Pyganodon grandis

{{Short description|Species of bivalve}} {{Inline|date=January 2023}} {{Speciesbox | image = Naturalis Biodiversity Center - RMNH.MOL.326382 - Pyganodon grandis (Say, 1829) - Unionidae - Mollusc shell.jpeg | genus = Pyganodon | species = grandis | status = LC | status_system = IUCN3.1 | status_ref = <ref>{{cite iucn|author1=Cummings, K.|author2=Cordeiro, J.|year=2012|title=''Pyganodon grandis''|article-number=e.T189102A1919024|doi=10.2305/IUCN.UK.2012-1.RLTS.T189102A1919024.en|access-date=8 June 2023}}</ref> | status2 = G5 | status2_system = TNC | status2_ref = <ref name=NS>{{cite NatureServe |id=2.117497 |title=''Pyganodon grandis'' |access-date=30 December 2025}}</ref> | authority = ([[Thomas Say|Say]], 1829) | synonyms = {{Collapsible list|bullets=yes|''Anodonta grandis'' Say, 1829|''Anodonta grandis'' subsp. ''grandis'' Say, 1829|''Anodonta grandis'' subsp. ''simpsoniana'' Lea, 1861|''Anodonta grandis'' subsp. ''corpulenta'' Cooper, 1834|''Anodonta lugubris'' Say, 1829|''Anodonta inflata'' Rafinesque, 1831|''Anodonta stewartiana'' Lea, 1834|''Symphynota benedictensis'' Lea, 1834|''Anodonta corpulenta'' Cooper, 1834|''Anodonta plana'' Lea, 1834|''Anodonta declivis'' Conrad, 1834|''Anodonta gigantea'' Lea, 1838|''Anodonta ovata'' Lea, 1838|''Anodonta salmonia'' Lea, 1838|''Anodonta decora'' Lea, 1838|''Anodonta pepinianus'' Lea, 1838|''Anodonta harpethensis'' Lea, 1840|''Anodonta footiana'' Lea, 1840|''Anodonta maryattana'' Lea, 1840|''Anodonta globosa'' Lea, 1841|''Anodonta virens'' Lea, 1852|''Anodonta linnaeana'' Lea, 1852|''Anodonta opaca'' Lea, 1852|''Anodonta lewisii'' Lea, 1857|''Anodonta danielsii'' Lea, 1858|''Anodonta gesnerii'' Lea, 1858|''Anodonta texasensis'' Lea, 1859|''Anodonta kennicottii'' Lea, 1861|''Anodonta simpsoniana'' Lea, 1861|''Anodonta leonensis'' Lea, 1862|''Anodonta dallasiana'' Lea, 1863|''Anodonta bealei'' Lea, 1863|''Anodon subangulata'' J.G. Anthony, 1865|''Anodon subinflata'' J.G. Anthony, 1865|''Anodon imbricata'' J.G. Anthony, 1865|''Anodon micans'' J.G. Anthony, 1865|''Anodon opalina'' J.G. Anthony, 1865|''Anodon mcnielii'' J.G. Anthony, 1866|''Anodon subgibbosa'' J.G. Anthony, 1866|''Anodon inornata'' J.G. Anthony, 1866|''Anodon nopalatensis'' Sowerby, 1867|''Margaron benedictii'' Lea, 1870|''Anodonta sulcata'' Küster, 1873|''Anodonta somersii'' Call, 1880|''Anodonta houghtonensis'' Currier in DeCamp, 1881|''Anodonta grijalvae'' Morelet, 1884|''Anodonta tabascensis'' Morelet, 1884|''Anodonta dakota'' Frierson, 1910|''Anodonta dakotana'' Utterback, 1915|''Anodonta inflata'' subsp. ''viridis'' Rafinesque, 1831|''Anodonta inflata'' subsp. ''fuscata'' Rafinesque, 1831|''Anodonta inflata'' subsp. ''zonalis'' Rafinesque, 1831}} |synonyms_ref=<ref>{{ITIS|id=568179|taxon=''Pyganodon grandis'' (Say, 1829)|access-date=8 June 2023}}</ref> }} {{Commons category|Pyganodon grandis}}

'''''Pyganodon grandis''''', or the '''giant floater''', is a [[species]] of [[freshwater mussel]], an [[aquatic animal|aquatic]] [[bivalve]] [[mollusk]] in the family [[Unionidae]], the river mussels. This species is fast-growing, large, and has a short lifespan. It is variable and widespread<ref>{{Cite web |title=MUSSELp {{!}} Mussel of the Month |url=https://mussel-project.uwsp.edu/motm/2007/07-09.html |access-date=2023-08-03 |website=mussel-project.uwsp.edu}}</ref> across the [[United States]] and southeastern [[Canada]].

Original description (Say 1829): "Shell very large, subovate; disk unequally wrinkled and undulated transversely, dark yellowish brown; umbo elevated; beak slightly elevated, with generally, two or three small sinuous, acute undulations; hinge margin slightly arquated, sometimes nearly rectilinear, somewhat angulated at its anterior termination, thence the edge descends by a nearly rectilinear, or slightly concave line to the anterior margin, which is considerably narrowed; sinus of the hinge margin concave; posterior margin widely rounded; within white margined, particularly before, with dusky."

==References== {{reflist}} * Binney, W.G. 1858. The complete writings of Thomas Say on the conchology of the United States. Bailliere Publ. NY * Haag, W. R. (2012). ''North American Freshwater Mussels: Natural History, Ecology, and Conservation''. Cambridge University Press. {{ISBN|978-0521199384}} * Say, T. 1829. Descriptions of some new terrestrial and fluviatile shells of North America. New Harmony Disseminator of Useful Knowledge, New Harmony, Indiana. (see the description also in Binney's summary of Say's writing, 1858). {{PD-notice}} {{Taxonbar|from=Q3795937}}

[[Category:Molluscs of Canada]] [[Category:Molluscs of the United States]] [[Category:Pyganodon|grandis]] [[Category:Bivalves described in 1829]]