9420

• UCREFRP Catalog Number: 9420
• Author: Maddux, H. R., J. A. Mizzi, S. J. Werdon and L. A. Fitzpatrick.
• Title: Overview of the Proposed Critical Habitat for the Endangered and Threatened fishes of the Virgin River Basin.
• USFW Year: 1995.
• USFW - Doc Type: Salt Lake City.
• Copyright Material: NO

Muddy River, Nevada, in the late 1960's (Deacon and Bradley 1972), but none have been
collected there since.
Virgin River Chub
The Virgin River chub was described as a full species (Gila seminude) in 1875 (Cope and
Yarrow 1875) and was believed to be restricted to the Virgin River between Hurricane,
Utah, and its confluence with the Colorado River (Figure 1). However, Ellis (1914)
considered this chub to be intermediate between the roundtail chub (G. robusta) and the
bonytail chub (G. elegans), and reduced the Virgin River chub to a subspecies of roundtail
chub (G. robusta seminude).
Until recently, the Service and other authorities (Holden and Stalnaker 1970, Minckley 1973,
Smith et al. 1977) have treated the chub in the Muddy River, as a separate, unnamed
subspecies of roundtail chub (Moapa roundtail chub, G. robusta ssp.). The Service has
considered this chub to be a category 2 candidate for Federal listing since 1982 (47 FR
58455, 54 FR 556, 56 FR 58804).
In a recent taxonomic study of the genus Gila using morphometric and genetic characters,
DeMarais et al. (1992) asserted that full species status (G. seminude) was warranted for
Virgin River chub, the chub in the Muddy River be included within G. seminude, but
considered a distinct form, and G. seminude likely arose through hybridization involving G.
robusta and G. elegans. These taxonomic revisions were accepted by the American Fisheries
Society and the American Society of Ichthyologists and Herpetologists Fish Names
Committee (Mr. Joseph S. Nelson, in lift. 1993). This designation of critical habitat does
not include the Muddy River form of the Virgin River chub because it is not listed under the
Act.
The Virgin River chub was first collected from the Virgin River near Washington, Utah, in
the 1870's by members of the Wheeler Survey. The Virgin River population of the chub
historically was collected within the mainstem Virgin River from Pah Tempe Springs, Utah,
downstream to the confluence with the Colorado River in Nevada (Cope and Yarrow 1875,
Cross 1975). It is likely that Virgin River chub historically occurred well above Pah Tempe
Springs. At present, the Virgin River population of the chub occurs within the mainstem
Virgin River from Pah Tempe Springs downstream to at least the Mesquite Diversion.
Virgin Spinedace
The historical distribution of the Virgin spinedace is not well documented. Holden (1977)
speculated that the species historically occurred in most of the clear water tributaries and in
several mainstem reaches of the Virgin River in southwestern Utah, northwestern Arizona,
and southeastern Nevada. Museum records obtained from the University of Nevada at Las
Vegas, Brigham Young University, University of Michigan Museum of Zoology, the United
States National Museum, and species survey information supports this description of the
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