|Scientific Name:||Gila ditaenia|
|Species Authority:||Miller, 1945|
|Red List Category & Criteria:||Vulnerable B1ab(iii)+2ab(iii) ver 3.1|
|Reviewer(s):||Smith, K. & Darwall, W.R.T.|
|Facilitator/Compiler(s):||Hammerson, G.A. & Ormes, M.|
This species is listed as Vulnerable because its extent of occurrence is less than 20,000 sq km, area of occupancy is probably less than 2000 sq km, number of locations may not exceed 10, and habitat quality/quantity is subject to ongoing declines.
|Range Description:||Range includes Sycamore (Bear) Canyon, Santa Cruz County, southern Arizona, and adjacent Sonora, Mexico (Rio de la Concepcion; Williams et al. 1989, Page and Burr 2011). In Arizona, this species is restricted to Sycamore Creek, Penasco Creek (intermittent flow), an unnamed tributary, and Yank's Spring (impounded, perennial), in Sycamore Canyon, and in California Gulch, west of Nogales, in the Coronado National Forest. Two pools along the unnamed tributary, just above its confluence with Sycamore Creek, support the largest concentration of this species.|
Native:Mexico; United States
|Range Map:||Click here to open the map viewer and explore range.|
This species is represented by at least several distinct occurrences (subpopulations). Minckley and Marsh (2009) mapped about 18-20 collection sites in Arizona and Mexico; these represent perhaps not more than 10 locations (as defined by IUCN).
Total adult population size is unknown. This species was common in its range in Mexico through at least the late 1980s (Miller 2005).
Trend over the past 10 years or three generations is uncertain but probably relatively stable or slowly declining. USFWS (1990) categorized the status as "stable." Conservation status was "relatively secure" in the late 1980s (Miller 2005).
|Habitat and Ecology:||Habitat includes intermittent streams; distributed throughout the stream system when flow is adequate, restricted to permanent rocky and sandy pools during dry periods; stream pools, near cliffs, boulders, or other cover in the channel; headsprings and seeps (Lee et al. 1980, Minckley and Marsh 2009, Page and Burr 2011).|
|Major Threat(s):||Threatened status is due to restricted distribution and vulnerability to habitat alteration, especially in dry years; potential threats include introduction of exotic fishes, water pollution, stream flow depletion (e.g., by humans or as a result of climate change), and siltation from mining. Apparently this species is not threatened by hybridization with another Gila species in northwestern Mexico (Copeia 1992:697-703).|
|Conservation Actions:||Better information is needed on habitat preferences, current range, and abundance. Remaining suitable habitat needs to be protected from watershed disturbances (e.g., grazing, mining, and ORV use) that cause erosion and lower water tables.|
|Citation:||NatureServe 2013. Gila ditaenia. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 30 June 2015.|