Key to species of Macrhybopsis aestivalis complex east of Mississippi River

1a. Anal-fin rays usually 7; two pairs of maxillary barbels; dorsal-fin origin directly above pelvic-fin origin; pharyngeal teeth always 4-4; anal opening midway between pelvic and anal-fin origins; body essentially pallid, the melanophores tiny and usually not readily visible; belly scaleless anterior to pelvic fins; pectoral-fin rays in males long and pointed, the outer rays notably longer than innermost rays (fins generally shorter in females) and often extending past pelvic-fin origin; average body size smaller, rarely reaching 50 mm SL, with great majority of specimens (all but six of 667 specimens examined) under 46 mm SL................................................................................... Macrhybopsis pallida Eastern Gulf slope drainages of western Florida and southeastern Alabama, including Escambia, Blackwater Bay, and Choctawhatchee river drainages

1b. Anal-fin rays usually 8; one pair of maxillary barbels; dorsal-fin origin either directly above or distinctly behind pelvic-fin origin; pharyngeal teeth either 4-4, 1,4-4,1, or some combination thereof; anal opening either midway between pelvic and anal-fin origins or distinctly closer to anal-fin origin; body pigmentation variable, the body rarely if ever pallid and melanophores normally prominent and readily visible; belly squamation variable, ranging from scaleless to an obvious bridge of scales across belly immediately anterior to pelvic-fin origin; pectoral fins in males variable in length (fins generally shorter in females), the outermost rays sometimes distinctly longer than inner rays and the fins more pointed and reaching pelvic-fin origin, at other times the outer rays not notably longer and the fin rounded, falling well short of pelvic-fin origin; average body size larger, occasionally reaching 60 mm SL and often exceeding 50 mm SL................................................2

2a. Anal opening midway between origins of pelvic and anal fins; number of scale rows above and between lateral lines on either side of body usually 9 or 10, rarely 11; pharyngeal teeth usually 1,4-4,1, occasionally with tooth absent from one or (very rarely) both lesser rows; dorsal-fin origin distinctly posterior to hypothetical vertical line extending upward from pelvic-fin origin (Fig. 1 C); belly immediately anterior to pelvic fins usually heavily scaled and forming a bridge of two to five scales across belly; body pigmentation comprising a combination of numerous large and small melanophores, these often coalesced along mid-side of body to form a poorly defined lateral stripe; pectoral fins short and broadly rounded at tip, seldom if ever extending posteriorly to pelvic-fin origin; snout shorter and blunter, the preorbital length either less, or equal to, postorbital length; total vertebrae usually 38 or 39 (counts averaging higher in headwater areas of Georgia and Tennessee)................................................................................................ Macrhybopsis etnieri Mobile Bay basin; restricted to areas above Fall Line in Cahaba, Tallapoosa and Coosa river systems in Alabama, Georgia and Tennessee; occurs sympatrically with Macrhybopsis boschungi (with no evidence of hybridization) over a 40-km section of middle Cahaba River in Fall Line region of Alabama