60 



Fred C. Rohde, Mary L. Moser and Rudolf G. Arndt 



Rustyside sucker, Thoburnia hamiltoni Raney and Lachner 



The rustyside sucker is endemic to the upper Dan River system in North 

 Carolina and Virginia (Jenkins and Burkhead 1994). In North Carolina it is 

 known only from the 1 .4 rkm downstream-most portion of the Little Dan River 

 in Stokes County. Here Menhinick (1986) collected four specimens at a point 

 some 400 m downriver of the Virginia line in 1985 (Fig. 11). We made three col- 

 lections in the Little Dan River, from its confluence with the Dan River upstream 

 to the North Carolina/Virginia line, and took one adult (144 mm SL) in a run with 

 gravel and rubble substrate on 21 December 1992. In Virginia we took three 

 adults (1 18-142 mm SL) in the Dan River at one site located 365 m, and at anoth- 

 er site 914 m, downriver of the Pinnacles Power Plant on 28 November 1993 

 (Fig. 11). Both sites were deep and fast rock-strewn riffles, current velocity 0.62- 

 0.75 m/sec, water temperature 8.3 C, pH 6.8, and dissolved oxygen concentra- 

 tion 10.0 ppm. The distribution of the rustyside sucker in North Carolina is 

 extremely limited, and its continued existence there is precarious. 



Fig. 11. Distribution of the rustyside sucker, Thoburnia hamiltoni, in the Dan 

 River system, North Carolina and Virginia. 



