Trouts of the Upper Kern River Basin, California, with Reference to Systematics and Evolution of Western North American Salmo

The five endemic species and subspecies of trout named from the upper Kern River drainage of the southern Sierras are revised to two subspecies of Salmo aguabonita: S. a. aguabonita and S. a. gilberti. Analysis of various characters led us to conclude that S. a. aguabonita did not differentiate from a coastal rainbow trout as surmised by other workers. This conclusion was based on: (1) morphological similarities with the inland cutthroat trout; (2) apparent relationships with the Gila, Apache, and Mexican golden trouts of New Mexico, Arizona, and northern Mexico, respectively; (3) a chromosomal complement identical to that of the Apache trout and more readily derived from that of S. clarki than from that of S. gairdneri; and (4) geomorphogeny and zoogeography of the southern Sierras. This evidence suggests the golden trout represents an ancient form whose origin was associated with a widely distributed group of goldenlike trouts.The trout originally from the Kern River has a chromosome count and a chromosome arm number identical to those of S. a. aguabonita and therefore is classified as S. aguabonita gilberti. The Little Kern golden trout, S. whitei, is considered a synonym of S. a. gilberti. Similarities with an undescribed form of the McCloud-Pit drainage of northern California suggests a common ancestry. Today, S. a. gilberti is best represented by populations in the upper Little Kern watershed. Salmo roosevelti is considered a synonym of S. a. aguabonita, and S. rosei most likely had a hybrid origin derived from introductions of S. a. gilberti and S. a. aguabonita.