Pyganodon grandis

Hoeh (1990) split Anodonta cataracta cataracta and Anodonta cataracta fragilis into distinct species (elevating Pyganodon to genus level in the process). Also Hoeh and Burch (1989) separated Anodonta lacustris as a valid species from Anodonta grandis and Anodonta cataracta and Hoeh (1990) placed them in Pyganodon as Anodonta marginata sensu stricto, is considered a nomen dubium (see Hoeh and Burch, 1989). Zanatta et al. (2007) supported the monophyly of both Pyganodon and Utterbackia using mutation coding of allozyme data, but also resolved the Eurasian Anodonta cygnea to Pyganodon, Utterbackia, and North American Anodonta; indicating further phylogenetic analysis of the Anodontinae is required including both North American and Eurasian species. There is some speculation that this species may hybridize with Pyganodon cataracta (Kat, 1985; 1986). It is undoubtedly a species complex that needs more study throughout its range (Park and Burch, 1995).

This species is widespread and common in North America and can tolerate a much wider range of habitats than many other unionids.

This species is commonly distributed throughout Canada and the U.S. in the Mississippi, Great Lakes, and Hudson Bay basins. It also occurs in the Gulf of Mexico drainage area of Louisiana and Texas, and in the Red River drainage in Texas and Oklahoma. It has been introduced to some areas as glochidia on stocked fish hosts (Upper Lake Mary, Arizona- Hovingh, 2004; tidal Hudson River in Haverstraw, New York- Mills et al., 1996). In the Apalachicola Basin (ACF basin = formed by Apalachicola, Chattahoochee, and Flint Rivers) of Alabama, Florida, and Georgia, this species is historically known from 59 records from 29 sites and was considered widespread throughout the ACF system including the main channel and tributaries of the Apalachicola, Chipola, Chattahoochee, and Flint Rivers (Brim Box and Williams, 2000).

It is common in all Illinois drainages (Cummings and Mayer, 1997; Schanzle and Cummings, 1991; Schanzle et al., 2004; Sietman et al., 2001; Tiemann et al., 2005). Indiana: lower E Fork White (Harmon, 1992), Tippecanoe (Cummings and Berlocher, 1990); Muscatatuck (Harmon, 1989); Eel, St. Mary's, St. Joseph, Maumee (Pryor, 2005); and all of Ohio (Watters, 1995; Lyons et al., 2007; Hoggarth et al. 2007; Watters et al., 2009). In West Virginia, it occured in the Upper Ohio/Kanawha (Zeto et al., 1987) and Mud River (Guyandotte drainage) (Schmidt and Zeto, 1986). It is in every Minnesota drainage (Sietman, 2003): Lake of the Woods, Lake Superior Red (Graf, 1997; Cvancara, 1970). In Texas, it is in all drainages (Howells et al., 1996) introduced in Clement Lake, El Paso Co. and lower Rio Grande (Johnson, 1999). It is common throughout Alabama (Mirarchi, 2004); Choctawhatchee (Blalock-Herod et al., 2005), Alabama (McGregor et al., 1999); Florida in the Escambia (Butler, 1989) and Bear Creek, AL/MS (McGregor and Garner, 2004); not Yellow, Blackwater, and Perdido (Williams et al., 2008). Once since 1990s from Conecuh-Escambia and Choctawhatchee (Pilarczyk et al., 2006). In the Coosa basin, Georgia, it is historical from the Coosa, Etowah, Oostanaula, Conasauga, and Coosawattee (Williams and Hughes, 1998). It is in South Dakota streams (Backlund, 2000); incl. Lakes Lewis and Clark, Oahe and Sharpe, James (Perkins and Backlund, 2003), Big Sioux (Skadsen and Perkins, 2000), Minnesota River basins (Shearer et al., 2005). In Montana, it is in the NE and SE (Milk, Missouri, Little Missouri, Yellowstone, Musselshell drainages) (Gangloff and Gustafson, 2000; Stagliano, 2010). In Vermont, it is only in Lake Champlain and tribs- Missisquoi, Lamoille, Otter, East, Hubbardton, Poultney, Winooski Rivers (Fichtel and Smith, 1995). In Wisconsin it is widespread and abundant (Mathiak, 1979). In North Carolina, it is in the French Broad River and introduced in Jordan Lake (Cape Fear basin) (Bogan, 2002). In Mississippi, it is in all drainages except Coastal (Jones et al., 2005); Strong River (Darden et al., 2002). In Louisiana, it is common and widespread (Vidrine, 1993). Arkansas: Poteau (Vaughn and Spooner, 2004), Ouachita (Posey et al., 1996), Cache (Christian, 1995; Christian et al., 2005), White (Gordon, 1982; Gordon et al., 1994), St. Francis (Ahlstedt and Jenkinson, 1991), lower Arkansas (Gordon, 1985). In Tennessee, it is in the upper Powell, Clinch, Elk, Harpeth, Duck, Obion, Hatchie; impounded Tennessee and Cumberland Rivers, and Reelfoot Lake (Parmalee and Bogan, 1998). It is in the ACF basin (AL/FL/GA) (Brim-Box and Williams, 2000). In Kentucky, it is nearly statewide (Cicerello and Schuster, 2003; Gordon, 1991). In Wyoming, it is in the Belle Fourche and Little Missouri drainages, Cooke Co. (Cvancara, 2005). In Colorado, it is stable on eastern plains but lentic (Cordeiro, 1999; Wu, 1989; Clark et al., 2003). Oklahoma: Chikaskia, Verdigris, Kiamichi, Poteau, Neosho, Glover, Little, Mountain Fork, Blue, Washita, Red Rivers; Lake Murray, Texoma, Big and Middle Caney rivers (Branson, 1983; Vaughn, 2000). In Kansas, it is statewide and common (Couch, 1997; Tiemann, 2006). It is in the Little Blue basin (Hoke, 2004); and common in the Big Blue system, SE Nebraska and NE Kansas (Hoke, 2005) and common in Platte (Freeman and Perkins, 1992) and Cherry Co. on Niobrara (Freeman and Perkins, 1997) Rivers, Nebraska. It is in the Clinton drainage, Michigan (Trdan and Hoeh, 1993; Strayer, 1980) to Kalamazoo River (Mulcrone and Mehlne, 2001) to upper peninsula (Goodrich and Van der Schalie, 1939) in Lakes Michigan, Huron, St. Clair (Badra and Goforth, 2003). In Canada, it is widespread and common from Alberta and Northwest Territories (N to Shell Lake, Inuvik) E through Manitoba (Assiniboine drainage- Watson, 2000; Pip, 2006) to Ontario (Metcalfe-Smith et al., 2003; Schueler and Karstad, 2007) and Quebec (Metcalfe-Smith and Cudmore-Vokey, 2004).

Is tolerant of low oxygen levels and conditions in some impounded areas. Gross water pollution would probably be fatal. This species is also tolerant of flow regime change and can survive sedimentation and pollution events.