(DRAFT) - Taxonomy
                            Species PUPFISH, LEON SPRINGS
                                Species Id ESIS252009
                                   Date 14 MAR 96



TAXONOMY

NAME - PUPFISH, LEON SPRINGS OTHER COMMON NAMES - PUPFISH and LEON SPRINGS ELEMENT CODE - CATEGORY - Fish PHYLUM AND SUBPHYLUM - CHORDATA, CLASS AND SUBCLASS - OSTEICHTHYES, ORDER AND SUBORDER - ATHERINIFORMES, FAMILY AND SUBFAMILY - CYPRINODONTIDAE, GENUS AND SUBGENUS - CYPRINODON, SPECIES AND SSP - BOVINUS, SCIENTIFIC NAME - CYPRINODON BOVINUS AUTHORITY - TAXONOMY REFERENCES - COMMENTS ON TAXONOMY - Leon Springs Pupfish Cyprinodon bovinus Baird and Girard, 1853 KINGDOM: Animal GROUP: Fish PHYLUM: Chordata CLASS: Osteichthyes ORDER: Atheriniformes FAMILY: Cyprinodontidae Cyprinodon bovinus is a relatively small pupfish [adults reach up to approximately 50 mm standard length (SL)] that differs from most other species of Cyprinodon in having a wider head and body (02). The species appears most similar to C. tularosa, found in an isolated basin west of Alamogordo, New Mexico. However, C. bovinus differs considerably from C. tularosa in a number of scale counts and body proportional measurements (02). Three other Cyprinodon occupy portions of the Pecos River Basin in addition to C. bovinus, and these may be distinguished from the Leon Springs pupfish as follows: Cyprinodon variegatus (the sheepshead minnow, introduced from coastal waters) has pronounced vertical bars on its sides and trunk which are lacking in C. bovinus; C. elegans (the Comanche Springs pupfish) has a peculiar speckled color pattern, unique among Cyprinodon; and C. pecosensis (the Pecos pupfish) does not possess the fully scaled abdomen and the bright yellow pigment on Taxonomy - 1 (DRAFT) - Taxonomy Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 the dorsal and caudal fins in breeding males that are present in C. bovinus (02,03,04). In addition, electrophoretic analysis by Williams (05) indicate that C. bovinus is distinct from each of the above species, as well as other Cyprinodon. Much of the type material appears to be lost from the U.S. National Museum (02), however 5 syntypes from the original collection of C. bovinus are extant and recorded in Echelle and Miller's redescription of this species (02). In this redescription, diagnostic characters are noted and a photograph of a male and female are included. Specimens for comparison are stored at various museums including: the University of Michigan's Museum of Zoology (UMMZ), the University of Texas at Austin's Texas Natural History Collection (TNHC), the University of Oklahoma's Museum of Zoology, Harvard University (3 syntypes, MCZ 1297), U.S. National Museum (1 syntype, USNM 154785) and the Paris Museum (1 syntype, cat. no. 682) (02). Taxonomy - 2
                                  (DRAFT) - Status
                            Species PUPFISH, LEON SPRINGS
                                Species Id ESIS252009
                                   Date 14 MAR 96



STATUS

Coded Status E: Federal Endangered COMMENTS ON STATUS - U.S. STATUSES AND LAWS: The Leon Springs pupfish (Cyprinodon bovinus) has been designated an Endangered species 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 Texas. Critical Habitat has been designated at Diamond Y Spring and its outflow, Leon Creek downstream to 1 mile NE of the Texas Highway 18 crossing in Pecos County, TX (50 CFR 17.95(e)). 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 (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. 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: Texas DESIGNATED STATUS: Endangered ADMINISTRATIVE AGENCY: Texas Parks and Wildlife Department Status - 1 (DRAFT) - Status Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 STATE STATUTE: 31 Texas Administrative Code Sec. 57.133 (127.30.003) July 1977 INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS: The Leon Springs pupfish is listed as Endangered in the IUCN Red Data Book, Vol. 4, 1977. ECONOMIC STATUSES: This species has value to naturalists and as a component of Texas' natural heritage of biotic diversity. 78/08/15:43 FR 36117/36120 - Proposed Endangered w/ Critical Habitat 79/03/06:44 FR 12382/12384 - Wthdrawal of Critical Habitat proposal 80/05/16:45 FR 32350/32353 - Reproposal of Critical Habitat 80/08/15:45 FR 54678/54681 - Listing as Endangered w/ Critical Habitat 85/07/22:50 FR 29901/29909 - Five year review Status - 2
     

HABITAT ASSOCIATIONS

HABITAT - AQUATIC INLAND AQUATIC LAND USE - Transportation, communications, and Util Cropland and Pasture Herbaceous Rangeland Streams and Canals Nonforested Wetland NATIONAL WETLAND INVENTORY CODES NWI NWICLS NWIMOD NWISPEC Riverine, intermittent SB Riverine, upper perennial SB3 Riverine, upper perennial AB1 Palustrine AB Palustrine EM COMMENTS ON HABITAT ASSOCIATIONS - The Leon Springs pupfish inhabits the quiet, shallow waters along the edges of Leon Creek, Diamond-Y Springs, the associated marsh habitats resulting from the spring outflows, and natural spring seeps and pools along the watercourse (06,07,09,10). A downstream watercourse is (except during storms) separated from an upstream watercourse by about 1.5 km of dry creekbed. The watercourse terminates in a small playa pond that is often dry (06). The habitats that C. bovinus presently occupies include relatively stenothermal (17 to 20 degrees C) springs and seeps which are relatively saline (ca 15 ppt total dissolved solids, primarily MgSO4) with recorded conductivities as high as 18,000 microhms/cm (08). Leon Springs pupfish are found in a variety of shallow water habitats and temperatures have been found to vary from 3 to 35 degrees C (07). Due to the high salinities, few trees grow along the water course (09), however, seasonally abundant filamentous algae, Scirpus and Chara are found in or along the creekbank (07,10). Substrates are mostly hard clay and soft to flocculent muds (07,09, 10). After periodic heavy rains, the creek bottom is scoured and bedrock exposed (09). Following hatching, the young move into shallow water environments near the creek edge and into the outskirts of the marsh margin (07). An oil and natural gas field is located adjacent to Diamond-Y Springs and Leon Creek (02,07,08,09,10) and a protective dike has been constructed between the oil/gas field and Diamond-Y Springs to prevent accidental contamination. Rangeland in the area is characteristic of southwestern shrubsteppe, associated wetlands are nonforested, and agricultural uses include croplands (sorghum and cotton) and pasture. Texas Highway 18 and other roads cross over the habitat area. Habitat Associations - 1
                                (DRAFT) - Food Habits
                            Species PUPFISH, LEON SPRINGS
                                Species Id ESIS252009
                                   Date 14 MAR 96



FOOD HABITS

TROPHIC LEVEL - OMNIVORE LIFESTAGE FOOD FOOD PART General Detritus General Poaceae General Zooplankton General Arthropods General Crustaceans General Molluscs General Diatoms General Algae Food Habits - 1
                         (DRAFT) - Environment Associations
                            Species PUPFISH, LEON SPRINGS
                                Species Id ESIS252009
                                   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] Environment Associations - 1
                               (DRAFT) - Life History
                            Species PUPFISH, LEON SPRINGS
                                Species Id ESIS252009
                                   Date 14 MAR 96



LIFE HISTORY

FOOD HABITS: Cyprinodon bovinus is quite generalized in its food habits, as are most members of the genus (07). Foods that were taken in a sample of 40 Leon Springs pupfish collected during June to October included diatoms, algae, marl, amphipods, gastropods, ostracods, coleopterans and seeds in decreasing order of occurrence in the gut samples (07). Almost all individuals contained diatoms, algae, and marl, with lesser numbers containing the other food types (07). HOME RANGE/TERRITORY: Male Cyprinodon bovinus often maintain breeding and/or feeding territories and aggressively defend these from intruders (07). Territories (actually "pits" that are dug into the substrate) range from 4 to 10 cm wide and 2 to 6 cm deep and are generally round with steep walls and relatively rounded bottoms (07). It has been suggested that these territories are associated with the locating of buried food items (11). During winter cold periods, there is some evidence that C. bovinus may either migrate upstream to stenothermal spring seeps which could provide moderating temperatures, or may bury into the relatively flocculent muds (07,10). PERIODICITY: Leon Springs pupfish activity levels are dependent upon water temperatures (06,07,09,10). The average critical thermal minimum ranges from -0.2 to 2.4 degrees C depending upon the time of day (lower in the morning) as well as season (higher in the summer) (07). Similar patterns were found for critical thermal maximums which ranged from an average of 36.8 to 41.5 degrees C (07). In addition, spawning appears to be greatest during summer months and during this period, two spawning peaks (mid-morning and mid-afternoon) per day have been suggested (07). MIGRATION PATTERNS: Extensive migrations are not known for the Leon Springs pupfish, however short migrations toward warmer spring seeps or into thermally moderating muds during winter has been suggested (06,07,09,10). In general, these migrations would be a minimal distance (1 to 5 m) (07, 10). COVER/SHELTER REQUIREMENTS: The Leon Springs pupfish is seldom found near cover or shelters with the exception of the loose substrate muds of the creek which are used for territories by breeding males and as a refugium during winter (06,07). REPRODUCTIVE SITE REQUIREMENTS: Leon Springs pupfish males dig pits (07,11) and aggressively defend these feeding territories from intruders. It is hypothesized that these "pits" may also function as display areas for breeding (07). Eggs are presumably laid on the bottom substrate inside these Life History - 1 (DRAFT) - Life History Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 shallow territories or in and amongst the Scirpus or filamentous algae beds which remain defended by the males (06,07). REPRODUCTIVE CHARACTERISTICS: Cyprinodon bovinus mature at approximately 29 mm SL (07). Mean egg diameters reach a maximum (3.8 mm) during July, however, reproduction has been observed throuthout the year (07,09). Fecundity information for the Leon Springs pupfish, including the number of eggs produced and the frequency of egg production are unknown (06). There appears to be little discrimination among males of different species of Cyprinodon by Leon Springs pupfish females based on laboratory mate-choice experiments (12). PARENTAL CARE: The Leon Springs pupfish males guard spawned eggs in their territorial "pits" (06,07). Development of the eggs is dependent upon water temperatures and an egg may take up to 2 to 3 weeks or more to hatch (based upon the time that peak spawning is observed and young of the year were first captured) (07). Following hatching, the young move into shallow water environments near the creek edge and into the outskirts of the marsh margin (07). POPULATION BIOLOGY: Several limiting factors are known or suspected for Cyprinodon bovinus. These include competition for territorial sites with the plains killifish (Fundulus zebrinus) (07); competition for food with both native and introduced species since almost all fishes inhabiting the Leon Creek drainage have exceedingly similar food habits (10); and severe limitations on available habitat due to declining ground water levels and spring flows (02,06,07,09,13). Little information is known concerning survival rates, longevity or population numbers (06), however, winter populations are suspected to be much higher than the minimum 0.11 individuals per square meter reported by Kennedy (07,10). SPECIES INTERRELATIONSHIPS: A number of other fishes occur in Leon Creek. These include: Cyprinus carpio (carp, introduced species), Notropis lutrensis (red shinner), Fundulus zebrinus (plains killifish), Lucania parva (rainwater killifish), Gambusia affinis (mosquitofish), G. nobilis (Pecos gambusia, an Endangered species), G. affinis x G. nobilis hybrids, G. geiseri (largespring gambusia, introduced species), Micropterus salmoides (largemouth bass), and Lepomis cyanellus (green sunfish) (02,06,07,08,09,10). OTHER LIFE HISTORY DESCRIPTORS: None. Life History - 2
                           (DRAFT) - Management Practices
                            Species PUPFISH, LEON SPRINGS
                                Species Id ESIS252009
                                   Date 14 MAR 96



MANAGEMENT PRACTICES

RESULT MANAGEMENT PRACTICE Beneficial Restricting/regulating human disturbance of populations Beneficial Maintaining/Controlling Water Flow Beneficial Developing/maintaining/protecting wetlands Beneficial Controlling water levels Beneficial Maintaining undisturbed/undeveloped areas Beneficial Restricting/regulating human use of habitats Beneficial Land Acquisition Beneficial Water Right Acquisition Beneficial Controlling pollution [thermal, chemical, physical] Beneficial Controlling/Restricting Pesticide Use Beneficial Controlling/Restricting Herbicide Use Beneficial Creating Artificial Habitat/Nesting Structure Beneficial Stocking captive-reared wild-strain animals Beneficial Controlling/Removing Exotic Vertebrates Adverse Hybridization Existing Hybridization Adverse Gas/Oil Development Existing Gas/Oil Development Adverse Recreational development Existing Recreational development Adverse Flooding Existing Flooding Adverse Groundwater drawdown Existing Groundwater drawdown Adverse Reservoirs Existing Reservoirs Adverse Irrigating Existing Irrigating Adverse Competition Existing Competition Adverse Exotic/Feral/Introducted Species Existing Exotic/Feral/Introducted Species Adverse Existing COMMENTS ON MANAGEMENT PRACTICES - One of the major factors for the present status of the Leon Springs pupfish is the loss of habitat in the area of the type locality, Leon Springs (06). In addition to the loss of the population at the type locality, four major threats may be associated with this species: 1) Habitat loss resulting from surface water reduction (as a consequence of development, especially agricultural). 2) Genetic contamination caused by hybridization with introduced Cyprinodon variegatus. 3) Loss of resources due to interference competition from introduced species. 4) The potential pollution and habitat alteration hazards Management Practices - 1 (DRAFT) - Management Practices Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 associated with a habitat within an active oil/natural gas field (06). It is presumed that the distribution of Cyprinodon bovinus extended from the Leon Springs downstream to the presently inhabited localities since Leon Springs once provided a flow of approximately 600 cubic liters of water per second (20 cf/s). Extensive irrigation caused an overdraft of the groundwater which caused the springs to essentially cease flowing by 1958 (08,09). Leon Springs were inundated by Lake Leon in 1918 (to be used for irrigation and fishing) and the Leon Springs pupfish was exterminated from the type locality by 1938 (05). The species was thought to be extinct until the downstream populations were discovered in 1965 by Minckley and Barber (01,05). Several limiting factors are known or suspected for Cyprinodon bovinus. These include competition for territorial sites with the plains killifish (Fundulus zebrinus) (07); competition for food with both native and introduced species since almost all fishes inhabiting the Leon Creek drainage have exceedingly similar food habits (10); and severe limitations on available habitat due to declining ground water levels and spring flows (02,06,07,09,13). The survival of C. bovinus depends on persistence of spring/ seep flows. It has been demonstrated that the mere existence of surface waters will not ensure survival of the species because it was extirpated from Leon Springs at a time when the Leon Springs/Lake Leon waters were at a maximum. Although the species is capable of achieving large population sizes in thermally unstable pools, these habitats would not persist if the springs were to fail. Furthermore, the springs may represent a last refugium should other fishes be introduced into the area. Cyprinodon bovinus might be better adapted to life in the spring environments of Leon Creek than would other species. However, some species, e.g., C. pecosensis and C. variegatus, probably are more competitive in thermally unstable situations. With respect to genetic contamination by introduced pupfishes, such springs might provide the appropriate environmental selection gradients to reduce introgression of the C. bovinus genome. Springs and seeps feeding the area presently occupied by C. bovinus apparently derive their flow from a saline aquifer that has been less affected by pumping of groundwater than have other springs in the vicinity of Leon Creek. A number of freshwater springs (less than or equal to 1 ppt.), some very large, have gone dry due to overdraft of groundwater, primarily for irrigation purposes (13,14). Presumably, Diamond Y Spring and associated springs have survived because the water is not desirable for most human uses. Brune (13) suggested that the flow in Diamond Y Spring is dependent on underground flow from Lake Leon, however, the exact source is unknown and needs investigation. Like other Cyprinodon, C. bovinus seems to exhibit little premating reproductive isolation when exposed to other pupfishes. In 1976, 2 years after C. variegatus was discovered in Leon Creek at the Highway 18 bridge, hybrids between C. bovinus and C. variegatus were very abundant in the lower watercourse. Although two specimens with C. variegatus characteristics were taken near the headpool of Diamond Y Spring, C. variegatus never became established in the Management Practices - 2 (DRAFT) - Management Practices Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 upstream watercourse. Preliminary experiments by P.V. Loiselle (pers. comm., in: 06) indicated that initial interbreeding in Leon Creek may have been facilitated by the "rare male" effect: In mate preference tests, females of C. bovinus actually choose males of a species from west of the Continental Divide, C. macularius, over conspecific males. However, similar tests by Garrett (1979) suggested that female C. bovinus are relatively indiscriminate between males of C. variegatus and C. bovinus. Therefore, C. bovinus clearly has weak premating isolation when exposed to C. variegatus. Presence of the hybrid swarm prompted an intensive effort to remove the introduced C. variegatus genome from the downstream watercourse, an action that apparently was successful (09). The lesson from the release of C. variegatus into Leon Creek is clear---introduced Cyprinodon pose a very serious threat to the survival and integrity of the C. bovinus genome. Because C. bovinus apparently has broad ecological needs, almost any co-occurring species of fish, either indigenous or introduced, represents a potential competitive threat. Most desert fishes live in waters with few associated natives. However, competition with introduced congeners poses an especially serious problem. Most species of Cyprinodon occur in isolation from other members of the genus. For example, the three native Cyprinodon in the Pecos River are physically isolated from each other and never have been taken together, although in wetter periods (e.g., Pleistocene) there would have been opportunities for contact through the Pecos River. This suggests that two-species assemblages of Cyprinodon are unstable and that when species occur together one is excluded by the other. Like C. bovinus, the Pecos pupfish, C. pecosensis occurs in saline waters. Therefore, C. pecosensis probably is a more serious threat to C. bovinus than C. elegans, a species of the Pecos drainage known only from freshwaters. C. variegatus is another species which does well in saline waters, but pure specimens of this introduced species never became abundant in Leon Creek. It appears that hybridization/genetic contamination by C. variegatus was a more serious threat than competition. APPROVED PLAN: U.S. Fish and Wildlife Service. 1985. Leon Springs Pupfish Recovery Plan. Prepared by the Rio Grande Fishes Recovery Team. U.S. Fish and Wildlife Service, Albuquerque, New Mexico. 26 pp. The prime objective of the Recovery Plan is to improve the status of the Leon Spring pupfish to the point that survival is secured and viable populations of all morphotypes are maintained in the wild. To properly maintain natural populations, more information on the ecological needs of the Leon Spring Pupfish is needed, including information on: 1) Competition with coexisting species. 2) Reproductive variables. 3) Predation by other species. 4) Survivorship. 5) Diseases and parasites. 6) Impacts of exotics. Management Practices - 3 (DRAFT) - Management Practices Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 7) Effects of seasonal changes in stream flows. 8) Distribution and abundance of the pupfish within the two remaining occupied habitats on the Leon Creek in relation to other fishes. 9) Chemical and physical characteristics of the habitat and other extraneous factors. Management of the pupfish habitat should include the following: 1) Continued cooperation with the local landowners, Texas Parks and Wildlife, and local oil and gas companies in order to protect pupfish habitat (i.e., either water right or land acquisition or both). 2) Protection of important springs against inadvertent spillage of oil field effluents using earthen dikes. 3) Erecting signs at access points to occupied and potential (Lake Leon) habitat warning against introductions of exotic fish (i.e., bait fish) into the system. Limiting human access may be another alternative. 4) Production of a management plan to include emergency actions in case of spring failure. For example: using wells to supplement or simulate spring flow; construction of off site refugium canals or pools; monitoring procedures and alternative natural sites for reintroduction. 5) Monitoring of existing populations twice yearly. The captive population of the Leon Spring Pupfish at Dexter NFH should be maintained for scientific research and as a reserve gene pool in the event that the wild population experiences a severe decline. The pupfish should be reintroduced into Lake Leon after a study of environmental conditions is conducted there. The Leon Spring Pupfish should be provided the full protection mandated by Federal and Texas laws. Finally, public awareness of the uniqueness of the pupfish should be increased through the preparation of information pamphlets, interpretive programs, and a motion picture on its uniqueness and the Endangered status of the entire aquatic ecosystem. Although not mentioned in the Recovery Plan it may be desirable to reduce competition and the risk of hybridization by removing introduced exotic fish. Considering the surrounding agriculture and the use of irrigation it may also be helpful to control herbicides and pesticides that are known to be harmful to the food chain on which the pupfish depends. Land use zoning and the controlling of pollutants from the oil development in the area may in fact help maintain the water table and aid in the management of local wetlands and water flows. Oil and gas drilling (development) may also be an activity in need of some monitoring in relation to pollutants and disturbance of the water table. U.S. Fish and Wildlife Service personnel at Dexter National Fish Hatchery, Dexter, NM, are successfully maintaining a large, captive population of C. bovinus. Northern Natural Gas Company, Exxon Company, and other oil/gas concerns operate in the vicinity of Leon Creek and are cautious to avoid adverse impacts on the area. The Trans-Pecos Soil and Water Conservation District, in cooperation with the Soil Conservation Service, constructed a protective dike around the headpool of Diamond Y Spring to ensure that an oil spill will not reach this habitat. Management Practices - 4 (DRAFT) - Management Practices Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 This and other conservation efforts have been greatly facilitated by the concern and hospitality of the landowners. Between February 1976 and August 1978, intensive rotenone and seining operations were conducted for the purpose of eradicating the introduced C. variegatus genome from Leon Creek downstream from Diamond Y Spring. Management Practices - 5
                                   (DRAFT) - References
                              Species PUPFISH, LEON SPRINGS
                                  Species Id ESIS252009
                                      Date 14 MAR 96



     

References

***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE ***** 01 Baird and Girard. 1853. Descriptions of new species of fishes collected by Mr. John H. Clark, on the U.S. and Mexican Boundry Survey, under Lt. Col. Jas. D. Graham. Proc. Acad. Nat. Sci. Phila. (1852-1853) 6:387-390. 02 Echelle, A.A. and R.R. Miller. 1974. Rediscovery and redescription of the Leon Springs pupfish, Cyprinodon bovinus, from Pecos County, Texas. Southwest. Nat. 19:179-190. 03 Echelle, A.A. and C. Hubbs. 1978. Haven for Endangered pupfish. Texas Parks and Wildlife Mag. 36:9-12. 04 Echelle, A.A. and A.F. Echelle. 1978. The Pecos River pupfish, Cyprinodon pecosensis n, sp. (Cyprinodontidae), with comments on its evolutionary origin. Copeia 1978:569-582. 05 Williams, J.G. 1981. Electrophoretic variation among nine species of the genus Cyprinodon (Cyprinodontidae). Unpubl. Ph.D. Diss., The Univ. of Texas, Austin. 06 U.S. Fish and Wildlife Service. 1985. Leon Springs Pupfish Recovery Plan. Prepared by the Rio Grande Fishes Recovery Team. U.S. Fish and Wildlife Service, Albuquerque, New Mexico. 26 pp. 07 Kennedy, S.E. 1977. Life history of the Leon Springs pupfish, Cyprinodon bovinus. Copeia 1977:93-103. 08 Echelle, A.A. and A.F. Echelle. 1980. Status of the Pecos gambusia (Gambusia nobilis). U.S. Fish and Wildlife Service, Albuquerque, NM. Endangered Species Rept. No. 10. 73 pp. 09 Hubbs, C. 1980. The solution to the Cyprinodon bovinus problem: eradication of a pupfish genome. Proc. Desert Fishes Council 10:9-18. 10 Hubbs, C., T. Lucier, E. Marsh, G.P. Garrett, R.J. Edwards and E. Milstead. 1978. Results of an eradication program on the ecological relationship of fishes in Leon Creek, Texas. Southwest. Nat. 23:487-496. 11 Minckley, W.L. and E.T. Arnold. 1969. "Pit digging", a behavioral adaptation in pupfishes (genus Cyprinodon). J. Ariz. Acad. Sci. 5:254-257. 12 Garrett, G.P. 1980. Species specificity in the mating systems of Cyprinodon variegatus and Cyprinodon bovinus. Proc. Desert Fishes Council 11:54-59. 13 Brune, G. 1981. Springs of Texas. Vol. 1. Branch-Smith, Inc., Fort Worth, Texas. 14 Scudday, J.F. 1978. Some recent changes in the herpetofauna of the northern Chihuahuan Desert. Pp. 513-522. In: Transactions of the Symposium on the Biological Resources of the Chihuahuan Desert Region, United States and Mexico. Wauer and Riskind, eds. NPS Trans. and Proceed. Ser. No. 3. ***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY ***** 01 Echelle, A.A. and R.R. Miller. 1974. Rediscovery and redescription of the Leon Springs pupfish, Cyprinodon bovinus, References - 1 (DRAFT) - References Species PUPFISH, LEON SPRINGS Species Id ESIS252009 Date 14 MAR 96 from Pecos County, Texas. Southwest. Nat. 19:179-190. 02 Kennedy, S.E. 1977. Life history of the Leon Springs pupfish, Cyprinodon bovinus. Copeia 1977:93-103. 03 Hubbs, C., T. Lucier, E. Marsh, G.P. Garrett, R.J. Edwards and E. Milstead. 1978. Results of an eradication program on the ecological relationship of fishes in Leon Creek, Texas. Southwest. Nat. 23:487-496. 04 Echelle, A.A. and A.F. Echelle. 1980. Status of the Pecos gambusia (Gambusia nobilis). U.S. Fish and Wildlife Service, Albuquerque, NM. Endangered Species Rept. No. 10. 73 pp. 05 U.S. Fish and Wildlife Service. 1985. Leon Springs Pupfish Recovery Plan. Prepared by the Rio Grande Fishes Recovery Team. U.S. Fish and Wildlife Service, Albuquerque, New Mexico. 26 pp. 06 Baird and Girard. 1853. Descriptions of new species of fishes collected by Mr. John H. Clark, on the U.S. and Mexican Boundry Survey, under Lt. Col. Jas. D. Graham. Proc. Acad. Nat. Sci. Phila. (1852-1853) 6:387-390. 07 Girard, C. 1859. Ichthyology of the boundary. In: United States and Mexican Boundary Survey, under the order of Lt. Col. W.H. Emory. Vol. 2. 88 pp. + 41pl. 08 Scudday, J.F. 1978. Some recent changes in the herpetofauna of the northern Chihuahuan Desert. Pp. 513-522. In: Transactions of the Symposium on the Biological Resources of the Chihuahuan Desert Region, United States and Mexico. Wauer and Riskind, eds. NPS Trans. and Proceed. Ser. No. 3. 09 Brune, G. 1981. Springs of Texas. Vol. 1. Branch-Smith, Inc., Fort Worth, Texas. References - 2