Transactions of the Illinois State Academy of Science (2013) Volume 106, pp. 1-2 received 12/12/12 accepted 5/7/13 First Occurrence of the Bankclimber Plectomerus dombeyanus (Valenciennes, 1827) (Mollusca: Unionidae) in Illinois Jeremy S. Tiemann 1 *, Kevin S. Cummings 1 , and John E. Schwegman 2 1 Illinois Natural History Survey, Prairie Research Institute, University of Illinois, 1816 South Oak Street, Champaign, IL 61820 2 2626 Riverpoint Lane, Metropolis, IL 62960 *Correspondence: jtiemann@illinois.edu ABSTRACT Fresh-dead specimens of the freshwater mussel Bankclimber Plectomerus dombeyanus (Valenciennes, 1827) were discovered in the Il- linois portion of the Ohio River near America, Pulaski County, Illinois, at river mile 970 (37.12104N, 89.11468W) during the summer of 2012. he specimens were deposited in the Illinois Natural History Survey Mollusk Collection, Champaign (INHS 42354 and INHS 42977). While reported from elsewhere in the Ohio River basin, these specimens represent the irst time the species has been recorded in Illinois. he Bankclimber Plectomerus dombeyanus (Valenciennes, 1827) is a freshwater mussel (Mollusca: Unionidae) that typically has a thick, rhomboidal shaped, moderately in- lated shell and obtains lengths up to 150- mm (Parmalee and Bogan, 1998; Williams et al., 2008). Its periostracum is greenish brown to brown and darkens to black with age, and its nacre is usually deep purple (Parmalee and Bogan, 1998; Williams et al., 2008). Plectomerus dombeyanus has been described as a “mud-loving” species that “delights in sluggish lowing water” (Call, 1895). he animal inhabits medium to large rivers, oxbow lakes, and lowland ditches, and is found in clay, mud, sand or rocky substrates (Oesch, 1984; Williams et al., 2008). It occurs along channel mar- gins in sluggish to moderate current, but can be found buried in steep slopes a con- siderable distance from the main channel (Oesch, 1984; Williams et al., 2008). Plectomerus dombeyanus is commonly found in Gulf drainage streams from the Alabama River west to eastern Texas, in- cluding the lower Mississippi River to its conluence with the Ohio River (Parmalee and Bogan, 1998; Williams et al., 2008). he species was irst reported from the Ohio River basin in 1981, when two live individuals were discovered in Kentucky Lake, Trigg County, Kentucky (Pharris et al., 1984). Since then, P. dombeyanus has expanded its range throughout the lake (Parmalee and Bogan, 1998; Cicerello and Schuster, 2003), and has been found downstream of the Kentucky Dam in the Tennessee River (JES pers. obs). he Bank- climber also has been collected at three locations in the Kentucky portion of the Ohio River mainstem: 1) in 1982, a relict specimen at river mile 944, near Paducah, McCracken County (Ron Cicerello, Ken- tucky State Nature Preserves Commission, retired, pers. comm.); 2) in 1996, a fresh- dead specimen at river mile 784, which is at its conluence with the Green River, Henderson County (Watters and Myers Flaute, 2010; Ohio State University Divi- sion of Molluscs, Columbus, Bivalve Col- lection #58992), and 3) in 2012, two live individuals at river mile 935 (Heidi Dunn, Ecological Specialists, Inc., pers. comm.). However, the animal has not been listed as part of Illinois’ native mollusk fauna (e.g., Cummings, 1991; Cummings and Mayer, 1992; Cummings and Mayer, 1997; Tiemann et al., 2007) until now. One fresh-dead 48-mm specimen was discov- ered in the Ohio River at river mile 970 (37.12104N, 89.11468W) near America, Pulaski County, Illinois, on 27 June 2012 by JES (Figure 1). Another fresh-dead specimen (44-mm) was recorded from the Figure 1. Bankclimber Plectomerus dombeyanus (INHS 42354) from the Ohio River at river mile 970 (37.12104N, 89.11468W) near America, Pulaski County, Illinois.