SOLOMONS, Md. — July 29, 2026 – A newly described species of fossil pea crab from Calvert Cliffs has been named in honor of the late Bill Prochownik, a longtime Calvert Marine Museum paleontology volunteer and icon of the local paleontological community who passed away unexpectedly in 2023.
The new species, Pinnotheres prochowniki, is described in a recently published research article in the Journal of Crustacean Biology. The study was a collaborative effort between researchers at the Calvert Marine Museum and Kent State University.
Pea crabs are small and known for living within host animals, such as the shells of live clams, oysters and other similar animals. The newly described fossil crabs date to approximately 10 million years ago, during the Miocene Epoch. Specimens were discovered along Calvert Cliffs in Calvert County, Maryland, and in a similarly aged fossil deposit along the Potomac River in Virginia.
Many of the fossil crabs were preserved inside the shells of their host clam, the surf clam Mactrodesma subponderosa. The clams and crabs were likely rapidly buried in sediment, resulting in exceptional preservation of the crabs. Some of the fossils have delicate soft tissues preserved, including the gills of the crab.
The fossils provide a rare view of interactions between species in an ancient marine ecosystem. Evidence of relationships between species are typically inferred from trace fossils, which record an organism’s behavior rather than preserve the organism itself. In this case, researchers can directly observe that the crabs lived, possibly as a parasite, in these clams, and only these clams.
A similar relationship can be observed today in the Chesapeake Bay. Modern oyster crabs, Zaops ostreum, live inside oysters and are close relatives of the newly described fossil pea crab. Although the two species share a similar way of life, their precise evolutionary relationship remains unclear.
The research article, “Exceptionally Preserved Pea Crabs (Decapoda, Brachyura, Pinnotheroidea) From the Miocene St. Marys Formation, Eastern USA, Exhibiting Preferential Symbiosis With the Surf Clam Mactrodesma subponderosa (Ward, 1992),” was authored by Stephen C. Groff, Victor J. Perez, Carrie E. Schweitzer, John R. Nance, and Cory C. Deltrove.
For a copy of the research article, visit https://academic.oup.com/jcb/article-abstract/doi/10.1093/jcbiol/ruag041/8742033?utm_source=authortollfreelink&utm_campaign=jcb&utm_medium=email
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