(DRAFT) - Taxonomy
                                Species CHUB, SONORA
                                Species Id ESIS252018
                                   Date 14 MAR 96



TAXONOMY

NAME - CHUB, SONORA OTHER COMMON NAMES - CHUB and SONORA ELEMENT CODE - CATEGORY - Fish PHYLUM AND SUBPHYLUM - CHORDATA, CLASS AND SUBCLASS - OSTEICHTHYES, ORDER AND SUBORDER - CYPRINIFORMES, FAMILY AND SUBFAMILY - CYPRINIDAE, GENUS AND SUBGENUS - GILA, SPECIES AND SSP - DITAENIA, SCIENTIFIC NAME - GILA DITAENIA AUTHORITY - TAXONOMY REFERENCES - COMMENTS ON TAXONOMY - Sonora Chub Gila ditaenia Miller, 1945 KINGDOM: Animal GROUP: Fish PHYLUM: Chordata CLASS: Osteichthyes ORDER: Cypriniformes FAMILY: Cyprinidae The Sonora chub (Gila ditaenia) is a fine-scaled medium-sized cyprinid in the subgenus Temeculina, genus Gila (09,11). Adults are typically less than 125 mm total length and are generally chubby and dark colored with two prominent dark lateral bands and a dark caudal spot (09,11). Pharyngeal teeth are usually 2,5-4,2 (11). The small scales are oval to rectangular and have numerous radii in all fields (09). This chub exhibits sexual dimorphism in the breeding season as noted in the species description by Miller: The axis of the pectoral and pelvic fins and the base of the anal fin were brilliant Chinese red, extending out onto these fins about two-thirds of their lengths, leaving a milky border on the outer margins. In some, there was faint evidence of red coloration at the base of rays 3 to 6 of the dorsal fin. The same red color was seen as a bright spot at the corner of the shoulder and also at the corners of Taxonomy - 1 (DRAFT) - Taxonomy Species CHUB, SONORA Species Id ESIS252018 Date 14 MAR 96 the mouth, extending straight back to the posterior edge of the preopercle. The brightest fish were orange on the sides of the belly between the bases of the paired fins, and there was a diffusion of the same color over the ventral part of the caudal rays. In noting these colors, the sexes were not separated, but the brightest fish were obviously males (09). The first known specimens were collected in 1893 by E.A. Mearns in Sycamore Canyon, Arizona (09). It was described from fish collected by R.G. Miller (1945) from the Rio Magdalena near the town of La Casita in Sonora, Mexico (16). They were identified as Richardsonius gibbosus (=Gila intermedia) by Snyder (15) and subsequently removed from synonomy (09) and placed in their current taxonomic category. The holotype, (USNM=United States National Museum) was collected in the Rio Magdalena, 460 m west of La Casita (about 40 km South of Nogales), Sonora, Mexico on 9 March, 1940 (09). Photographic illustrations appear in the original description (09) and the Fishes of Arizona (11) and a pen-and-ink drawing accompanies the species account in the Atlas of North American Freshwater Fishes (07). Taxonomy - 2
                                  (DRAFT) - Status
                                Species CHUB, SONORA
                                Species Id ESIS252018
                                   Date 14 MAR 96



STATUS

Coded Status T: Federal Threatened COMMENTS ON STATUS - U.S. STATUSES AND LAWS: The Sonora chub (Gila ditaenia) has been designated as Threatened pursuant to the Endangered Species Act of 1973 (50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540), as amended. The species has this status wherever found including the State of Arizona and Sonora, Mexico. Critical Habitat has been designated in portions of Sycamore Creek, Yank's Spring, Penasco Creek and an unnamed tributary of Sycamore Creek within the Coronado National Forest, in Santa Cruz County, Arizona (50 CFR 17.95(e)). Special rules concerning "take" for this species can be found in 50 CFR 17.44(o). This species is protected by the Lacey Act (P.L. 97-79, as amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import, export, transport, sell, receive, acquire, or purchase any wild animal (alive or dead including parts, products, eggs, or offspring): (1) in interstate or foreign commerce if taken, possessed, transported or sold in violation of any State law or regulation, or foreign law; or (2) if taken or possessed in violation of any U.S. law, treaty, or regulation or in violation of Indian tribal law. It is also unlawful to possess any wild animal (alive or dead including parts, products, eggs, and offspring) within the U.S. territorial or special maritime jurisdiction (as defined in 18 U.S.C. 7) that is taken, possessed, transported, or sold in violation of any State law or regulation, foreign law, or Indian tribal law. RESPONSIBLE FEDERAL AGENCIES: USFWS -Responsible for the management/recovery, listing, and law enforcement/protection of this species. USFS -Responsible for the law enforcement/protection of this species with applicable State and Federal laws on public lands under their control. Also responsible for management/recovery on Forest Service lands. The Forest Service is responsible for integrating management, protection, and conservation of Federally listed species into the Forest Planning process (36 CFR 219.19 and 219.20). Management practices that would cause detrimental changes in water temperature or composition, water course blockage, or sediment Status - 1 (DRAFT) - Status Species CHUB, SONORA Species Id ESIS252018 Date 14 MAR 96 deposits within 100 feet of the edges of perennial streams, lakes or other bodies of water are prohibited (36 CFR 219.27(e)). All Federal agencies have responsibility to ensure that any action authorized, funded, or carried out by that agency is not likely to jeopardize the continued existence of the species or result in the destruction or adverse modification of Critical Habitat (50 CFR 402), and to utilize their authorities to carry out programs for the conservation of the species. STATE STATUSES AND LAWS: STATE: Arizona DESIGNATED STATUS: Group 3, Threatened Native Wildl. in Arizona ADMINISTRATIVE AGENCY: Arizona Fish and Game Department STATE STATUTE: Ariz. Rev. Stat., Sec. 17-231(B)7. INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS: This fish is listed as vulnerable in the 1986 Red List of Threatened Animals. It was also previosly listed under the scientific name Gila intermedia in the 1977 IUCN Red Data Book. ECONOMIC STATUSES: This species has a value as a component of Arizona's natural heritage of biotic diversity. 82/12/30:47 FR 58454/58460 - Notice of review 84/06/06:49 FR 23402/23408 - Proposed rule - Threatened w/ Crit. Hab. 86/04/30:51 FR 16042/16047 - Final rule - Threatened w/ Crit. Hab. Status - 2
     

HABITAT ASSOCIATIONS

HABITAT - AQUATIC INLAND AQUATIC LAND USE - Shrub and Brush Rangeland Mixed Rangeland Evergreen Forest Land Mixed Forest Land Streams and Canals Bare Exposed Rock NATIONAL WETLAND INVENTORY CODES NWI NWICLS NWIMOD NWISPEC Riverine, upper perennial Riverine, lower perennial RB2 Riverine, lower perennial RB1 Riverine, lower perennial RB Riverine, lower perennial COMMENTS ON HABITAT ASSOCIATIONS - In the United States, the Sonora chub is known from Sycamore Creek below Yanks Spring (11,12) and in two of its tributarys located on Coronado National Forest northwest of Nogales, Santa Cruz County, Arizona (16). The Yank's spring is a lower perennial spring which has been impounded in a concrete tank and lacks a riparian zone (16). In Sycamore Canyon, the Sonora chub is abundant to common in deep pools some of which are closely adjacent to protective cover such as undercut banks, boulders or tree roots (10,11,16). Sycamore Creek forms a series of pools and small riffles over a bedrock and rubble substrate (10,11,16). The preferred habitat of this species appears to be in a relatively unaltered state (16). The surrounding riparian vegetative cover along the Sycamore Creek includes both pinyon/juniper and chaparral rangeland with a oak woodland forest type (18). The predominant trees include sycamores, willows, cottonwoods, and the Arizona walnut (18). All age group stands are present as a result of controlled grazing and erosion (18). Known primary constituent elements include clean permanent water with pools and intermediate riffle areas and/or intermittent pools maintained by bedrock or by subsurface flow in areas shaded by canyon walls (16). Annual discharge in Sycamore Creek can vary considerably. During high flow new habitat is created in ephemeral reaches but for some unknown reason the chub does not occupy the newly formed pools (11). The lack of specimens in "seemingly" good habitat has resulted, on occasion, in the erroneous conclusion that the species is extirpated from the site (14). During low or intermittent flows, pools are maintained by underground flows (02,08,11). The Sonora chub is also able to survive under severe conditions as in 1964, when a few dwarfed individuals were discovered 2 km north of Yanks Spring in a seep containing only a few liters of water (11). The seep, almost overgrown with plants except where cattle had trampled, had a foul, black reducing substrate (11). The type locality in Sonora, Mexico was a clear stream 1.22-1.5 m and approximately 30 cm deep with a swift current over a sand/gravel substrate (09). The dominant vegetation at this site was watercress Habitat Associations - 1 (09). Water quality taken at Yanks Spring in 1982 yielded the following physical parameters (02): Temperature 25 C Turbitity (NTU) 7 pH 6.3 Specific conductivity 245 Hardness (CaCO3) 130 Cations (mg/l) Magnesium 8.3 Sodium 32.3 Potassium 4.4 Anions (mg/l) Alkalinity (CaCO3) 120.9 Chloride 7.6 Nitrate 0.04 Phosphate trace Ammonia 0.05 Sulfate 10.7 Trace metals (mg/l) Copper 50 Iron 100 Magnese 50 Silver 50 Zinc 10 Habitat Associations - 2
                                (DRAFT) - Food Habits
                                Species CHUB, SONORA
                                Species Id ESIS252018
                                   Date 14 MAR 96



FOOD HABITS

TROPHIC LEVEL - OMNIVORE LIFESTAGE FOOD FOOD PART General Algae General Arthropods Food Habits - 1
                         (DRAFT) - Environment Associations
                                Species CHUB, SONORA
                                Species Id ESIS252018
                                   Date 14 MAR 96



ENVIRONMENTAL ASSOCIATIONS

G = General A = Adult LIM = Limiting RA = Resting Adult J = Juvenile FA = Feeding Adult RJ = Resting Juvenile BA = Breeding Adult FJ = Feeding Juvenile P = Pupae L = Larvae E = Egg RL = Resting Larvae FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS G Aquatic Features: Pool areas G Aquatic Features: Springs [flowing] G Terrestrial Features: Rock outcrops Environment Associations - 1
                               (DRAFT) - Life History
                                Species CHUB, SONORA
                                Species Id ESIS252018
                                   Date 14 MAR 96



LIFE HISTORY

FOOD HABITS: Dietary information on the Sonora chub is based on gut analysis of a few Arizona specimens collected during the early summer (11). Aquatic and terrestrial insects and algae (in decreasing order of volume) were found in the gut (11). HOME RANGE/TERRITORY: This species is thought to behave like other southwestern chubs in the genus Gila and have highly secretive habits (10). No other information is available. PERIODICITY: No studies have been conducted which investigated the periodicity or seasonal activity of the Sonora chub. MIGRATION PATTERNS: There is nothing known about the daily or seasonal migratory patterns of the Sonora chub. COVER/SHELTER REQUIREMENTS: No additional data, besides that included in the "HABITAT ASSOCIATION" section are available on the Sonora chubs requirements for cover or shelter during any of its life history phases. Sonora chub is abundant to common in deep pools some of which are closely adjacent to protective cover such as undercut banks, boulders, or tree roots (Sycamore, cottonwoods, willows) (10,11,16,18). Known primary constituent elements include clean permanent water with pools and intermediate riffle areas and/or intermittent pools maintained by bedrock or by subsurface flow in areas shaded by canyon walls (16). REPRODUCTIVE SITE REQUIREMENTS: Little data is available on the reproductive biology of the Sonora chub. They probably spawn in the early spring (February-April) (11). This information is based on the presence of young individuals in preserved collections (11). Recent evidence indicates that the chub spawns in September-October (05). REPRODUCTIVE CHARACTERISTICS: No information is available on the reproductive characteristics of this species. PARENTAL CARE: There is no information on parental care of the eggs or larvae of Sonora chub. POPULATION BIOLOGY: Nothing is known about the population biology of this form. SPECIES INTERRELATIONSHIPS: The only other native fish taken in the United States in association with the Sonora chub is the longfin dace (Agosia Life History - 1 (DRAFT) - Life History Species CHUB, SONORA Species Id ESIS252018 Date 14 MAR 96 chrysogaster) and it is rare in collections (11). The introduced green sunfish and mosquitofish (Gambusia affinis) have been collected within the range of the Sonora chub but at present, only the green sunfish still persists (10,16). It is assumed that the sunfish escaped from stock-tanks in the drainage (01,05). In 1986 in Mexico, the Rio Concepcion (=Rio Asuncion) basin was surveyed and three native species of fishes were collected: longfin dace, Sonoran topminnow (Poeciliopsis o. occidentalis) and an undescribed species of topminnow (Poeciliopsis) along with three introduced species (green sunfish, largemouth bass (Micropterus salmoides) and black bullhead (Ictalurus melas)) (03). The Yaqui chub, native to the Rios Yaqui, Matape and Sonora and also recently introduced into the Rio Magdalena, was not taken in the 1986 survey (04). The collections indicated that hybridization between these two species may be occurring in at least one location (04). The spread of the Yaqui chub throughout the drainage could result in the loss of the Sonora chub through hybridization (04). OTHER LIFE HISTORY DESCRIPTORS: None. Life History - 2
                           (DRAFT) - Management Practices
                                Species CHUB, SONORA
                                Species Id ESIS252018
                                   Date 14 MAR 96



MANAGEMENT PRACTICES

RESULT MANAGEMENT PRACTICE Beneficial Controlling/Restricting Off-Road Vehicles Beneficial Restricting/regulating human disturbance of populations Beneficial Controlling/Restricting Mining Beneficial Water Right Acquisition Beneficial Controlling pollution [thermal, chemical, physical] Beneficial Stocking captive-reared wild-strain animals Beneficial Controlling/Removing Domestic Animals Adverse Low Gene Pool Existing Low Gene Pool Adverse Hybridization Existing Hybridization Adverse Disease Existing Disease Adverse Parasites Existing Parasites Adverse Predation Existing Predation Adverse Underground Mines Existing Underground Mines Adverse Surface Mines Existing Surface Mines Adverse Recreational development Existing Recreational development Adverse Water Level Fluctuation Existing Water Level Fluctuation Adverse Exotic/Feral/Introducted Species Existing Exotic/Feral/Introducted Species COMMENTS ON MANAGEMENT PRACTICES - The Sonora chub lives in a small section of southern Arizona and northern Sonora, Mexico (09,12). Sycamore Creek, the United States range of the chub, is a small, short stream less than 7.5 km long and subject to intermittent droughts and flash floods (02,08). The chubs limited distribution and apparently narrow ecological niche make it very susceptible to any habitat disturbances (i.e., mining, recreation) especially during periods of low flow depletion of stream flow, the introduction of manmade pollutants and subsequent increased siltation and runoff (10). Currently, these disturbances have not had an effect on the Sonora chubs habitat. A reduced gene pool compounds these problems even more. Anthropogenic activities in Sycamore Canyon are limited to non-developed and dispersed uses (16). In 1981, uranium was found in the upper slope of the Sycamore drainage (16). These mining claims, approximately 4-5 square miles, are still being maintained but there are no plans to reopen the mines (16). The region is presently closed to grazing and mineral exploration but in California Gulch, just on watershed to the west, there were recent mining activities (16). Another important threat to the continued existence of the Management Practices - 1 (DRAFT) - Management Practices Species CHUB, SONORA Species Id ESIS252018 Date 14 MAR 96 Sonora chub is the introduction of predatory exotics and the parasites and diseases for which they may be hosts (10). In the United States, the green sunfish (Lepomis cyanellus) is the only known introduced form which still exists in Sycamore Creek (01,10,16). Mosquitofish was reported from the Canyon (16) but apparently died out. In Mexico, there are at least four other species present within the Sonora chub's range (04,16). The adverse impacts of parasites and disease associated with exotic fish has been well documented and would probably also occur with Sonora chub (06,13,17). In Mexico, there is a report of the Yaqui chub (Gila purpurea), an introduced form, hybridizing with the Sonora chub in at least one location (04,10,16). The spread of this species throughout the Rio Magdalena could result in the loss of the Sonora chub through hybridization (04,10,16). Timber harvesting is not considered a threat due to the lack of desirable tree types in and around the Sycamore Creek area (18). UNAPPROVED PLAN: U.S. Fish and Wildlife Service. 1987. Sonora chub Recovery Plan. Tech. Draft. U.S. Fish and Wildl. Serv., Albuquerque, NM. 29 pp. The Sonoran chub is relatively secure in the small area occupied in the United States due to Federal ownership and special-use designation already provided its habitats and the surroundings. However, because of the limited amount of available habitat, it is doubtful that any significant increase in populations can be accomplished in this country. The recovery of the species is dependent upon efforts to protect and set aside a portion of Sonora chub range in Mexico. The plan calls for monitoring of existing Sonora chub populations by annual pre- (February) or post-breeding (August) surveys of occupied habitat and documentation of habitat conditions using standardized methods. Studies of population requirements to determine: 1) reproductive variables, 2) effects of predation and competition, 3) survivorship by age group, 4) diseases and parasites, and 5) other factors (behavioral, physiological) relevant to perpetuation of the species are needed. Current activities in Sycamore Canyon are generally restricted to bird-watching, hiking, and other forms of recreation. Human access is limited to hiking and horseback trails. The canyons that contain Critical Habitat, however, do receive heavy visitor use. Yank's Spring is the site of a trailhead parking lot for visitors, but the spring has been impounded in a concrete tank for many years and is resistant to habitat damage. The Critical Habitat area is included in a livestock grazing allotment, but the steep and rocky topography generally precludes grazing along the stream banks within the riparian zone portion of Management Practices - 2 (DRAFT) - Management Practices Species CHUB, SONORA Species Id ESIS252018 Date 14 MAR 96 Critical Habitat. Therefore, livestock grazing is not expected to affect the Sonora chubs Critical Habitat designation. The U.S. Forest Service controls and restricts any possible grazing attempts made by domestic animals. The remaining portion of Sycamore Creek Critical Habitat flows through the Gooding Research Natural Area (GRNA). The GRNA was established on July 8, 1970, to protect unique species. Consequently, the Goodding Research Natural Area is withdrawn from mineral entry and is closed to grazing. Another important threat to the continued existence of the Sonora chub is the introduction of predatory exotics and the parasites and diseases for which they may be hosts. In the United States, the green sunfish (Lepomis cyanellus) is the only known introduced form which still exists in Sycamore Creek. The threat is only possible and is currently not being controlled. The U.S. Forest Service restricts all off-road vehicle use in and around any part of the surrounding habitat which is contained in the Coronado National Forest. There has been no attempt to control or maintain water flow or the water table due to the lack of demand on water resources. Timber harvesting is not a problem due to lack of desirable tree types. Currently, no mining is occurring in the Sycamore Creek drainage within or in the vicinity of the Critical Habitat. There are, however, mining claims within the drainage in the vicinity. The Bureau of Land Management (BLM) is the issuing agency and the Forest Service is the surface resources management agency for these claims held by Uranerz USA Incorp., and Tennessee Valley Authorities. Mining these or other claims might adversely affect the designated Critical Habitat if mining activities resulted in increased sediment transport and pollution. Submission of a detailed Plan of Operation to the Forest Service and the BLM for approval is required prior to mining. Sonora chub habitat should be maintained and enhanced by: 1) determining and protecting water-rights/potential water-use patterns, 2) determining precipitation-runoff relationships, and 3) evaluating relationships of runoff-instream flow needs. Surveys of present and potential aquatic habitat should include an evaluation of: 1) physical, 2) chemical, and 3) biological features. Information on diel, seasonal, and annual distribution of Sonora chub life-history stages is also needed. It is important to maintain a reserve population of Sonora chub, since it presently is known to occur in only one drainage in the U.S. To establish the reserve population, it is important to determine the population size required to duplicate genetic diversity in the wild and the requirements for maintaining heterozygosity in genetic reserves. A refugium population of the U.S. population should be Management Practices - 3 (DRAFT) - Management Practices Species CHUB, SONORA Species Id ESIS252018 Date 14 MAR 96 maintained at Dexter National Fish Hatchery or other suitable facility and a reserve of Mexican stock chubs should also continue to be maintained (presently at the Sonoran Desert Museum and at Gobierno del Estado de Sonora in Hermosilla, Sonora, Mexico). The plan also calls for: 1) enforcement of all Federal and Arizona laws protecting the species, and 2) development of public support through an information and education program that should include: a) preparation of an information pamphlet, b) new releases to the media, and c) development of an interpretive program at the U.S. Forest Service's Godding Research Natural Area, which includes all of the occupied habitat in the United States. Management Practices - 4
                                   (DRAFT) - References
                                   Species CHUB, SONORA
                                  Species Id ESIS252018
                                      Date 14 MAR 96



     

References

***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE ***** 01 Bell, G. 1984. Sonora chub, Sycamore Canyon. U.S. For. Serv., Nogales Ranger Dist., Coronado Nat. For., inter-office memo., Nogales, AZ. 13 pp. 02 Brooks, J.E. 1982. Sycamore Creek survey- Gila ditaenia. Ariz. Game and Fish Dept., inter-office memo., Phoenix, AZ. 2 pp. 03 U.S. Fish and Wildlife Service. 1987. Sonora chub Recovery Plan. Tech. Draft. U.S. Fish and Wildl. Serv., Albuquerque, NM. 25 pp. 04 Hendrickson, D.A. 1984. Distributional records of native and exotic fishes in Pacific drainages of northern Mexico. J. of the Ariz./Nevada Acad. of Sci. 18:33-38. 05 Hendrickson, D.A., and L. Juarez Romero. In prep. Fishes of the Rio Concepcion basin, Sonora, Mexico. 06 James, A.E. 1968. Learnea (copepod) infection of three native fishes from the Salt River basin, Arizona. Unpubl. Ms. of Sci. Th. Ariz. State Univ., Tempe. 07 Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins, D.E. McAllister and J.R. Stauffer, Jr. (eds). 1980. Atlas of North American Freshwater Fishes. N. Carol. State Mus. of Nat. Hist., Raleigh. 08 Miller, L. 1949. Field notes on the minnow, Gila ditaenia, in southern Arizona. Copeia 1949:148-150. 09 Miller, R.R. 1945. A new cyprinid fish from southern Arizona and Sonora Mexico, with a description of a new subgenus of Gila and a review of related species. Copeia 1945:104-110. 10 Minckley, C.O. 1983. Status report on Gila ditaenia. U.S. Fish and Wildlife Service, Albuquerque, NM. 14 pp. 11 Minckley, W.L. 1973. Fishes of Arizona. Ariz. Game and Fish Dept., Phoenix, AZ. 12 Minckley, W.L. 1985. Native fishes and natural aquatic habitats in U.S. Fish and Wildlife Region II, west of the Continental Divide. Rept. to the U.S. Fish and Wildl. Serv., Albuquerque, NM. 158 pp. 13 Minckley, C.O., S.W. Carothers, J.W. Jordan, and H.D. Usher. 1981. Observations on the humpback chub, Gila cypha, within the Colorado and Little Colorado Rivers, Grand Canyon National Park, Arizona. November 1979, Nat. Park Serv. Transactions and Proceedings Series. 14 Minckley, W.L., and J.E. Deacon. 1968. Southwestern fishes and the enigma of endangered species. Science 159:1424-1432. 15 Snyder, J.O. 1915. Notes on a collection of fishes made by Dr. Edgar A. Mearns from rivers tributary to the Gulf of California. Proceedings of the U.S. Nat. Mus. 49:573-586. 16 U.S. Fish and Wildlife Service. 1986. Endangered and threatened wildlife and plants; final rule to determine the Sonora chub to be a threatened species and determine its critical habitat. Fed. Reg. 51:16042-16047. 17 Wilson, B.L., J.E. Deacon, and W.G. Bradley. 1966. Parasitiswm in the fishes of the Moapa River, Clark County, Nevada. Desert Res. Instit., Univ.. of Nevada, Las Vegas. 18 Burton, J. 1987. Pers. knowledge. U.S. Fish and Wildl. Serv., Albuquerque, NM. References - 1 (DRAFT) - References Species CHUB, SONORA Species Id ESIS252018 Date 14 MAR 96 ***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY ***** 01 Bell, G. 1984. Sonora chub, Sycamore Canyon. U.S. Forest Serv., Nogales Ranger District, Coronado Nat. For., Nogales, AZ. 13 pp. 02 Hendrickson, D.A. 1984. Distribution records of native and exotic fishes in Pacific drainages of northern Mexico. J. of the Ariz.- Nevada Acad. of Sci. 18:33-38. 03 Miller, L. 1949. Field notes on the minnow, Gila ditaenia, in southern Arizona. Copeia 1949:148-150. 04 Miller, R.R. 1945. A new cyprinid fish from southern Arizona and Sonora, Mexico, with a description of a new subgenus of Gila and a review of related species. Copeia 1945:104-110. 05 Minckley, W.L. 1973. Fishes of Arizona. Ariz. Game and Fish Dept., Phoenix, AZ. 06 Minckley, W.L. 1980. Gila ditaenia Miller. Sonora chub. IN: Lee, D.S., C.R. Gilbert, et al. Atlas of North American Freshwater Fishes. N. Carolina State Mus. of Nat. Hist., Raleigh, NC. 07 Minckley, W.L. 1985. Native fishes and natural aquatic habitats in U.S. Fish and Wildlife Region II, west of the continental divide. Rept. to the U.S. Fish and Wildl. Serv., Albuquerque, NM. Dept. of Zool., Univ. of Ariz., Tempe, AZ. 158 pp. 08 U.S. Fish and Wildlife Service. 1987. Sonora chub Recovery Plan. Review Draft. U.S. Fish and Wildl. Serv., Albuquerque, NM. 25 pp. References - 2