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<br />)J \lll~ <br />lq1~ <br /> <br />/ <br /> <br />Q~}q4-!l <br /> <br />THE SOUTHWESTERN NATURALIST 23(3) :511-518 <br /> <br />AUG. 10, 1978 <br /> <br />TAXONOMIC STATUS OF RHINICHTHYS <br />OSCULUS (CYPRINIDAE) IN THE <br />MOAPA RIVER, NEVADA <br /> <br />JACK E. WILLIAMS1 <br /> <br />Department ,of Biolagical Sciences, University ,of Nevada, Las Vegas, <br />Las Vegas, Nevada 89154 <br /> <br />ABSTRACT. Specimens ,of Rhinichthys asculus callected fram the Maapa River <br />between 1963 and 1967 were examined ta determine their taxanamic status rela- <br />tive ta ather papulatians of R. asculus in sauthern Nevada. The Maapa River <br />papulatian is distinct, and is regarded as a new subspecies. The new subspecies is <br />characterized by adaptatians ta its swift water habitat, including expansive, falcate <br />darsal and anal fins and expansive, deeply forked caudals. Meristically, the new <br />subspecies exhibits characteristics intermediate between thase ,of R. a. velifer and <br />R. a. yarrawi. <br /> <br />Rhinichthys osculus is considered to be the most ubiquitous fresh- <br />water fish in the western United States, with local variants inhabiting <br />an almost endless number of habitats ranging from torrential creeks <br />to isolated springs (Hubbs et al. 1974). Within the western United <br />States it is the only native fish having representatives occurring natu- <br />rally in all seven major drainage systems (Miller 1958). Habitation <br />in this rich diversity of environs has led, through adaptations, to an <br />equally diverse array of morphological variation. Nevertheless, the <br />Rhinichthys osculus complex is characterized by numerous conserva- <br />tive morphological features (Hubbs et al. 1974). <br />Several of these geographical variants of R. osculus probably war- <br />rant subspecific recognition (Hubbs, 1961; Hubbs et al. 1974). Carl L. <br />Hubbs has for some time considered the population inhabiting the <br />Moapa River of Nevada a distinct form (pers. comm.) but, until now, <br />this population has been included within the subspecies R. o. velifer. <br />The latter is endemic to the White River drainage of eastern and south- <br /> <br />1 Present address: Departmsnt ,of Fisheries and Wildlife, Oregan State University, <br />Carvallis, Oregan 97331. <br /> <br />511 <br />