Cyprinella formosa

Removed from genus Notropis and placed in genus (formerly subgenus) Cyprinella by Mayden (1989); this change was adopted in the 1991 AFS checklist (Robins et al. 1991). Has been regarded as a subspecies of N. lutrensis by some, but found to be distinct by Mayden (1989) and Chernoff and Miller 1982); more closely related to C. bocagrande than to C. lutrensis (Mayden 1989). Synonyms include Notropis santamariae Evermann and Goldsborough and Notropis mearnsi Snyder.

Occurs in several basins in southeastern Arizona and northwestern Mexico; fairly large range in Mexico but probably declining there, due mainly to dewatering and pollution caused by agriculture; better information is needed on status in Mexico; non-indigenous fishes, especially the red shiner, may be having a negative impact; reintroduction in southeastern Arizona has been successful, and reintroduction in New Mexico is planned.

Historical range encompassed northern Mexico (Sonora, Chihuahua), southeastern Arizona (San Bernardino Creek, Black Draw Creek, and associated artesian wells and cienegas, Rio Yaqui basin; extirpated by 1970), and southwestern New Mexico (Mimbres River; disappeared after 1951) (Sublette et al. 1990, Miller 2005). Mexico contains almost all of the historical range, which extended into small portions of the United States. Current range in Mexico includes the Guzman basin (including rios Casas Grandes, Santa Maria, and del Carmen), and Yaqui, Bavicora, and Sauz basins (current status in Sauz Basin is unknown). Elevational range in Mexico is 800-1,700 meters (2,625-5,580 feet), and historically in Arizona the species occurred at approximately 1,158 meters (3,800 feet) (Arizona Game and Fish Department 1994). The species has been reintroduced and is thriving in refugia on the San Bernardino National Wildlife Refuge, Arizona (USFWS 1994). Stocks occur also at the Dexter National Fish Hatchery & Technology Center, Dexter, New Mexico. See USFWS (1994).

TNHC (1996) mapped 15 locations, including 2 in New Mexico, 1 in Arizona, and 2 in northern Mexico. Miller (2005) mapped about 4 dozen collection sites (representing at least two dozen distinct occurrences) in Mexico but did not comment on current status. Extirpated in Arizona by 1970; reintroduced into 4 small ponds in 1990; reintroduced populations are breeding and in excellent condition (S. Schwartz, pers. comm., 1997). Extirpated in New Mexico.

Demise in New Mexico probably was due to ephemeral stream flows resulting from drought conditions and diversion of water for agricultural purposes (Sublette et al. 1990). The species was extirpated from San Bernardino Creek, Arizona, when the creek dried up as a result of groundwater pumping; remaining habitat was further degraded by livestock. Leasing of geothermal resources in the San Bernardino Creek area potentially threatens water supply and quality.

Surveys in 1979 found populations of this species to be seriously depleted in the Mexican portion of the historical range (Matthews and Moseley 1990); the decline was due to water development for agriculture, chemical and sewage pollution, and impacts of non-native species (USFWS 1994).

Populations are vulnerable to extirpation or reduction as a result of interactions with introduced non-native species. Introduced red shiner (Notropis lutrensis) appears to be reducing populations of the beautiful shiner through competition and interbreeding. A potential problem is predation by introduced bullfrogs (Arizona Game and Fish Department 1994).

Jelks et al. (2008) categorized this species as Threatened due to (1) present or threatened destruction, modification, or reduction of habitat or range and (2) other natural or anthropogenic factors that affect existence, including impacts of nonindigenous organisms, hybridization, competition, and/or predation.