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Overview

Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Range includes the Rio Grande watershed of Texas and northeastern Mexico from Brownsville northward to Brewster County, Texas (Bailey et al. 2005), and the Pecos River drainage of northwestern Texas (Culberson, Reeves, and Loving counties) and southeastern New Mexico, north to Brantley Reservoir (Ernst 1990, Degenhardt et al. 1996). Occurrences in Mexico are known from Coahuila, central Nuevo Leon, and northeastern Tamaulipas (Ernst 1990). In August 2007, Farr photographed individuals 0.5-4 km south of the river near Ciudad Miguel Alemán, Mexico, across from Roma, Texas (Bailey et al. 2008). Elevational range extends from sea level to around 1,100 meters (900-1,100 meters in New Mexico) (Degenhardt and Christiansen 1990, Degenhardt et al. 1996).

A 1998 record also exists for Menard County, Texas, about 170 km northeast of the nearest previously documented locality (Franklin and Reams 2001). This was an adult male found on the shoulder of a road, so additional study is needed to determine whether this record represents an established population or a translocated individual.

A specimen from "Blue Springs" in Eddy County, New Mexico, probably came from the Black River, a tributary of the Pecos River (Legler 1958).

Bailey et al. (2008) found P. gorzugi at low density and with a significant hiatus in the middle reaches of the Pecos River from the New Mexico border southward to the confluence with Independence Creek in Terrell County. Bailey et al. (2008) and W. Farr (Houston Zoo) were unable to locate individuals in the main channel of the Rio Grande south of Roma, Texas.

A sketchy record from the Bitter Lakes National Wildlife Refuge, Chaves County, New Mexico (Bundy 1951), may be erroneous; Degenhardt et al. (1996) questioned the identification (no specimen is known to exist), and recent searches for the species there have been unsuccessful.

See Ernst and Lovich (2009) for a recent map of the known distribution.

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Continent: North-America Middle-America
Distribution: Mexico ((Chihuahua, Coahuila, Nuevo Leon, Tamaulipas), USA (isolated populations in S New Mexico and adjacent Texas)  
Type locality: 3 1/2 mi. W Jimenez, Río San Diego, Coahuila, México, 850 feet [elevation].
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Physical Description

Size

Length: 37 cm

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Diagnostic Description

Pseudemys gorzugi differs from Chrysemys picta in lacking an ornately marked plastron (lower shell). It differs from Pseudemys texana in lacking a median notch often flanked by toothlike cusps on the upper jaw, and by lacking a red-tinged rim on the plastron. It differs from Trachemys scripta in lacking a prominent orange patch on each side of the head. It differs from Pseudemys concinna by having black and yellow concentric circles on the plastron instead of "C" markings (Degenhardt et al. 1996, Ernst and Lovich 2009).

Degenhardt et al. (1996) included a key to the turtles of New Mexico. Dixon (2000) presented a key to Texas turtle species.

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Type Information

Paratype; Paratype for Pseudemys gorzugi
Catalog Number: USNM 76
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Cadereyta, Nuevo Leon, Mexico
  • Paratype: Baur, G. 1893. Proc. Amer. Philos. Soc. 31: 223.; Paratype: Ward, J. P. 1984. Special Publications, The Museum, Texas Tech University. 21: 29, figure 6.
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Paratype; Paratype for Pseudemys gorzugi
Catalog Number: USNM 80
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Guadalupe Mountains, Locality In Multiple Counties, Texas, United States, North America
  • Paratype: Baur, G. 1893. Proc. Amer. Philos. Soc. 31: 223.; Paratype: Ward, J. P. 1984. Special Publications, The Museum, Texas Tech University. 21: 29, figure 6.
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Ecology

Habitat

Comments: Habitat includes rivers and their more permanent tributary streams (Garrett and Barker 1987), particularly larger, deeper stream pools with relatively clear water and sandy or rocky bottoms (Degenhardt and Christiansen 1990, Degenhardt et al. 1996). Occupied waters may have a muddy, sandy, or rocky bottom, and may or may not contain aquatic vegetation (Degenhardt et al. 1996). Degenhardt et al. (1996) reported a single, verified sight record for Willow Lake near Malaga, New Mexico. This species has been reported from the Bitter Lakes National Wildlife Refuge in Chaves County, New Mexico (Bundy 1951), where habitat consists of turbid ponds with soft, muddy bottoms, but Degenhardt et al. (1996) questioned the identification (no specimen from this locality was found). Individuals often bask on logs, overhanging vegetation, or muddy banks, or at the water's surface (Degenhardt et al. 1996). Eggs are buried in soil near water.

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Habitat and Ecology

Habitat and Ecology

Restricted to the mainstream of the Pecos and Rio Grande, and the lowermost few miles of tributaries (Ward 1984). Occurs as high as 1,082 m altitude in New Mexico (Degenhardt and Christiansen, in Ernst et al. 1994). Apparently absent from the Texas side of the lower Rio Grande (Ward 1984).


Examined gut contents were entirely vegetarian (Legler, in Ernst and Lovich 2009), although the species has also been thought to be omnivorous (Degenhardt et al. 1996, Ernst and Lovich 2009).

Animals reach up to 37.2 cm carapace length (CL) (Ernst and Lovich 2009). Limited information is available on reproduction: a clutch size of nine eggs has been reported; whether females produce multiple clutches remains unknown. Age and size at maturity remain unrecorded.


Systems
  • Terrestrial
  • Freshwater
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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

These turtle are nonmigratory, although reproductive females move unknown distances between aquatic habitat and terrestrial nesting areas. Based on limited radio-tracking data, Degenhardt et al. (1996) regarded this species as rather sedentary; individuals tended to stay in the same small river reach; researchers recorded one movement of approximately 300 meters.

Dispersal characteristics are unknown.

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Trophic Strategy

Comments: Legler (1958) reported that a specimen from New Mexico contained "finely chopped vegetable matter." Degenhardt et al. (1996) mentioned that fecal material of recently captured individuals in New Mexico contained green algae and crayfish fragments. Probably this turtle is omnivorous (Degenhardt et al. 1996, Ernst and Lovich 2009).

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 6 - 20

Comments: Occurrences have not been delineated using consistent criteria, so the number of occurrences is uncertain. However, given that the distribution may not be continuous within the range, likely there are several to many distinct occurrences. The map in Degenhardt et al. (1996) suggests that populations in New Mexico comprise not more than 2-3 distinct occurrences. Dixon (2000) indicated records in 10 counties in Texas; Bailey et al. (2004, 2005) added two additional county records in Texas. Iverson (1992) mapped a few dozen collection sites that might represent at least 15-20 distinct occurrences.

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Global Abundance

2500 - 100,000 individuals

Comments: Total adult population size is unknown but undoubtedly exceeds 1,000 and likely exceeds 10,000. This species is apparently uncommon in its small range in New Mexico but common in suitable habitat in Texas (Bartlett and Bartlett 1999).

In a 97-km stretch of the Pecos River, Bailey et al. (2008) recorded 123 adults (1.3 per river-km) and 3 juveniles (0.3 per river-km); in a 35-km stretch of the Devils River, they recorded 68 adults (1.9 per river-km) and 3 juveniles (0.09 per river-km). These data are based on surveys done by canoe in the early 2000s. The methods section of this paper inconsistently states that the surveyed area was 36 km in the Pecos River and 12 km in the Devils River.

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General Ecology

This turtle is a habitual basker.

Other turtle species sharing the same habitat most often include Chrysemys picta, Trachemys scripta, Chelydra serpentina, and Apalone spinifera (Degenhardt et al. 1996).

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Life History and Behavior

Cyclicity

Comments: Activity occurs mostly during daylight hours (Degenhardt et al. 1996). Activity occurs primarily during the warmer months but may occur also during suitably warm conditions in the cooler parts of the year. For example, in New Mexico, Degenhardt et al. (1996) found this turtle active at water temperatures of 12 C in early December.

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Reproduction

The life cycle includes several basic stages, minimally including eggs, hatchlings, juveniles, and adults.

In New Mexico, destroyed nests and gravid females have been found in late May; one gravid female contained 9 eggs; recently emerged hatchlings were found in mid-April (these evidently overwintered in the nest), mid-August, and late October (Degenhardt et al. 1996).

Life-span data are unavailable, but undoubtedly some individuals live at least a few decades.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Pseudemys gorzugi

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N3 - Vulnerable

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NatureServe Conservation Status

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Small range in streams in the Rio Grande and Pecos river drainages in Texas, New Mexico, and Mexico; habitat has been degraded by dams, water diversion, invasive plants, pollution, and other factors; vulnerable to wanton killing and collection for the pet trade; locally common in some areas, relatively uncommon in other parts of the range; better information is needed on population size and trends.

Intrinsic Vulnerability: Highly to moderately vulnerable.

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IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2011

Assessor/s
van Dijk, P.P.

Reviewer/s
Horne, B.D., Mittermeier, R.A., Philippen, H.-D., Quinn, H.R., Rhodin, A.G.J., Shaffer, H.B. & Vogt, R.C

Contributor/s
Lavin, P., Hammerson, G.A. & Mendoza-Quijano, F.

Justification

Pseudemys gorzugi has a large extent of occurrence (along the Pecos-lower Rio Grande basin, from New Mexico, US to Tamaulipas, Mexico). However, the area of occupancy is much smaller (perhaps less than 2,000 km2). The habitat is declining due to pollution and water control and diversion along the length of the main river. The species is also collected for the pet trade, and the population may be declining as a direct result of this.

Pseudemys gorzugi is assessed as Near Threatened on the basis that it nearly meets Vulnerable under criterion B1. However, further research is urgent to determine whether a threatened status is appropriate for this species, based on reported population fragmentation and decline.

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Global Short Term Trend: Relatively stable to decline of 30%

Comments: Trend over the past 10 years or three generations is unknown but probably relatively stable or more likely slowly declining.

Global Long Term Trend: Relatively stable to decline of 50%

Comments: Declines apparently have occurred in New Mexico (Biota Information System of New Mexico; http://www.bison-m.org/booklet.aspx?id=030010).

Dixon (2000) reported that this species "has disappeared completely from San Felipe Springs and its run in Del Rio" (Texas); the turtle was abundant in the outflow of the springs in 1996 (Forstner observations, cited by Dixon (2000).

Bailey et al. (2008) noted a conspicuous scarcity of juveniles in Texas but not in New Mexico. They cautioned that poor recruitment "could pose a serious threat to stability of the population in the future."

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Population

Population

Scant information is available on population status, densities, or population trends; it has been noted as locally common in the Mexican part of its range (P. Lavin pers. comm. 2005). Forstner et al. (2006) carried out range-wide surveys and found populations of the species concentrated in only a few stretches of the U.S. tributaries, whereas the species has minimal genetic structure across its range (Bailey et al. 2008).


Population Trend
Unknown
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Threats

Degree of Threat: Medium

Comments: The apparent distributional hiatus between the Rio Grande and Pecos River populations in Texas possibly results from pollution from runoff from oil and natural gas wells (Ward 1984).

Riverine and riparian habitat along the lower Rio Grande has been degraded by dams, flood control practices, stream channelization, water diversion, and tamarisk invasion; water quality has declined, and streamflow has become increasingly intermittent (Blackstun et al. 1998, Bailey et al. 2008).

In New Mexico, apparent declines have been attributed to degradation of habitat through stream dewatering, loss of vegetation, and pollution (Schmitt et al. 1985, cited but not referenced by Biota Information System of New Mexico).

Some turtles are killed wantonly by anglers or gunners. Bailey et al. (2008) observed several that had been shot or otherwise killed at fishing camps in Texas. Reportedly wild-caught individuals have been offered for sale in the pet trade in recent years (Bailey et al. 2008). Disappearance from a locality in Texas may have been associated with commercial exploitation and exportation (Dixon 2000).

The role that disease may play in the population dynamics of this species is unknown.

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Major Threats

An apparent absence of the species over a 160-km stretch of the lower Pecos was attributed to river pollution by natural gas and oilfield runoff (Ward 1984). Water diversion, runoff interception, groundwater pumping and other intensive water usage in the basin mean that the Rio Grande frequently runs dry before reaching the sea, while floodplain lake habitat has been lost after the construction of flood mitigation dams and infrastructure. These processes fragment populations and impede repopulation of depleted populations and gene flow.

The species is also considered to be under potentially serious threat from collection for the pet trade and wanton killing by fishermen (Forstner pers. comm. 2005, Bailey et al. 2008). Bailey et al. (2008) also reported an apparent absence of juveniles in the Texas populations of P. gorzugi, whereas their searches for juveniles in New Mexico were successful; they expressed their concerns for future population dynamics of Texas populations.

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Management

Conservation Actions

Conservation Actions

Turtles in general are protected from exploitation under Mexican wildlife and natural resource legislation. The species may occur, but has apparently not been confirmed, in the Bitter Lakes Wildlife Refuge of New Mexico. Surveys for the species in the Big Bend NP - Maderas del Carmen FFPA - Rio Grande National Scenic River – Amistad NRA, and the Lower Rio Grande Valley NWR, areas are desirable. Surveys of the Canon de Santa Elena FFPA have failed to record the species (MX Red List Workshop participants 2005).

Studies of its natural history and conservation status are warranted. Based on study results, the species may warrant specific legal protection in the USA. Commercial pet trade demand for the species can probably be met through captive breeding.

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Relevance to Humans and Ecosystems

Benefits

Economic Uses

Comments: This species has been exploited for use in the commercial pet trade (e.g., see Dixon 2000 and Bailey et al. 2008). Declared exports from the United States during 2003-2005 totaled 32 wild individuals (all in 2004) (World Chelonian Trust; http://www.chelonia.org/articles/us/USmarket_37.htm).

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Risks

Stewardship Overview: The primary management needs are protection and restoration of riverine and riparian habitats, and protection against commerical exploitation and wanton killing.

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Wikipedia

Rio Grande cooter

The Rio Grande cooter (Pseudemys gorzugi) is a species of turtle in the Emydidae family.

Distribution[edit]

The Rio Grande cooter is found in the Rio Grande drainage of Mexico (Chihuahua, Coahuila, Nuevo León, Tamaulipas), New Mexico, and Texas.[1][2]

Etymology[edit]

The specific name, gorzugi, is in honor of George R. Zug, Curator of Amphibians and Reptiles, National Museum of Natural History.[3]

References[edit]

  1. ^ a b c Rhodin 2011, p. 000.181
  2. ^ a b Fritz, Uwe; Peter Havaš (2007). "Checklist of Chelonians of the World". Vertebrate Zoology 57 (2): 195. Archived from the original on 2010-12-17. Retrieved 29 May 2012. 
  3. ^ Beltz, Ellin. 2006. Scientific and Common Names of the Reptiles and Amphibians of North America – Explained. ebeltz.net/herps/biogappx.html#B.
Bibliography
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Names and Taxonomy

Taxonomy

Comments: Pseudemys gorzugi originally was described as a subspecies of P. concinna (Ward 1984). It was treated as a full species by Ernst (1990), who noted the lack of evidence of gene exchange between gorzugi and the closest concinna populations (P. c. metteri), and by Seidel (1994). See Seidel (1994) for a morphometric analysis and taxonomic treatment of the genus Pseudemys.. See Stephens and Wiens (2003) for genetic data supporting the distinctiveness of P. gorzugi.

Existing DNA data indicate that this species is genetically relatively homogeneous across its range (Bailey et al. 2008).

This species has been treated in the literature also under the names Pseudemys concinna texana and Pseudemys floridana concinna; Pseudemys texana also has been treated under these names.

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