The Lilliput (Toxolasma parvum) (Mollusca: Bivalvia: Unionidae) Introduced into North Carolina

The native freshwater unionid fauna of the Atlantic Slope Rivers of North Carolina is reported to contain 44 species. There is a single native species of Toxolasma found in North Carolina, the Savannah Lilliput, Toxolasma pullus. Savannah Lilliput occurs from the Altamaha River basin, Georgia, north to the Tar River basin, North Carolina (Johnson 1970; Shelley 1987). Range of the Savannah Lilliput in North Carolina includes the Pee Dee, Waccamaw, Cape Fear, Neuse and Tar River basins (Johnson 1967; Fuller 1977; Porter and Horn 1980; Shelley 1987; Adams et al. 1990; Bogan 2002). There are no records of native Atlantic Slope Toxolasma species north of the Tar River basin (Johnson 1970). Native range of the Lilliput (Toxolasma parvum) is restricted to the Mississippi River basin from Minnesota to southern Louisiana and Texas, from the headwaters of the Ohio in western Pennsylvania, west to the Missouri River drainage of South Dakota and Kansas and tributaries to Lake Erie and Lake Michigan (Williams et al. 2008; Watters et al. 2009). Toxolasma parvum apparently has been introduced outside of its natural range which may be facilitated by the species being hermaphroditic (William et al. 2008). It has been found introduced into New Jersey [NCSM 30076]. The first specimen of Toxolasma parvum from North Carolina was collected in January 2007 from Upper Barton Creek arm of Falls Lake, a reservoir on the Neuse River in Wake County, North Carolina by J. Mays, (NCDOT) [NCSM 46768] and again in December 2007 [NCSM 46807]. R.B. Nichols (NCWRC) collected two specimens near Mays’ locality in December 2007 [NCSM 46688]. A.E. and C.M. Bogan (NCSM) collected additional dead shell specimens from the same area in January 2008 [NCSM 45580, 45585]. J. Mays (NCDOT) collected another pair of valves in October 2009 from Falls Lake Reservoir upstream of the Upper Barton Creek Embayment [NCSM 47151]. Two live specimens were collected and preserved in 100% ethyl alcohol for DNA studies in May 2010 by S.E. McRae, R.A. Harrington, R. Greiner, C.B. Eads, T. Augspurger, R.B. Nichols and J. Mays again from near the boat ramp on Upper Barton Creek Embayment of Falls Lake Reservoir [NCSM 47146]. Initial identification of Toxolasma parvum shells, collected from Falls Lake, was based on presence of a straight ventral margin, shell thinner than T. pullus and no marked sexual dimorphism in these specimens. Toxolasma parvum shells were more elongate and were not as inflated as T. pullus. A small mantle snip was taken from each of the two NCSM 47146 specimens to be used for DNA analyses. DNA was extracted and a portion of the mitochondrial gene cytochrome oxidase subunit 1 [COI] was sequenced following protocols outlined in Raley et al. (2006). These two mtDNA sequences represent a single haplotype and it was accessioned in GenBank as HQ612178. A BLAST search (Zhang et al. 2000) was performed with these sequences which identified them as Toxolasma parvum. These same sequences were inserted into our data matrix of amblemine bivalves where it clustered with another specimen of Toxolasma parvum from Campbell et al. (2005). Morphological characters and the genetic data are sufficient to confirm the identity of these samples as T. parvum. Herein, we confirm the first record of an introduced and established population of T. parvum in North Carolina.