The Madison Cave isopod (Antrolana lira) is protected under the Endangered Species Act (ESA) since reproduction and genetic diversity are very low, and it exists in only seven sites that are isolated from each other. The species is a 15-18 mm (~two thirds of an inch) long colorless relative of crabs, lobsters, and pill bugs. There are 2-3 times more females than males in the population, though few have been observed to lay eggs. Little is known about the life cycle, especially since young isopods are rare. Because of the low population growth of this species even in ideal conditions, it is crucial to protect the quality of their remaining limited freshwater cave habitat.
Madison Cave isopod back view
Madison Cave isopod facing left
Madison Cave isopod facing right
Madison Cave isopod belly
Back, side, and belly views of the Madison Cave isopod.
Protecting Madison Cave Isopod Habitat
The Madison Cave isopod is found in 52-57°F flooded limestone caves beneath the Great Valley of Virginia and West Virginia, where it swims freely through freshwater aquifers. There are seven documented population centers in Augusta County, VA, Rockingham County, VA, and the valley of the main stem of the Shenandoah River (Warren and Clarke counties, VA, and Jefferson County, WV). Madison Saltpetre Cave was the first documented location, so the species is named for that cave even though populations exist in six more sites elsewhere.
Photo of a cave with reflective water
Photo of a cave with reflective water
Photo of a cave with reflective water
Pesticides as a Concern
The Madison Cave isopod is struggling to reproduce even when cave water habitat is untouched by outside chemicals, so pesticides that contaminate the groundwater or reach the cave aquifer habitat may cause additional problems. Very little is known about the biology of this species, which puts it in a delicate position.
Pesticide Use Limitation Area(s) Coming Soon!
For the vulnerable species, EPA plans to require any necessary additional mitigations only in geographically specific areas (referred to as Pesticide Use Limitation Areas or PULAs), unless the mitigations that are already required on a label are sufficient to address potential impacts. EPA is currently developing refined maps that EPA plans to use for PULAs. EPA does not plan to implement the VSAP for a particular vulnerable species prior to refining its map, which will likely be later in 2024.
Other Species that May Benefit
Potential mitigation for the Madison Cave isopod may benefit other aquatic and sensitive cave species directly found within the Madison Cave isopod range, and there may also be indirect benefits for terrestrial species. Any potential mitigation would target groundwater and therefore provide benefits for aquifer use.
Left to right: Tricolored bat (Perimyotis subflavus), Virginia big-eared bat (Plecotus townsendii), Indiana bat (Myotis sodalis), Northern Long-eared bat (Myotis septentrionalis)
Photo of Candy Darter fish
Photo of Eastern Prairie Fringed Orchid
Photo of Harperella plant
Photo of Virginia sneezeweed
Photo of Rufa Red Knot bird
Photo of Northeastern bulrush plant
Photo of Small whorled pogonia plant
Photo of Swamp Pink plant
Top: Candy darter (Etheostoma osburi) Center left to right: Eastern Prairie Fringed Orchid (Platanthera leucophaea), Harperella (Ptilimnium nodosum), Virginia sneezeweed (Helenium virginicum), Rufa Red Knot (Calidris canutus rufa). Bottom left to right: Northeastern bulrush (Scirpus ancistrochaetus), Small whorled pogonia (Isotria medeoloides), Swamp Pink (Helonias bullata).
Link to Species Profile
The FWS species profile page on the Environmental Conservation Online System contains a lot of useful information about the Madison Cave isopod, like where the species is located, the recovery plans for the species, and 5-year status reviews.
