7017

• UCREFRP Catalog Number: 7017
• Author: Starnes, W. C.
• Title: Colorado River Basin
• USFW Year: 1989.
• Copyright Material: NO

G. elegans and G. robusta from Green River. Also analyzes
sexual dimorphism, tuberculation, and shape variation and
concludes that hump development is highly variable
character, even in the Grand Canyon area chub population
which they felt to consist purely of cypha.
1979. Smith, G.R., R.R. Miller, and W.D. Sable. Species
relationships among fishes of the genus Gila in the upper
Colorado River drainage. U.S. Nat. Park Serv. Tran. Proc.
Ser. 5:613-623.
Presents a study based primarily on large river (specific
localities not given) Gila specimens (excepting few_
specimens of seminuda from Virgin R.) subjected to principal
components analysis. Points out weaknesses in previous
mathematical analyses of the group, such as that of Holden
and Stalnaker (1970), and how, with the greater
discriminating powers of PCA, that very few "intermediates"
between G. cypha and G. eleaans were found (at least in
specimens obtained from "unmodified" habitats) with robusta
exhibiting essentially complete morphological separation,
except for specimens representing G. K. seminuda. With this
established, attempts are made to develop characters to
distinguish the respective forms by other means to
facilitate management of the species. Concludes that main
Colorado chubs are morphologically segregated and behaving
as reproductively isolated species. The allopatric small
river form,G. r. seminuda, exhibits some morphological
intermediacy between robusta and cypha based on this type of
analysis and San Juan River system specimens examined seemed
to fall into this group as well. In recognizing mainstream
populations as three distinct species, these authors invoked
the "Gila robusta superspecies" concept to comprise these
forms, speculating that eleaans and cypha may have been
derived from robusta in separate speciation events, and also
comprising peripheral forms, such as seminuda, Gila River
basin and Mexican forms. Ambiguous speculation on the
status of intermedia postulates possible allignments with
the robusta complex or with other lineages.
1980. Holden, P.B. Gila elegans; p. 167, in: D.S. Lee et al.,
Atlas of North American Freshwater Fishes. Nor. Car. St.
Mus., Raleigh, -U.S. Fish & Wldlf. Serv. 854 p.
Offers primarily distributional information but includes a
brief summary of taxonomic history.
1980. Holden, P.B., and W.L. Minckley. Gila cypha; p. 165, in:
D.S. Lee et al., Atlas of North American freshwater fishes.
N.C. St. Museum-U.S. Fish & Wildlife Ser. Pub. 854 p.
Offers primarily distributional information but includes a
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