Coosa Chub

description

Description. — Characters listed in the diagnosis are not repeated here, unless additional clarification is required. Variation in meristic characters is presented in Table 1. Dorsal-fin rays 8; anal-fin rays 8, rarely 7; pectoral-fin rays usually 14 – 15 (range 12 – 15); pelvic-fin rays usually 8 (range 7 – 9); lateral-line scales usually 36 – 38 (occasionally 39); predorsal scales irregularly distributed and poorly defined, numbering 15 – 17 (rarely 18 or 19); body-circumferential scale rows above and between lateral lines on either side of body 9 to 11 (occasionally 12); body-circumferential scale rows below and between lateral lines on either side of body usually 10 – 12 (range 9 – 13); total caudal-peduncle scale rows uniformly 12 (five rows above and below lateral lines on either side of body); total vertebrae usually 38 (range 37 – 39), these averaging higher (often 39) in upper areas of Coosa River drainage in Georgia and Tennessee; pharyngeal teeth usually 1,4 - 4,1, the lesser tooth occasionally absent from one or both sides of pharyngeal arch; pharyngeal teeth short, thin, and hooked, with little or no grinding surface; anal and dorsal fins bluntly pointed to slightly fa

Morphological and genetic evolution in eastern populations of the Macrhybopsis aestivalis complex (Cypriniformes: Cyprinidae), with the descriptions of four new species

diagnosis

Diagnosis. A species of the Macrhybopsis aestivalis complex, as defined in the generic diagnosis. Distinguished from all other members in the complex in having 1,4 – 4,1 pharyngeal teeth; anal opening situated midway between pelvic and anal-fin origins (vs. 70 percent of distance in all other congeners except Macrhybopsis pallida); origin of dorsal fin situated distinctly posterior to imaginary line extending upward from pelvic-fin origins; belly anterior to pelvic fins usually with a complete bridge of scales (two to five scales deep), the bridge mostly obscured by overlying epidermal tissue about 20 percent of the time. Other important diagnostic features include a single pair of short maxillary barbels; eight anal rays; upper twothirds of body strongly pigmented with relatively large and prominent melanophores, interspersed with smaller melanophores (Fig. 1 C); pectoral fins in both sexes short and moderately to strongly rounded, seldom if ever extending posterior to pelvic-fin origin; snout short and rounded, its length slightly longer than diameter of eye; tubercles on pectoral fins of nuptial males relatively well defined only in first row, those tubercles in subsequent rows

Morphological and genetic evolution in eastern populations of the Macrhybopsis aestivalis complex (Cypriniformes: Cyprinidae), with the descriptions of four new species

discussion

Comments. Macrhybopsis etnieri is one of the most morphologically distinctive members of the M. aestivalis complex (Fig. 1 C), most notably in having a unique pharyngeal-tooth count (usually 1,4 - 4,1), intermediate position of anus relative to pelvic and anal-fin origins, more posterior position of the dorsal fin relative to the pelvic fins, and very small nuptial tubercles on pectoral-fin rays of breeding males. Macrhybopsis etnieri shares, with M. pallida, two characters unique to members of the M. aestivalis complex, namely an intermediate position of the anus relative to the origins of the pelvic and anal fins (versus over twothirds of distance in other species), and well developed genital papillae (versus papillae lacking or extremely reduced). Eisenhour (2004: figs. 16 – 17) hypothesized a close relationship between the two species, presumably based largely on these two characters. Their respective geographic distributions raise doubts as to this proposed relationship, since biogeographically their ranges are quite disjunct and this relationship is not duplicated by any other known closely related pairs of fish species. This hypothesis also is not supported by genetic data p

Morphological and genetic evolution in eastern populations of the Macrhybopsis aestivalis complex (Cypriniformes: Cyprinidae), with the descriptions of four new species

distribution

Distribution. Macrhybopsis etnieri is restricted to upper sections of the Mobile Bay basin, above the Fall Line, including the Cahaba, Coosa and Tallapoosa river systems, in Alabama, northwestern Georgia, and extreme southeastern Tennessee (Fig. 2). It is replaced below the Fall Line by Macrhybopsis boschungi, to which it is not intimately related but with which it occurs sympatrically (or syntopically) in an approximately 40 - km section of the middle Cahaba River system in central Alabama (Fig. 2). More detailed distributional information appears below. Habitat. Macrhybopsis etnieri occurs in clear, moderately large flowing streams with a sand, gravel, or fine rubble bottom above the Fall Line in the Cahaba, Coosa and Tallapoosa river systems of Alabama, Georgia, and Tennessee. Collections are largely concentrated in three areas: the Etowah River (upper Coosa drainage) in northwestern Georgia; Hatchet Creek, in Coosa and Clay counties, Alabama; and the middle Cahaba River south of Birmingham, Alabama. Other collections are known from scattered localities, including the Choccolocco Creek watershed in Cleburne and Talladega counties, Alabama; the Tallapoosa River system of eastern

Morphological and genetic evolution in eastern populations of the Macrhybopsis aestivalis complex (Cypriniformes: Cyprinidae), with the descriptions of four new species