Interior Low Plateau Distributional Patterns 175 



fishes (Table 1), and the Mobile and Escambia drainages share at least 

 seven species: Hybognathus hayi Jordan, Pimephales notatus (Rafin- 

 esque), Notropis baileyi Suttkus and Raney, Etheostoma histrio Jor- 

 dan and Gilbert, E. proeliare (Hay), Percina ouachitae (Jordan and Gil- 

 bert) {-P. uranidea (Jordan and Gilbert)), and Stizostedion vitreum 

 (Mitchill) (Lee et al. 1980; Smith-Vaniz 1968). Many of these species, of 

 course, range over much of the Low Plateau, although some of them are 

 more restricted in distribution and some species have been unable to 

 effect exchange between the river systems. Etheostoma squamiceps Jor- 

 dan, for example, occurs in southern Illinois, western Kentucky, and 

 southwestern Indiana (Wabash drainage in Posey County), and in the 

 Tennessee River system of west-cental Tennessee, Alabama, and Missis- 

 sippi (Page et al. 1976), but has not been reported from the Alabama 

 River system. Many Nothonotus and Catonotus show similar distribu- 

 tional patterns, albeit superimposed upon strong endemicity. 



The Tennessee, Cumberland and Green river systems have received 

 varying contributions to their fish faunas from other systems, and have 

 made contributions to other drainages in the Interior Low Plateau. All 

 have served as piscine speciation centers and as reservoirs for endemic 

 species. One of the sources for Low Plateau fishes was obviously the 

 Lower Mississippi River system, but the species derived from there 

 mostly exhibit marginal or extralimital patterns in the Plateau. Excep- 

 tions are seen in the Green and Tradewater rivers, Kentucky, where they 

 have effected rather wide distribution. Elsewhere, these fishes retain 

 populations in more or less stable, protected, relict habitats, like those 

 reported by Gunning and Lewis (1955) in southwestern Illinois. The 

 species assemblage of that swampine environment includes fishes with 

 mostly southern affinities: Aphredoderus sayanus (Gilliams), common 

 in the Green River; Umbra limi (Kirtland); Fundulus notti (Agassiz); 

 Elassoma zonatum Jordan, historically common in both the Green and 

 Tradewater rivers; Lepomis symmetricus Forbes; Centrarchus macrop- 

 terus (Lacepede), common in the Green River; Etheostoma gracile 

 (Girard), common in the Green River; and Chologaster agassizi Put- 

 nam, not southern but Low Plateau. Umbra limi, which also occurs 

 sporadically along the margin of the Low Plateau (Clay 1975; Sisk 

 1973), is of northern origin. According to Wiley (1977), the Fundulus 

 notti species complex originated in the Lower Mississippi basin and, 

 abetted by stream captures between the Mississippi and the Mobile Bay 

 drainages, spread elsewhere. Fundulus notti barely penetrates south- 

 western Kentucky (Burr 1980) and Tennessee (Baker 1939) outside the 

 Low Plateau. In Tennessee, the only non-embayment record for F. notti 

 is from the Big Sandy River, a system with a host of embayment spe- 

 cies, although the species is widespread in the Obion, Forked Deer and 

 Hatchie rivers (D. Etnier, pers. comm.). 



