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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

Winged Mapleleaf (Quadrula fragosa)



Winged Mapleleaf (Quadrula fragosa), listed as State and Federally Endangered, is found in large and medium-sized rivers in the Mississippi River drainage, is areas with mixed gravel and sand in riffles or fast-flowing water. It is very rare wherever it is found. The known host fishes are blue and channel catfish.

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 Winged Mapleleaf (Quadrula fragosa). 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 Quadrula fragosa in the Natural Heritage Inventory Database as of July 2015.
Summary Information
State StatusEND
Federal Status in WisconsinLE
State RankS1
Global RankG1
Tracked by NHIY

Species guidance

Winged Mapleleaf (Quadrula fragosa) has very few known occurrences in the state and is of the highest priority for conservation; we encourage you to consult with your District Ecologist or an NHI Zoologist for specific recommendations for your site.

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 square, thick, and yellowish-green to light brown with faint rays in smaller shells, becoming greenish-brown or dark brown in larger individuals. A pronounced wing is present posterior to the umbo with radiating rows of ridges. The beak sculpture has two rows of raised nodules that continue down the surface of the shell separated by a furrow. Anterior and posterior ends are squared or truncated. Pseudocardinal teeth are well developed and serrated. Laterals are long. Striated, and straight. The nacre is pearly white, iridescent posteriorly, Up to 4 inches (10.2 cm) long.

Habitat: Occurs in large rivers on a mixed sand and gravel bottom in water two meters or more in depth.

State Distribution: Occurs only in the St. Croix River.

Phenology: The host fish for this species are likely catfish, although this has yet to be proven. Gravid mussels have been found late September to early October.

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. The development of fish runways to facilitate the movement of host species through or around dams could also help to protect the winged mapleleaf. The U.S. Fish and Wildlife Service has developed a recovery plan for this species.



Winged Mapleleaf

The winged mapleleaf, globally imperiled, is listed as Endangered by both state and federal governments. A significant population of this species inhabits the Lower St. Croix River.

Photo by Lisie Kitchell, WDNR.

Wildlife Action Plan

Wisconsin Wildlife Action Plan graphic

Natural community (habitat) associations

The table below lists the natural communities that are associated with Winged Mapleleaf. Only natural communities for which Winged Mapleleaf 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 Winged Mapleleaf. 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 Winged Mapleleaf occurring in each of Wisconsin's Ecological Landscapes.  Actual scores can be found in the table to the left.

Ecological landscape score
Forest Transition 2
Western Prairie 2
Central Sand Plains 1

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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.

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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

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Last revised: Thursday, October 08, 2020