Share your observations

Share your observations of plants or non-game animals with the Natural Heritage Inventory

Rare animals
Find rare and non-game animals.
Rare plants
Learn about plants on the Natural Heritage Working List.
Rare lichens
Discover Wisconsin's lichens.
Natural communities
Explore Wisconsin's natural communities.
Other features
Discover unique resources.
Eagle license plate

Help care for rare plants and animals by ordering an Endangered Resources plate.

Contact information
For information on Wisconsin's rare vertebrate animals, contact:
Rich Staffen
Conservation Biologist
For information on Wisconsin's rare invertebrates, contact:
Jay Watson
Conservation Biologist

Rock Pocketbook (Arcidens confragosus)



Rock Pocketbook (Arcidens confragosus), listed as Threatened in Wisconsin, is found in large rivers in the western part of the state. It is found in all substrate types where there is current. Five fish species have been recorded as its host including eel, drum, shad, rockbass, and crappie.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Rock Pocketbook (Arcidens confragosus). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.

Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.

Documented locations of Arcidens confragosus in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusTHR
Federal Status in Wisconsinnone
State RankS1S2
Global RankG4
Tracked by NHIY

Species guidance

Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).

Identification: Shell is thin to moderately thick and inflated. Umbos are elevated and located near the middle of the shell. Sculpturing consists of two rows of knobs that continue onto the posterior part of the shell and form into folds. The outside of the shell is olive-green to green. Larger shells become black, thicken and may lose the crinkly appearance, while the younger, smaller shells are greenish. Pseudocardinal teeth are narrow and elongated, while lateral teeth are indistinct. Nacre is white and iridescent posteriorly. Length to 7 inches (17.8 cm).

Habitat: Most often found in sluggish water at shallow depths of less than one meter on a firm mud bottom. Inhabitants of quiet pools on a mud or stable sand bottom.

State Distribution: Occurs in the Mississippi River and the lower Wisconsin River.

Phenology: The species is a winter breeder. Glochidia are present in the latter part of January and embryos in the middle of March. Host fish are known to be freshwater drum (Aplodinotus grunniens), American eel (Anguilla rostrata), gizzard shad (Dorosoma cepedianum), rock bass (Ambloplites rupestris), and white crappie (Pomoxis annularis). Breeding occurs from September to June.

Management Guidelines: Habitat destruction and river pollution have resulted in mussel declines. Protection of habitat and improvements in water quality along with restriction of dredging, impoundments, sand and gravel mining, and navigational improvements would benefit this species.



Rock Pocketbook

Photo ©  Illinois Natural History Survey.

Wildlife Action Plan

Wisconsin Wildlife Action Plan graphic

Natural community (habitat) associations

The table below lists the natural communities that are associated with Rock Pocketbook. Only natural communities for which Rock Pocketbook is "high" (score=3) or "moderate" (score=2) associated are shown. See the key to association scores for complete definitions. Please see the Wildlife Action Plan to learn how this information was developed.

Natural community Score
Warmwater rivers 3

Ecological landscape associations

The table below lists the ecological landscape association scores for Rock Pocketbook. The scores correspond to the map (3=High, 2=Moderate, 1=Low, 0=None). For more information, please see the Wildlife Action Plan.

This map shows the probability of Rock Pocketbook occurring in each of Wisconsin's Ecological Landscapes.  Actual scores can be found in the table to the left.

Ecological landscape score
Western Coulee and Ridges 3
Western Prairie 2

Back to Top

Landscape-Community combinations of highest ecological priority*

Ecological priorities are the combinations of natural communities and ecological landscapes that provide Wisconsin's best opportunities to conserve important habitats for a given Species of Greatest Conservation Need. The 10 highest scoring combinations are considered ecological priorities and are listed below. More than 10 combinations are listed if multiple combinations tied for 10th place. For more information, please see the Wildlife Action Plan.

* Ecological priority score is a relative measure that is not meant for comparison between species. This score does not consider socio-economical factors that may dictate protection and/or management priorities differently than those determined solely by ecological analysis. Further, a low ecological priority score does not imply that management or preservation should not occur on a site if there are important reasons for doing so locally.

Back to Top

Issues/threats and conservation actions

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Threats/issues and conservations actions for rare animals

Back to Top

Last revised: Thursday, December 22, 2022