''Quadrula'' is a genus of

freshwater mussel Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails. The majority of bivalve molluscs are saltwater species that l ...

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s in the family

Unionidae The Unionidae are a Family (biology), family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is a ...

native to rivers of the

American Midwest The Midwestern United States (also referred to as the Midwest, the Heartland or the American Midwest) is one of the four List of regions of the United States, census regions defined by the United States Census Bureau. It occupies the northern c ...

and mid-south. All have thick

nacreous Nacre ( , ), also known as mother-of-pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is ...

shells with well-developed

hinge teeth Hinge teeth are part of the anatomical structure of the inner surface of a bivalve shell, i.e. the shell of a bivalve mollusk. Bivalves by definition have two valves, which are joined together by a strong and flexible ligament situated on the hin ...

, many also with external shell sculpturing of nodules or lumps.

Species within the genus ''Quadrula''

In 2012, many species classified as ''Quadrula'' were moved to ''

Rotundaria ''Rotundaria'' is a genus of freshwater mussels, Aquatic animal, aquatic bivalve mollusks in the family Unionidae, the river mussels. Species Species within this genus include: * ''Rotundaria asperata'' (I. Lea, 1861) * ''Rotundaria aurea'' (I. ...

'' and '' Theliderma'' based on genetic and morphological evidence. Species currently in ''Quadrula'' now consist of:''Quadrula'' World Register of Marine Species
/ref> * '' Quadrula apiculata'' (Southern mapleleaf) * '' Quadrula fragosa'' (Winged mapleleaf) * '' Quadrula nobilis'' (Gulf mapleleaf) * '' Quadrula quadrula'' (Mapleleaf) * '' Quadrula rumphiana'' (Ridged mapleleaf) * '' Quadrula verrucosa'' (Pistolgrip)

References

Bivalve genera Molluscs of the United States Taxonomy articles created by Polbot {{Unionidae-stub