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Provides a taxonomic history of Colorado River basin Gila <br />spp. exclusive of intermedia and its synonyms. Analyzes by <br />j means of taximetrics (an early numerical taxonomy technique) <br />Gila material from widely scattered localities in the <br />Colorado drainage but with heaviest representation from the <br />upper basin. Concluded based on this analysis that robusta <br />and elegans were highly distinct entities morphologically, <br />as well as probably ecologically, and reaccorded specific <br />status to the latter. Concluded rather that the real <br />problems exist between G. eleg_ans and G. cypha with <br />intermediate forms common in some areas for which the term <br />"intergrades" was used, although these were speculated to be <br />hybrids, terms which have opposite taxonomic implications. <br />Also speculated that this situation may have arisen as a <br />result of incomplete speciation followed by introgressive <br />hybridization, perhaps due to habitat alteration in some <br />areas, but not thusly attributable in other areas (e.g, <br />preimpoundment upper Green R.). Pointed out the need for <br />further study of this "intergrading complex" which remains <br />the case today. They also noted that the name G. robusta <br />seminuda should be restricted to populations in the Virgin <br />River pending further study and regarded similarly scaled <br />forms from the upper Colorado basin as phenotypic variants <br />as previously held by Ellis (1914). <br />1970. Rinne, J.N., and W.L. Minckley. Native Arizona fishes: <br />Part III "Chubs". Ariz. Wildlf. Views 17(5):12-19. <br />A popular article which however gives a good account of all <br />species occurring in Arizona, including all pertinent to this <br />study, and good illustrations of each form, as well as <br />detailed range maps for occurrence in Arizona. Accords <br />species status to intermedia and regards robusta as <br />comprising three subspecies (robusta, grahami, seminuda). <br />1971. Minckley, W.L. Keys to native and introduced fishes of <br />Arizona. Proc. Ariz. Acad. Sci. 6:183-188. <br />Provides a detailed key for distinguishing Arizona fish <br />species including Gila spp. intermedia, cypha, elegans, and <br />robusta. <br />1973. Minckley, W.L. Fishes of Arizona. Ariz. Game & Fish <br />Dept., Phoenix. 293 p. <br />Provides a detailed key for distinguishing species listed in <br />the previous reference plus subspecific forms of G. robusta <br />(robusta, seminuda [Virgin R.], and grahami [certain Gila R. <br />tribs.]. Provides complete synonymies and brief <br />descriptions of each species and discusses possible <br />subspecies origins, speculating that grahami represents an <br />9