A New Subspecies of Tui Chub (Osteichthyes: Cyprinidae) from Guano Basin, Nevada and Oregon

Abstract

A new subspecies of tui chub, Gila bicolor eurysoma, is described from the Guano Basin of northwestern Nevada and southeastern Oregon. Gila bicolor eurysoma is most closely allied to the undescribed subspecies of tui chub in Catlow Basin, Oregon, which supports the evi- dence for recent connections between waters of the two basins. As part of an ichthyological survey of waters in the Sheldon National Wild- life Refuge in northwestern Nevada during 1978 and 1979, we herein examine the taxonomic status of a tui chub population inhabiting an intermittent stream in the headwaters of the Guano Basin system. This population, along with another tui chub population in the Oregon part of the basin, is herein described as a new subspecies. These populations are relicts isolated when pluvial waters that dominated many valleys in the Great Basin province 10,000 to 30,000 years ago receded (Hubbs et al., 1974).