Acanthochelys pallidipectoris 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Testudines Chelidae

Scientific Name: Acanthochelys pallidipectoris (Freiberg, 1945)
Common Name(s):
English Chaco Side-necked Turtle
Spanish Tortuga chata
Platemys pallidipectoris Freiberg, 1945
Taxonomic Source(s): Fritz, U. and Havas, P. 2007. Checklist of chelonians of the world. Vertebrate Zoology 57(2): 149-368.

Assessment Information [top]

Red List Category & Criteria: Endangered A2cde+3cde+4cde; C1+2a(i) ver 3.1
Year Published: 2016
Date Assessed: 2014-07-12
Assessor(s): Vinke, T. & Vinke, S.
Reviewer(s): Rhodin, A.G.J., van Dijk, P.P. & Horne, B.D.
Contributor(s): IUCN Red Listing and Action Planning Workshop for Chelonians of the Southern Cone
Facilitator/Compiler(s): van Dijk, P.P. & Rhodin, A.G.J.

Acanthochelys pallidipectoris has been assessed as Endangered due to past, ongoing, and projected future population declines (A2, A3 and A4) as a result of habitat degradation and loss (c), ongoing illegal collection for the international pet trade (d), and competition with and predation by native species (e) expanding into A. pallidipectoris habitat as a result of habitat conversion. While generation time is not determined for the species, it is conservatively estimated at 15 years; considering trends over the past 30 years (two generations), and expected habitat loss and invasive impacts over the next 15 years, a 50% loss of suitable habitat and thus total adult populations is more than likely. Especially its dependence on a rare microhabitat of impenetrable soils and natural shallow depressions that allows rain water to collect in shallow ponds in combination with the high value of the same habitat to be altered for cattle-farming has increased the risk for A. pallidipectoris through microhabitat destruction. In addition, its low population numbers (and in many cases the historical age) of known occurrences, and small densities within the populations indicates an extremely small total population size, estimated at well below 2,500 mature animals, thus meeting criteria C1 and C2a(i).

Acanthochelys pallidipectoris
was last assessed in 1996, as VU A1c + D1. Since then, the situation of habitat destruction has changed dramatically. Paraguay (SEAM 2014) and Argentina (Prado 2012) list A. pallidipectoris as Endangered at the national level, which also was supported on the species level by the participants of the IUCN Red Listing and Action Planning Workshop for Chelonians of the Southern Cone, Filadelfia, Paraguay, 15-19 April 2012, including the Bolivian representative.  

Previously published Red List assessments:

Geographic Range [top]

Range Description:

Acanthochelys pallidipectoris is limited to the arid part of the Gran Chaco of Argentina, Paraguay and Bolivia (Vinke et al. 2011). There is only one record outside of the dry Chaco, in Mendoza, Argentina, but this is apparently of anthropogenic origin (Richard 1999).

Within its native range the species has been reported from 26 locations of which some are older than 20 years and for many of these it is unclear whether there actually are populations still persisting today, while other, even more recently cited, locations are known to have been transformed into cattle farms (T. Vinke and S. Vinke pers. obs.).

Countries occurrence:
Argentina; Bolivia, Plurinational States of; Paraguay
Additional data:
Number of Locations:26Continuing decline in number of locations:Yes
Range Map:Click here to open the map viewer and explore range.

Population [top]


Total population size of Acanthochelys pallidipectoris is unknown and no estimates have been published; in 1996 the species was assessed as Vulnerable under criterion D1 (<1,000 mature individuals) and until today there is no evidence that this was an underestimation.

This species does not achieve high densities. It lives in extremely small populations (Richard 1999, Vinke et al. 2011). Even after heavy rains, they are not numerous. No more than three specimens were discovered in an area of about 10 km2 even under optimal conditions like first heavy rain in spring (Vinke et al. 2011). The highest known number of individuals in a single population was observed in the National Park Chaco, Province of El Chaco, Argentina, with 21 specimens in an area of 13 ha, living in a dense net of shallow, ephemeral artificial and natural ponds (Paszko and Hernando 2005).

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:500-5000, 1000Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:Unknown
Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:

Acanthochelys pallidipectoris is a small freshwater turtle species that normally reaches carapace lengths of 12.8-16.2 cm (review by Vinke et al. 2011), with a maximum carapace length of 17.5 cm CL reported (female, holotype, Freiberg 1945). Females are a little larger and higher domed than males (Pazko and Hernando 2005). Fully-grown adults weigh about 400 g (Richard and Bertonatti, 1998). Hatchlings measure about 31 mm CL (Pazko and Hernando 2005, Métrailler 2008).

Reproduction is little-known in this species. Both males and females appear mature at about 13-14 cm CL and 325-400 g (Horne 1993). Mating occurs terrestrially during the short rainy season at the peak of the summer (Pazko and Hernando 2005, Gonzales et al.2006). Apparently a single clutch of 2-5 eggs is produced per year (Richard 1991, Horne 1993) in captive conditions, though it is likely that in the wild the species may only breed during optimal years. Age at maturity, longevity and generation length appear unknown for this species. Generation length is conservatively estimated at 15 years, by analogy with other small chelid turtle species inhabiting strongly seasonal arid habitats (e.g. Pseudemydura umbrina:  Kuchling and Bradshaw, 1993).

The limitations of the arid habitat portions of the Chaco means that A. pallidipectoris only occurs in temporarily flooded lowlands of the dry shrub forest with impenetrable soils (clay) and river-bed-like depressions that provide shallow water collected during the infrequent but heavy summer rains (Pazko and Hernando 2005, Vinke et al. 2011; T. Vinke and S. Vinke pers. obs.). In Mendoza, Argentina, a non-native population of this species occurs in a network of small artificial lagoons and ponds (Richard 1999).

The active period is restricted to the rainy season (less than six months, sometimes only four months), between October and March. The animals hibernate during the cooler dry season, terrestrially under Bromelia spp. and Aechma in the Natural Park Chaco (Pazko and Hernando 2005). The species feeds on a variety of small aquatic prey, mainly insects but also spiders, tadpoles, fish, and small organisms from the water surface (Richard 1999).

Systems:Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):15
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: Acanthochelys pallidipectoris is highly desirable in the international pet trade and while it is legally protected in all of its range countries, adult and sub-adult animals continue to be offered for sale in the international Internet trade. As it is not known what numbers of animals are collected and what the population dynamics of the species are, it is impossible to estimate the impact of trade; however, by analogy with other slow-growing turtles with low density and low distribution potential, the impact of collection of adult animals from the wild is likely severe.

Threats [top]

Major Threat(s):

The main threat to A. pallidipectoris is habitat degradation and loss. The Gran Chaco region and especially the more arid part, the Dry Chaco, is highly appreciated for cattle-farming (Paraguay, Bolivia) and soy bean culture (Argentina). In the last decade the deforestation rates of the arid Chaco have increased dramatically. The main areas of deforestation in Paraguay and Argentina match closely the distribution map of the species (compare Hansen et al. 2013).

In the main area of occurrence of A. pallidipectoris in Paraguay, the Department Boquerón, a portion of 1.9 million ha (21.7 % of the total surface) received permits to be cleared between 2003 and 2012, of which 78.6% (1.6 million ha and 17.0% of the total surface) had been permitted in the last six years (2007-2012) (Torres 2008, Barrios Kuck and Torres 2013). It is expected that in the Paraguayan Chaco all suitable land (land not located within the national protected area system, or reserved for indigenous communities, or held as private protected areas) will have been transformed for cattle production by 2025 (Yanosky 2013). This trend is not any better in Argentina with an increase of the deforestation rate in the Chaco by 439% from 2011 to 2012 (43,717 to 235,601 ha), keeping nearly the high level also in 2013 (Vinke et al. 2011, Rodas et al. 2012, Palacios et al. 2013, Cardozo et al. 2014).

In contrast to Acanthochelys macrocephala, which seems to be adapting to the altered landscape by opportunistically utilizing artificial cattle ponds (Vinke and Vinke 2001, 2008), this development is fatal for A. pallidipectoris due to its dependence of the above described microhabitat. For the cattle farmers the clay soil of those lowland depressions is of extreme high value and therefore this habitat type is widely destroyed by digging it out either directly as deep water reservoirs for cattle or by using the soil to build high tanks for the same function. Both of these destroy the habitat for A. pallidipectoris. The clay soil is also excavated for use in road building.

In Argentina the greatest threat is due to extensive habitat loss through intensive monocultures of soybean, especially in the provinces of Chaco, Formosa, Santiago del Estero, northwestern Santa Fe and northeastern Salta. This monoculture leads to a serious risk regarding the stability of the complete Chaco ecosystem, and therefore to the populations of A. pallidipectoris, which only is found within the few isolated remains of the native Chaco vegetation. A survey of the region of the Chaco of the province Salta in 2009 showed the huge devastation (E. Richard pers. obs.; Vinke et al. 2011), leaving the native fauna without suitable habitat.

In addition in Paraguay, competition with A. macrocephala and Caiman yacare, which have both migrated into the dry Chaco following the habitat modification of cattle farming and cattle ponds, are apparent threats in places where more water is available (Vinke and Vinke 2008). Finally, data suggest that changing climate regimes causing drought and abnormally low temperatures in winter and extremely high temperatures in spring and summer are likely to become a threat in the future (i.e. the 2007 winter was the coldest on record in South America, and the drought in 2008-2009 lasted for 16 months in the Chaco (T. Vinke and S. Vinke pers. obs.).

Although the species is legally protected in all of its range countries, more or less continuous offers of sale are observed in the international Internet trade. However, it is not known how many animals are collected illegally, nor from which countries or sites (Vinke et al. 2011), but the effects on wild populations are probably significant.

Conservation Actions [top]

Conservation Actions:

Acanthochelys pallidipectoris has protected status in Paraguay and Argentina.  It is not included in the CITES Appendices or other international conservation regulations. The species is not known to occur in any National Park or other protected area in Paraguay (Vinke and Vinke 2008), but has been reported from the Chaco NP in Argentina (Cabrera 1998, Pazko and Hernando 2005), and the only encounter of the species in Bolivia took place in a National Reserve (El Corbalán, Tarija).

Research into the conservation biology of the species is needed, specifically its status and trends in population numbers, as well as research into its basic natural history, seasonal cycles, population dynamics, habitat usage, and dispersal patterns (specifically its ability to re-colonize suitable habitat sites where populations have been extirpated).

Enforcement of current protected status is required; specimens continue to be available in the international pet trade (Vinke et al. 2011), indicating that existing protection is not effective. Inclusion in the CITES Appendices may be considered to address trade in importing countries.

Classifications [top]

4. Grassland -> 4.6. Grassland - Subtropical/Tropical Seasonally Wet/Flooded
5. Wetlands (inland) -> 5.3. Wetlands (inland) - Shrub Dominated Wetlands
5. Wetlands (inland) -> 5.8. Wetlands (inland) - Seasonal/Intermittent Freshwater Marshes/Pools (under 8ha)
15. Artificial/Aquatic & Marine -> 15.2. Artificial/Aquatic - Ponds (below 8ha)
1. Land/water protection -> 1.1. Site/area protection
2. Land/water management -> 2.1. Site/area management
2. Land/water management -> 2.2. Invasive/problematic species control
2. Land/water management -> 2.3. Habitat & natural process restoration
4. Education & awareness -> 4.3. Awareness & communications
5. Law & policy -> 5.1. Legislation -> 5.1.1. International level
5. Law & policy -> 5.4. Compliance and enforcement -> 5.4.2. National level

In-Place Research, Monitoring and Planning
  Action Recovery plan:No
  Systematic monitoring scheme:No
In-Place Land/Water Protection and Management
  Conservation sites identified:No
  Occur in at least one PA:Yes
  Area based regional management plan:No
  Invasive species control or prevention:Unknown
In-Place Species Management
  Harvest management plan:No
  Successfully reintroduced or introduced beningly:No
  Subject to ex-situ conservation:No
In-Place Education
  Subject to recent education and awareness programmes:Unknown
  Included in international legislation:No
  Subject to any international management/trade controls:No
11. Climate change & severe weather -> 11.2. Droughts
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Causing/Could cause fluctuations ⇒ Impact score:Medium Impact: 7 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

11. Climate change & severe weather -> 11.3. Temperature extremes
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Causing/Could cause fluctuations ⇒ Impact score:Medium Impact: 7 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.3. Agro-industry farming
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

2. Agriculture & aquaculture -> 2.3. Livestock farming & ranching -> 2.3.3. Agro-industry grazing, ranching or farming
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Causing/Could cause fluctuations ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

5. Biological resource use -> 5.4. Fishing & harvesting aquatic resources -> 5.4.1. Intentional use: (subsistence/small scale) [harvest]
♦ timing:Ongoing ♦ scope:Minority (<50%) ♦ severity:Rapid Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.2. Species disturbance

1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.3. Life history & ecology
1. Research -> 1.5. Threats
1. Research -> 1.6. Actions
2. Conservation Planning -> 2.1. Species Action/Recovery Plan
3. Monitoring -> 3.1. Population trends
3. Monitoring -> 3.2. Harvest level trends
3. Monitoring -> 3.3. Trade trends
3. Monitoring -> 3.4. Habitat trends

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Citation: Vinke, T. & Vinke, S. 2016. Acanthochelys pallidipectoris. In: . The IUCN Red List of Threatened Species 2016: e.T75A3139283. . Downloaded on 20 September 2018.
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