The Extinction of the Catarina Pupfish Megupsilon Aporus and the Implications for the Conservation of Freshwater Fish in Mexico

The extinction of the Catarina pupfish Megupsilon aporus and the implications for the conservation of freshwater fish in Mexico

A RCADIO V ALDÉS G ONZÁLEZ,LOURDES M ARTÍNEZ E STÉVEZ M A .ELENA Á NGELES V ILLEDA and G ERARDO C EBALLOS

Abstract Extinctions are occurring at an unprecedented ; Régnier et al., ). Since the start of the st century it rate as a consequence of human activities. Vertebrates con- has become clear that population depletion and extinction stitute the best-known group of animals, and thus the group of both freshwater and marine fishes is a severe and wide- for which there are more accurate estimates of extinctions. spread problem (e.g. Ricciardi & Rasmussen, ; Myers Among them, freshwater fishes are particularly threatened &Worm,; Olden et al., ; Burkhead, ). and many species are declining. Here we report the extinc- Extinction of freshwater fishes has been relatively well tion of an endemic freshwater fish of Mexico, the Catarina documented in North America (e.g. Miller et al., ; pupfish Megupsilon aporus, the sole species of the genus Burkhead, ). A compilation of the conservation status Megupsilon. We present a synopsis of the discovery and de- of freshwater fishes in Mexico has revealed that  species scription of the species, the threats to, and degradation of, its have become extinct in the wild or have been extirpated habitat, and the efforts to maintain the species in captivity from the country, and .  (% of all species in before it became extinct in . The loss of the Catarina Mexico) are facing extinction (IUCN, ; Ceballos et al., pupfish has evolutionary and ecological implications, and b; Table ). highlights the crisis of freshwater fish extinctions. It is a While compiling these data we found that the Catarina warning of the likely fate of more than  freshwater fish pupfish Megupsilon aporus is the most recently extinct en- species threatened with extinction in Mexico. To save these demic freshwater fish in Mexico. This species, which be- species, the country urgently needs a national strategy to ar- longs to the Cyprinodontidae and is one of the smallest ticulate a bold conservation effort, with better policies on fishes in North America, was lost as a result of desiccation ecosystem management and water use. of the only freshwater spring it inhabited, in El Potosi, Galeana, Nuevo León (Miller et al., ; Bennett & Keywords Catarina pupfish, conservation, Cyprinodontidae, Conway, ). Unfortunately, this is not an isolated case. extinction, fish, Megupsilon aporus,Mexico Major threats to freshwater fishes in particular and freshwater biodiversity in general have been grouped into five categories: overexploitation of water resources, water pollu- Introduction tion, flow modification, destruction or degradation of habitat, and invasive species (Silk & Ciruna, ; Dudgeon iodiversity loss is one of the most severe environmental et al., ). Inland waters in Mexico have experienced Bproblems, with thousands of species having gone ex- these threats, and currently % of main rivers are polluted,  tinct since the start of the th century and hundreds of . , dams have modified their flow and .  invasive thousands of populations being lost as a result of human ac- species inhabit inland waters (Carabias & Landa, ;  tivities (Ceballos et al., a). The rate of extinction of ver- Domínguez-Domínguez et al., ; CONAGUA, ).  tebrate species in this period has been up to times faster The effect of these threats on freshwater fishes depends   than in the last million years (Ceballos et al., ). on the particular environmental conditions, the type and Extinctions of birds and mammals have been documented amount of pressure exerted by human activities, and the more thoroughly than extinctions of fishes and inverte- distribution range of species. For instance, species with re- brates, which have often been overlooked (e.g. Dirzo et al., stricted distributions, such as the Cuatro Cienegas platyfish Xiphophorus gordoni, which inhabits desert springs, and the Yucatan tetra Astyanax altior, endemic to cenotes in the ARCADIO VALDÉS GONZÁLEZ and MA.ELENA ÁNGELES VILLEDA Universidad Autónoma de Nuevo León, Nuevo León, Mexico Yucatan Peninsula, are more imperilled than those with a  LOURDES MARTÍNEZ ESTÉVEZ (Corresponding author) Department of Ecology and wide distribution (Jelks et al., ; Contreras-MacBeath Evolutionary Biology, University of California, 115 McAllister Way, Santa Cruz, et al., ). Meanwhile, habitats in northern Mexico with California 95060, USA. E-mail [email protected] major water supply problems as a result of semi-arid and GERARDO CEBALLOS Universidad Nacional Autónoma de México, Mexico City, arid conditions are at higher risk of desiccation than Mexico aquatic systems in south-east Mexico (Contreras-Balderas Received  September . Revision requested  November .   Accepted  April . First published online  December . & Lozano-Vilano, ; Carabias & Landa, ; Ceballos

Oryx, 2020, 54(2), 154–160 © 2018 Fauna & Flora International doi:10.1017/S003060531800056X Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.229, on 25 Sep 2021 at 23:58:58, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S003060531800056X Extinction of the Catarina pupfish 155

TABLE 1 Freshwater fish species that are extinct in the wild or extirpated in Mexico (Ceballos et al., b).

Species Distribution Status Cyprinodon alvarezi Mexico, endemic Extinct in the wild Cyprinodon longidorsalis Mexico, endemic Extinct in the wild Cyprinodon veronicae Mexico, endemic Extinct in the wild Skiffia francesae Mexico, endemic Extinct in the wild Xyrauchen texanus North America Extirpated Gila elegans North America Extirpated Hybognathus amarus North America Extirpated Notropis simus North America Extirpated Ptychocheilus lucius North America Extirpated Rhinichthys osculus North America Extirpated

et al., a,b). Watershed management in Mexico therefore requires addressing local conservation issues with a regional PLATE 1 The Catarina pupfish Megupsilon aporus was a freshwater fish endemic to Mexico; it is now extinct: (a) male, perspective, to ensure the maintenance of these habitats and (b) female. Photograph by Daniel Garza Tobón. their fish populations in the long term (Stiassny & Bianco, ; Ceballos et al., b). The Catarina pupfish (Plate ) was discovered in .It the dorsal fin in females, and particular behavioural traits was described in  as the only species of the genus (see below; Uyeno & Miller, ; Miller & Walters, ). Megupsilon, and only  years after its scientific discovery The small Catarina pupfish exhibited sexual dimorph- it became extinct in the wild. We present a historical synop- ism. Males were smaller ( mm in length) than females sis of the species and the causes of its decline, and discuss the ( mm; Miller & Walters, ). Adult males were steel implications of the extinction process for the conservation blue on the back and sides of the body, with a golden of freshwater fish diversity in Mexico. sheen in the caudal peduncle, the caudal fin was orange, and a there was a vertical black bar above and below the pupil on the eyes. Adult females had a golden olivaceous col- ouration over the body (Miller & Walters, ). The discovery and description of a new species

Available information on the biology and ecology of the Habitat Catarina pupfish is scarce but examination of peer-reviewed and grey literature provided us with sufficient details to docu- The Catarina pupfish was endemic to a freshwater spring at ment the sequence of events and factors that led to the El Potosi, on the west side of Sierra Madre Oriental, and with- species’ decline (Miller & Walters, ; Contreras-Balderas in the Sandia basin, Galeana, Nuevo León, Mexico (°′N & Lozano-Vilano, a,b; Contreras-Balderas et al., ; °′W; Fig. ). This location, at , m, was also home to Echelle et al., ; Jelks, et al., ;Bennett&Conway, the Potosi pupfish Cyprinodon alvarezi and the fresh- ;Burkhead,; Liu & Echelle, ). water crayfish Cambarellus alvarezi (Rodríguez-Almaraz & The first recorded individual of the Catarina pupfish was Campos, ), both also endemic to this small spring. The collected from the wild by R.R. Miller and H.L. Huddle in spring was a remnant of a larger water body in an endorheic , but the species was not described until  (Miller & basin known as La Hediondilla (Miller & Walters, ). It is Walters, ). Megupsilon aporus is an endemic Mexican believed that during the Pleistocene the larger lake was con- species (Miller, ). The generic name and species were nected with the Rio Conchos basin and Rio Bravo tributaries assigned based on two particular characters: Megupsilon in in the north. reference to the huge Y chromosome in males, and aporus in Habitat descriptions by Miller & Walters () men- reference to the lack of pores in the cephalic sensory system tioned the presence of a main pond (c.  ha) with an inner (Miller & Walters, ). Although the species is related to stream and some secondary ponds. Clear water was present Cyprinodon, the characters that classified it as a separate spe- year-round, with depths of .– m (Miller & Walters, cies, along with those previously mentioned, were a different ). These conditions remained until the early s number of chromosomes between males () and females (Plate ; Rodriguez-Almaraz & Campos, ). The vegeta- (), the presence of side scales between the dorsal and tion in the area included pennywort Hydrocotyle sp., anal fins, the lack of a black terminal border in the anal herbaceous flowering plants Nasturtium sp., water fin of nuptial males, the presence of an anal fin as large as primrose Lugwigia sp., hornwort Ceratophyllum demersum,

FIG. 1 Location of El Potosi spring in Nuevo León, Mexico, which is the only known habitat of the Catarina pupfish Megupsilon aporus.

pondweed Potamogeton sp., duckweed Lemna sp., green algae, and grasses restricted to shallow areas (Miller & Walters, ; Guzmán-Cedillo, ).

PLATE 2 Habitat degradation and desiccation of the El Potosi   Natural history and ecology spring in Nuevo León, Mexico (Fig. ). (a) The spring in (photograph from Miller et al., ), and (b) in  Megupsilon aporus was considered to be part of a relict fauna (photograph by María Elena Ángeles Villeda). isolated from the Rio Grande system more than  million years ago (Echelle et al., ). It diverged from the common Cyprinodon ancestor to constitute a monotypic genus in the late Miocene (Echelle et al., ). Following its discovery, and there was no cannibalistic egg consumption nor aggres- several expeditions were made to gather information on sion of any kind among males and females (V. González, the species and its habitat (Table ). On an expedition in pers. comm.).   Contreras-Balderas and Lozano-Vilano found that the According to Miller & Walters ( ), M. aporus coex- flow in the pond was constant year-round and that aquatic isted with the Potosi pupfish via niche partitioning. The vegetation was abundant. They also described the abundance Catarina pupfish preferred shallow areas close to the surface, of M. aporus;c., individuals were found in pockets whereas the Potosi pupfish occurred predominantly in the of the aquatic vegetation mat, which was mainly composed deep waters of the spring. The two species had different diet- of Ceratophyllum sp. (Contreras-Balderas & Lozano-Vilano, ary preferences; the Catarina pupfish was carnivorous, feed- a). By , individuals of largemouth bass Micropterus ing mainly on insect larvae and chironomids, whereas the salmoides were collected in El Potosi and the abundance of Potosi pupfish fed mainly on algae. Megupsilon was significantly lower. There is no information regarding the introduction of this exotic fish but its presence was one of the causes of the decline of the Catarina pupfish, Habitat degradation although not the most pervasive (Contreras-Balderas & Lozano-Vilano, a; see below). The habitat, described by Miller & Walters (), remained The Catarina pupfish was oviparous, with no breeding in good condition for more than  years (Rodríguez-Almaraz territoriality. The species presented two characteristic beha- & Campos, ). During – the area covered by the viours: opercular rotation and jaw-nudging during court- spring contracted and expanded as a result of water extraction ship (Liu & Echelle, ). Courtship and mating took a for agriculture and subsequent recovery during the wet sea- unique form, with no aggressive behaviour; instead attrac- son. However, in  the spring was reduced to %ofits tive movements were performed to bring about successful former size as a result of intensified groundwater pumping. spawning. Mating was usually carried out at dawn or dusk By  only a shallow irrigation ditch and small tributaries

TABLE 2 Details of expeditions to the El Potosi spring in Nuevo León, Mexico (Fig. ), the only known habitat of the Catarina pupfish Megupsilon aporus (Contreras-Balderas, ; Rodríguez-Almaraz & Campos, ; Contreras-Balderas & Lozano-Vilano, a).

Date Lead scientists Comments Feb. 1961 R.R. Miller & H.L. Huddle Specimen of Megupsilon aporus found Feb. 1968 V. Walters & J. Bleck 510 individuals of M. aporus collected Mar. 1968 R.R. Miller & H.L. Huddle Holotypes of M. aporus collected June 1968 V. Walters & B.J. Turner 151 individuals of M. aporus collected 1968 S. Contreras-Balderas & M.L. Lozano-Vilano Circa 6,000 individuals of M. aporus reported July 1972 V. Walters, R.E. Brown Jr., R. Haas, R.K. Liu & High abundance of M. aporus reported S.H. Walters 1974 S. Contreras-Balderas Collection of largemouth bass Micropterus salmoides, reported as common species 1974 S. Contreras-Balderas Translocation of individuals of M. aporus to adjacent springs without largemouth bass Late 1970s & early G.A. Rodriguez-Almaraz & E. Campos Contraction of the spring as a result of intensified groundwater 1980s pumping Early 1990s S. Contreras-Balderas Overexploitation of water for crop irrigation 1994 S. Contreras-Balderas M. aporus considered extinct in the wild 1995 S. Contreras-Balderas Desiccation of El Potosi spring

remained (Contreras-Balderas & Lozano-Vilano, a; & Lozano-Vilano, a). One year later, a small population Plate ). of M. aporus was identified in a small spring in the area. In Overexploitation of water was the main cause of the de-  Armando J. Contreras-Balderas and his team eradicated cline of M. aporus (Contreras-Balderas & Lozano-Vilano, the largemouth bass, removing .  individuals from the a). By  more than  wells of .  m depth had spring (Contreras-Balderas & Lozano-Vilano, a). In the been dug for irrigation of corn and potato fields in El following years, the rapid degradation of the habitat as a result Potosi and Sandia Valleys, causing the desiccation of springs of water extraction increased the need to maintain the species and creeks in the region. As a result, aquatic species, includ- in captivity to avoid extinction. Since  the Catarina pup- ing the fishes Cyprinodon veronicae, Cyprinodon longidorsa- fish remained in captivity in a management unit specifically lis, Cyprinodon ceciliae and Cyprinodon inmemoriam for the conservation of the species. became locally extinct (Contreras-Balderas, ). The In the early s the New York Aquarium and Catarina pupfish was considered to be extinct in the wild Universidad Autonoma de Nuevo León established a pro- by , and in  El Potosi spring was completely dry gramme (Emerging rescue of Mexican fish species in immi- (Tveteraas, ; Contreras-Balderas & Lozano-Vilano, nent danger of extinction) to protect the most representative b). and threatened freshwater fishes of Mexico. The effort was Given the grave situation, a strategic plan to protect the also joined by the Children’s Aquarium at Fair Park, Dallas, area was presented by the first Mexican fish recovery team, Texas. The aims of the programme were to sustain stocks of which comprised researchers from Universidad Autonoma species over the long term, to maintain sufficient individuals de Nuevo León. However, the proposal was not adopted or to repopulate native habitats, and to exchange specimens to enforced (Contreras-Balderas, ). ensure the diversity of the genetic pools, all by recruiting In the early s natural coal deposits in the area started museums and public aquariums with sufficient space and burning as a result of the collapse and subsidence of sedi- technical and economic resources. ments, causing the ground to sink in both the El Potosi Individuals of the Catarina pupfish were maintained in and La Sandia valleys. Burning episodes have been intermit- various places, including San Luis Potosi in Mexico, tent, with wet and dry periods (Valdés González, ; Denver and Arkansas in the USA, Zaragoza in Spain, and Amezcua Torres, ). Germany. However, the species was particularly sensitive to environmental conditions and prone to infections. In  most individuals of the captive populations succumbed Captivity and extinction to Mycobacteria infections and those that remained were too weak or sterile. One of the first attempts to protect the Catarina pupfish was In  the Children’s Aquarium at Fair Park, Dallas, made by Salvador Contreras-Balderas, who in  moved nu- Texas, held the last surviving population, with only  indi- merous individuals to other springs in the area to reduce the viduals (Liu & Echelle, ). The last two males were used pressure exerted by the largemouth bass (Contreras-Balderas in an attempt to save the species through hybridization and

TABLE 3 Freshwater fish species endemic to Mexico or Mexico and the USA that are now extinct, with former geographical location, and causes of extinction (Burkhead, ; Ceballos et al., b).

Species Distribution Geographical location Cause of extinction (estimated year) Atherinella callida Mexico Rio Tonto drainage, Veracruz Pollution (1957) Chirostoma bartoni Mexico Crater lake at Valle de Santiago, Guanajuato Desiccation (2006) Chirostoma charari Mexico La Mintzita spring, Morelia Habitat degradation (1957) Evarra bustamantei Mexico Xochimilco, Mexico City Habitat degradation; pollution (1983) Evarra eigenmanni Mexico Chalco/Xochimilco, Mexico City Habitat degradation; pollution (1983) Evarra tlahuacensis Mexico Chalco, Mexico City Habitat degradation; pollution (1983) Notropis aulidion Mexico Tunal River, Durango Invasive species (1965) Notropis orca North America Rio Grande, USA/Mexico Invasive species (1975) Notropis saladonis Mexico Salado River, Nuevo León, Coahuila Unresolved (1992) Stypodon signifer Mexico Spring, Parras Coahuila Desiccation (1930) Cyprinodon ceciliae Mexico La Presa Spring, Nuevo León Desiccation (1991) Cyprinodon inmemoriam Mexico Ojo la Trinidad, Nuevo León Desiccation (1986) Cyprinodon latifasciatus Mexico Parras, Coahuila Pollution (1930) Megupsilon aporus Mexico Spring, El Potosi, Nuevo León Desiccation/invasive species (2014) Characodon garmani Mexico Spring, Parras Coahuila Desiccation/pollution (1900) Priapella bonita Mexico El Refugio, Veracruz Pollution (1906)

backcross with a female of C. alvarezi. The reproduction was became extinct were vulnerable, microendemic species successful, yielding more than  newborn individuals; whose life histories were adapted to isolated environments however, all of them were females with mycobacteriosis, and particular conditions. However, the increasing pressure and all eventually died. on freshwater resources may cause a generalized extinction trend, affecting even widely distributed species. Lessons learned Concern for Mexican freshwater fishes has led to an increase in knowledge about this group and the habitats on The extinction of the Catarina pupfish has implications at which they depend. For instance, in  a national-level various scales. Megupsilon aporus was a monotypic genus analysis of the gaps in the conservation of aquatic biodiver- that diverged from Cyprinodon c.  million years ago ac- sity in Mexico was published (Aguilar et al., ). This ef- cording to molecular analyses (Echelle et al., ). The fort, which involved more than  specialists, resulted in loss of this species precludes any opportunity to study its the identification of priority sites and their representative- unique evolutionary history and to understand the adaptive ness in the national system of protected areas. Although processes by which it was able to survive as a relic for thou- the results indicated that only .% of the area covered by sands of years. Its extinction, as suggested by Burkhead priority sites is currently protected, it was a first step to in- () for freshwater fishes in general, is evidence of a crease action focused on the conservation, management and much larger problem: the current loss of freshwater restoration of aquatic systems in Mexico. biodiversity. In  Mexico included  freshwater fishes as part of the Freshwater fishes are being lost at a faster rate than ter- Alliance for Zero Extinction, an international initiative to restrial species. Jelks et al. () reported  imperilled safeguard places with microendemic species (AZE, ). freshwater fishes in North America; of the  species cate- Local efforts to protect the species and their habitats have gorized as Endangered,  are endemic to Mexico (Jelks et al. increased awareness among the population. For instance, ; Burkhead, ). In the th century Mexico has lost  the designation of the RAMSAR site Manantiales geoter- species,  of them endemic (IUCN, ; Ceballos et al., males de Julimes, in , was supported by the presence of a,b; Table ). The extinction of these species is attribu- the Julimes pupfish Cyprinodon julimes. This killifish was ted to two main causes: habitat degradation and pollution. described in  and its distribution is limited to El Habitat degradation by desiccation of water bodies affected Pandeño hot spring in Chihuahua, Mexico (De la species that inhabited springs in arid and semi-arid environ- Maza-Benignos & Vela-Valladares, ). The local commu- ments, which are under water stress as a result of low pre- nity, together with non-profit organizations, researchers and cipitation and a high demand for water for human activities the local government have developed a conservation strategy (De la Vega, ). Species that were affected by pollution for the area, which includes the establishment of a state park lived in environments close to large cities or to industries (Blando-Navarrete et al., ; De la Maza-Benignos, ). that discharge pollutants to the water without regulation Research conducted by Mexican academic institutions, or previous treatment (Alcocer, ). The species that sometimes in collaboration with international partners,

has increased the ex situ conservation efforts for imperilled AMEZCUA TORRES,N.() Caracterización de materia orgánica freshwater fishes. Universidad Michoacana de San Nicolas sedimentaria lacustre: un ejemplo del paleolago El Potosí, Nuevo León, México. Revista Geociencia, , –. de Hidalgo and Universidad Autonoma de Nuevo León   AZE (ALLIANCE FOR ZERO EXTINCTION)( ) Http://www. have led the efforts, with more than species kept in cap- zeroextinction.org [accessed  July ].  tivity (Lascuráin et al., ). In particular, the golden skiffia BENNETT, M.G. & CONWAY, K.W. () An overview of North Skiffia francesae and tequila splitfin Zoogoneticus tequila are America’s diminutive freshwater fish fauna. Ichthyological examples of species that otherwise would be extinct, as they Exploration of Freshwaters, , –. no longer exist in the wild (Lascuráin et al., ). BLANDO-NAVARRETE, J.L., JIMÉNEZ-GONZÁLEZ, J., VALENCIA- CASTRO, C.M., CASTAÑEDA-GAYTÁN,G.&CARRILLO-FLORES,R. There is still an urgent need to implement programmes () Estudio técnico justificativo para declarar Parque Estatal El focused on the maintenance of freshwater systems. Lack of Pandeño de los Pando, en el Municipio de Julimes Chihuahua. regulation and enforcement are threatening both freshwater Biodesert A.C., World Wildlife Fund, Universidad Juárez del estado fishes and water provision. The extinction of the Catarina de Durango, Universidad Autónoma Chapingo, México.  pupfish is a reminder of the vulnerability of aquatic systems. BURKHEAD, N.M. ( ) Extinction rates in North American freshwater fishes, –. BioScience, , –. There is a need to improve ecosystem management strate- CARABIAS,J.&LANDA,R.() Agua, medio ambiente y sociedad. gies and the policies related to freshwater resources, and Hacia la gestión integral de los recursos hídricos en México. UNAM, the development of a national strategy for the conservation El Colegio de México, Fundación Gonzalo Río Arronte, Ciudad de of freshwater fishes should be a priority. Such a strategy México, México. should include reintroduction of species extinct in the CEBALLOS, G., EHRLICH, P.R., BARNOSKY, A.D., GARCÍA, A., PRINGLE, R.M. & PALMER, T.M. () Accelerated modern wild, securing populations of the most threatened species human-induced species losses: entering the sixth mass extinction. both in captivity and in the wild, and reduction of threats. Science Advances, ,e. This strategy would bring together scientists and practi- CEBALLOS, G., EHRLICH, P.R. & DIRZO,R.(a) Biological tioners to identify species and priority sites for conservation, annihilation via the ongoing sixth mass extinction signaled by design a monitoring system to assess the current state of the vertebrate population losses and declines. Proceedings of the  populations, improve watershed management practices, and National Academy of Sciences of the United States of America, , E–E. increase the impact of ex situ and in situ conservation ac- CEBALLOS, G., DÍAZ-PARDO, E., MARTÍNEZ-ESTÉVEZ,L.&ESPINOSA tions to maintain species in the long term. A concurrent citi- PÉREZ,H.(b) Peces dulceacuícolas de México en peligro de zen science programme in which local communities would extinción. Fondo de Cultura Económica, Ciudad de México, México. play a main role in the protection and monitoring of the CONAGUA (COMISÍON NACIONAL DEL AGUA)() Informe habitats could have a positive impact, with relatively low Estadísticas del agua en México. Http://www.conagua.gob.mx/ CONAGUA/Publicaciones/Publicaciones/SGP---EAM. investment costs. There is still time to avert further pdf [accesed  March ]. extinctions of fish species in Mexico, but the window of CONTRERAS-BALDERAS,S.() Conservation of Mexican fresh water opportunity is closing. The next  decades will be critical fishes: some protected sites and species, and recent federal for most species at risk. legislation. In Battle Against Extinction. Native Fish Management in the American West (eds W.L. Minckley & J.E. Deacon), pp. –. The University of Arizona Press, Arizona, USA. Acknowledgements We thank the Instituto de Ecologia, CONTRERAS-BALDERAS,S.&LOZANO-VILANO, M.L. () Water, Universidad Nacional Autónoma de México, for support, and endangered fishes, and development perspectives in north-eastern Rosalba Becerra for preparing the figure. Mexico. Conservation Biology, , –. CONTRERAS-BALDERAS,S.&LOZANO-VILANO, M.L. (a) Survival Author contributions Conceptualization: GC; compilation of infor- status of the Sandia and Potosi Valleys endemic pupfishes and mation on the Catarina pupfish: AVG, MEAV, LME; writing: LME, GC. crayfishes from the Mexican plateau in Nuevo León, Mexico, with comments on extinct snails. Proceedings of the Desert Fishes Council, Volume XXVII,  Annual Symposium, . Conflicts of interest None. CONTRERAS-BALDERAS,S.&LOZANO-VILANO, M.L. (b) Extinction of most Sandia and Potosí valleys (Nuevo León, México) endemic pupfishes, crayfishes and snails. Ichthyological Exploration Ethical standards This research complied with the Oryx Code of of Freshwaters, , –. Conduct for authors. CONTRERAS-BALDERAS, S., ALMADA-VILLELA, P., LOZANO-VILANO, M.L. & GARCÍA-RAMÍREZ, M.E. () Freshwater fish at risk or References extinct in México. A checklist and review. Reviews in Fish Biology and Fisheries, , –. 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