusks important, they provide a window into the past that is otherwise inaccessible.


The Response of the Wakulla River Molluscan Communities to Hurricane Michael: Climatic Impacts and Invasive Species 

Kristopher Kusnerik*1, Guy H. Means2, Ryan C. Means3, Roger W. Portell1, and Michal Kowalewski1

Florida Museum of Natural History, University of Florida, 1659 Museum Road, Gainesville, FL 32611, 2Florida Geological Survey, 3000 Commonwealth Boulevard, Suite 1, Tallahassee, FL 32303, 3 Coastal Plains Institute, 46 Kinsey Road, Crawfordville, FL 32327


Human-based activities, both direct and indirect, have had drastic effects on the health and diversity of Florida’s freshwater spring and river ecosystems. These include the introduction of invasive species and upstream migration of brackish/marine species into previously freshwater areas, and upstream retreat of freshwater species. These upstream shifts are driven by rising sea levels amplified by surges from hurricanes and storms. Hurricane Michael made landfall in Florida on October 10, 2018, bringing severe storm surges and other effects. In the specific case of the Wakulla River, the hurricane flushed brackish waters upriver as far as the headspring. Using subfossil (Holocene) mollusk records as well as live mollusk samples collected pre- and post- storm, we documented the response of Wakulla’s freshwater communities to Hurricane Michael’s storm surge and compared these communities with freshwater fossil assemblages recording pre-human climatic conditions. Fossil deposits present along the river’s length record 18 species (all native). Pre-storm modern diversity had dropped to seven species, including two invasive species and one brackish gastropod. Following the storm, the diversity remained the same, but the relative abundances of many species shifted. The brackish gastropod was found further upriver than before the hurricane. Additionally, relative abundances of native species dropped in relation to invasive taxa. The lack of brackish species in the fossil record suggests this encroachment of salinity-tolerant species is a recent development, likely reflecting the rising sea levels and resulting upstream surges of marine waters. Additionally, invasive taxa seem more resilient than native taxa, either recovering faster or being less affected by salinity surges. These trends suggest native taxa are at elevated risk as sea level continues to rise, and frequency and severity of hurricane events increase.


The Bailey-Matthews National Shell Museum Digital Imaging Project

José H. Leal

Bailey-Matthews National Shell Museum, 3075 Sanibel-Captiva Road, Sanibel, FL 33957 USA


The Bailey-Matthews National Shell Museum collection (BMSM) currently encompasses about 128,300 catalogued lots. As part of our efforts to disseminate collection data to remote users, the Museum has embarked in an ambitious project that includes acquisition, processing, storage, and distribution of images of selected collection specimens and related objects (e.g., original labels, notes). The new endeavor is the logical sequel to a critical, two-phase project funded by two IMLS (Institute of Museum and Library Services) Collection Stewardship grants that allowed for the cataloguing of the entire BMSM backlog over a period of five years. We will, conforming to Darwin Core and Audubon Core standards, link images to the BMSM catalogue via iDigBio* and, ultimately, to other collection data aggregators. The main objective is to capture and distribute images of 9,240 specimens representing about 6,850 species from key areas of the collection, with distinct emphases on types, vouchers, the Colin Redfern Collection (Bahamas), Southwest Florida, Florida in general, and parts of the Eastern Seaboard of the US. The 2.5-year project, funded in late 2018 by IMLS Collections Stewardship Grant MA-30-18-0438-18, was just launched, with the acquisition of photographic equipment, graphics-oriented computer, image-capture and processing software, and the recent hiring and training of specialized staff.

*iDigBio https://www.idigbio.org/portal/recordsets/b40e13f7-a79a-4265-93d9-3b4878dfc988; *Global Biodiversity Information Facility (GBIF) https://www.gbif.org/publisher/1c8732e1-36b1-4a7c-978e-f69542768ec3


Heterobranch homoplasy: skeneid and tornid imposture

Harry G. Lee

Since Aristotle, investigators have been relatively neglectful of the smallest molluscan shells. However, over the last three decades, a cadre of intrepid malacologists have put this element of the global fauna under scrutiny. As a consequence, along with the spate of taxa described, new insights into the biology of these tiny mollusks have led to major shifts in the systematic paradigm. Based on holistic analyses, many new, and a number of familiar “old,” species of skeneiform snails have been found to belong in the Heterobranchia rather than the Vetigastropoda, e.g., Skeneidae, and Caenogastropoda, e.g., Tornidae, where they had been or might have been placed. I have come across such exemplars of homoplasy (convergence) in both the fossil and Recent fauna, most found in Florida. The majority of these taxa appear to have affinities with recently described genera but are apparently undescribed species representing new records in space and time at both the generic and specific levels. Focusing on conchology, I shall discuss these novel taxa and the phenomena of hyperstrophy and heterostrophy in gastropod shell coiling as they relate to the evolution, phylogeny, and a more informed taxonomy for this cohort.


So—You Think You Want to Write a Shell Book

Carole P. Marshall

932 Cochran Drive, Lake Worth, Florida 33461

A somewhat humorous tongue in cheek primer in case you think you might want to write a book on seashells.  What to expect, what to avoid and some very important steps to take. What you need to learn and what you need to buy and some good advice I received.


“When Junonias Attack!”

Rebecca Mensch and José Leal

The Bailey-Matthews National Shell Museum, 3075 Sanibel-Captiva Road, Sanibel, FL 33957

First record of the Junonia (Scaphella junonia) strike on its prey, the Lettered Olive (Americoliva sayana). Three live Junonias were collected during a Gulf of Mexico expedition (GS Herbert, Chief Scientist) in February of 2018. The animals are on loan to the Bailey-Matthews National Shell Museum for research, where they are maintained in a saltwater aquarium. Video of the strike illustrates the need for future research on any substances used by the Junonia during the strike, as well as the Lettered Olive’s defense mechanism.


Florida’s Cenozoic Cephalopods: Occurrences and Preservation of the genus Aturia

Carmi Milagros Thompson, William H. Dean, Roger W. Portell

Florida Museum of Natural History, 1659 Museum Road, Gainesville, FL 32611

Though uncommon, the nautiloid Aturia occurs in many of Florida’s late Eocene through middle Miocene deposits. Despite documentation and continued collection, most Aturia lack formal study and description. Here, we focus on the presence of the genus in the lower Oligocene Suwannee Limestone, as individuals recovered from this deposit possess unusual preservation and a highly restricted spatial distribution.  While Oligocene deposits near the land surface are common across most of central and northern Florida and rich with invertebrate fossils, reports of nautiloid occurrences in these deposits are recent. This may be due in part to under-sampling, but also to composition of the organism, as nautiloid shells are aragonitic and preserve poorly in limestone. Approximately 50 individuals have been collected from the Suwannee Limestone, all of which occur at a single locality along the Withlacoochee River. At this one locality, Aturia preserves as recrystallized phragmocones inside silicified concretions. These individuals are mostly intact, but lack the living chamber, and generally range between 20 – 60 mm in size.


Investigating Temporal and Spatial Biodiversity of Mollusks on the Western Shelf of Florida Using Taphonomic Grading

Nicole Seiden and Dr. Gregory Herbert

School of Geosciences and Paleobiology, University of South Florida Tampa, FL 33620 USA


The Gulf of Mexico spans 1.6 million km2 and is one of the most economically and ecologically important bodies of water in the United States, Mexico, and Cuba; however, it is under increasing threat from human activities (e.g., pollution, fishing, and mining). While still in the early stages of development, this study seeks to identify priority conservation areas in the eastern Gulf. To answer this question, we will analyze a new dataset based on marine mollusks collected from seafloor sampling of 230 stations that span nearly the entire western Florida shelf from 2008 to present. Collections can be partitioned into pre- and post- 1950 using shell condition (i.e., taphonomy) as a proxy for age. Mollusks were selected for this study because of their abundance and presence of dead individuals that represent past communities. Preliminary data indicate that some species have disappeared from habitats in which they were previously abundant, and biodiversity and species populations are not continuous but are clumped in specific hotspots.


Fossil cassids (Mollusca: Gastropoda) from the upper Eocene Ocala Limestone of Florida

Shamindri Tennakoon1,2*, Roger W. Portell1, Michal Kowalewski1, Elizabeth Petsios3 and Carrie L. Tyler4

1Florida Museum of Natural History, University of Florida, Gainesville, FL 32611

2Department of Biology, University of Florida, Gainesville, FL 32611, 3Department of Geosciences, College of Arts and Sciences, Baylor University, Waco, Texas 76798, 4Department of Geology and Environmental Earth Science, Miami University, Oxford, OH 45056


Cassid gastropods feed on echinoids, producing distinct drill holes. Traces resembling cassid drill holes are common in the fossil record, however, cassids are an underexplored group of gastropods. Although echinoids with traces resembling cassid drill holes are common in the upper Eocene Ocala Limestone of Florida, cassids are rare. As part of a larger project, we aim to resolve the taxonomy of cassids from the upper Eocene Ocala Limestone, using specimens reposited in the Invertebrate Paleontology Division, Florida Museum. Morphological characters, linear measurements, and additional variables were recorded using specimens and RTV silicone rubber peels. Two morphotypes were identified. Morphotype 1 resembles the described cassid from the Ocala Limestone, Phalium globosum Dall, 1890, and morphotype 2 resembles modern Semicassis spp. High variability is observed in specimens belonging to morphotype 2, suggesting a gradient in shell ornamentation. Ordination plots from multivariate analyses also suggest high morphological variability amongst specimens belonging to morphotype 2. In the specific example of Florida Eocene cassids, the integrative use of qualitative and quantitative morphological data improved our ability to assess morphological variability within the group. The results suggest that a minimum of two distinct cassid morphotaxa are present in the upper Eocene Ocala Limestone of Florida.


How has the Hawaiian endemic land snail genus Auriculella fared after a century of obscurity during an extinction crisis?

John Slapcinsky1, Kenneth A. Hayes2 and Norine W. Yeung2

1Florida Museum of Natural History, 345 Dickinson Hall, Gainesville, FL 32611, USA

2Bishop Museum, 1525 Bernice St., Honolulu, HI 96817, USA

Although isolated in the central Pacific, Hawaii has an extraordinarily diverse land snail fauna with at least 750 endemic species, most of which are restricted to single islands or mountain ranges. Achatinellidae is the second largest Hawaiian land snail family with 209 species in five subfamilies, two of which, the Achatinellinae and Auriculellinae, are endemic to Hawaii. While the large and colorful Achatinellinae have garnered significant research. The Auriculellinae, have remained little studied. This lack of knowledge is alarming because the introductions of non-native species, especially predators, including the rosy wolf snail from Florida, combined with other environmental perturbations resulted in the extinction of 50-90% of Hawaii’s land snails. Our surveys found 18 extant species of Auriculella about 58% of the known diversity in the genus. One of these species appears to be undescribed and the first member of Oahu’s endemic A. perpusilla group to be found in the Waianae Mountains. We use new anatomical data to compare known species to the new species. Genetic data supports the strong divergence of the new species from A. perpusilla, the only extant species in the A. perpusilla group.