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Gila bicolor euchila: Fish Creek Springs Tui Chub This subspecies has been restricted to a single cold water spring system in this valley, as recent surveys conducted in 1978 and 1979 found that no other springs in the valley contained native species. The single system is heavily impacted by the cattle ranching operations, and Salmo gairdneri were evident in all the springs except the one remaining locality where the chubs were found. The loss of this animal throughout most of its former distribution in this system, as well as the presence of the introduced trout, should warrant an endangered or threatened status. Rehabilitation and reintro- duction of the chub should be considered. Gila bicolor isolata: Independence Valley Tui Chub The current status of this subspecies is unknown at this time and field reconnaissance of the habitat should be undertaken. No other collections from Independence Valley are known, and its recommended status is threatened or endangered. The continued alterations of habitat and the MX missile are of primary concern for this species. Gila bicolor newarkensis: Newark Valley Tui Chub The original three localities reported by Hubbs and Miller (1974) now contain chubs only at one location: on the Goecoechia Ranch. Surveys con- ducted by Gail Kobetich (USFWS) and myself in 1978 have produced nine new localities along the eastern escarpment of pluvial Lake Newark. These isolated spring systems are rather small and heavily choked with aquatic plants, and many of the outflows persist for only a few meters. The limited size of the habitats and potential threats of the MX missile deployment in this region of the state, and possible modifications for livestock, warrant that this subspecies be listed as special concern or threatened. Gila bicolor obesa: Lahontan Creek Tui Chub This species is known from only two localities in Diamond Valley: Thompson (Birch) Ranch and Sulphur Springs. The chub was reported extirpated from the latter location in 1976 by Jim Deacon (UNLV). He also documented the intro- duction of bass and carp into this system. The status of the remaining popu- lation and the increased pressures exerted on it warrants that the animal be listed as threatened or endangered. The proposed deployment of the MX missile project in this area and the continued development of the habitats for livestock and agricultural purposes are the primary concerns for this species. Gila bicolor ssp.: The several undescribed subspecies that inhabit both Hot" Creek Valley and Railroad Valley are in need of taxonomic clarification. Those present in Rail- road Valley upon examination in October of 1979 showed a wide variation in morphology. Because several of these populations have probably been separated over the last several thousand years, they are probably subspecifically dif- ferentiated. Surveys throughout Railroad Valley did not produce any new localities in October of 1979. Chubs at Bull Creek, however, have been extirpated since Deacon's collection in 1977. All the other localities still contained chubs, but habitat alterations and exotic fish introductions were wide- spread. The MX missile, oil field developments, and pressures from livestock and agricultural demands mandate that more life history information be gathered