Ctenosaura nolascensis 

Scope:Global
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_onStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Iguanidae

Scientific Name: Ctenosaura nolascensis
Species Authority: Smith, 1972
Common Name(s):
English Nolasco Spiny-tailed Iguana, San Pedro Nolasco Spiny-tailed Iguana
Spanish Iguana Blanca de Nolasco, Iguana Espinosa de Nolasco
Synonym(s):
Ctenosaura hemilopha subspecies nolascensis Smith, 1972
Taxonomic Source(s): Reynoso, V.H., Zarza-Franco, E. and Sánchez-Vilchis, M. 2010. Filogeografía del complejo Ctenosaura hemilopha con genes mitocondriales. Extended abstract. In: V.H. Reynoso and W. Medina-Mantecón (eds), XIII Reunión Nacional sobre Iguanas, Hermosillo Sonora, México, pp. 151-169.
Taxonomic Notes: There has been considerable debate over the species status of the Nolasco Spiny-tailed Iguana, and it is often referenced in the literature as Ctenosaura hemilopha hemilopha (Lowe and Norris 1955) or Ctenosaura hemilopha nolascensis (Smith 1972). The iguana was most recently recognized at the species level by Grismer (1999a). Genetic components of two lineages have been detected within the island (Cryder 1999, Davy et al. 2010, Reynoso et al. 2010).

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2012
Date Assessed: 2012-02-26
Assessor(s): Reynoso, V.H. & Pasachnik, S.
Reviewer(s): Grant, T. & Desbiez, A.
Contributor(s): Gonzalez-Monfil, G. & Zarza-Franco, E.
Justification:
The Nolasco Spiny-tailed Iguana is known only from the island of San Pedro Nolasco, Mexico. Iguanas are found throughout the approximately 3 km² island. Though this iguana has a very restricted range, the population size is not known to be decreasing or subject to extreme fluctuations. However, there are a number of threats and potential future threats, which, once these start to cause any declines, the species would immediately qualify for a Critically Endangered listing given the small size of the area and it essentially being a single location for most of the threats listed.

Geographic Range [top]

Range Description:Nolasco Spiny-tailed Iguana is found only on the island of San Pedro Nolasco, Sonora, Mexico (Smith 1972; Grismer 1999a,b). The island is approximately 3 km² and the iguana occurs from sea level up to 328 m.
Countries occurrence:
Native:
Mexico (Sonora)
Estimated area of occupancy (AOO) - km2:3
Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):No
Estimated extent of occurrence (EOO) - km2:3
Continuing decline in extent of occurrence (EOO):No
Extreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1
Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Lower elevation limit (metres):1
Upper elevation limit (metres):328
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

The population size is unknown but thought to be less than 2,500 animals due to its restriction on San Pedro Nolasco Island. However, the density on the island appears to be high. Approximately 40 individuals were observed during a single day of sampling on a 0.5 km transect, resulting in an estimate of 80 iguanas/km (V. Reynoso pers. comm. 2005).

No historic population size data are available. It is known that iguanas are being extracted for the pet trade, however, the threat is minimal and the population is thought to be currently stable.

Current Population Trend:Stable
Additional data:
Number of mature individuals:1000-2499Continuing decline of mature individuals:No
Extreme fluctuations:UnknownPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes

Habitat and Ecology [top]

Habitat and Ecology:The Nolasco Spiny-tailed Iguana is most often found under rocks, within hollow trees, and on cacti within tropical dry shrubland and rocky shoreline between 0-50 m above sea level. The island of San Pedro Nolasco is completely undisturbed by human activities other than fishing and sport diving. This iguana is primarily herbivorous, specializing on cacti fruits of the Organ Pipe Cactus (Stenocereus thurberi) and the endemic Near Threatened Isla San Pedro Cactus (Echinocereus websterianus) after the flowering season. In very dry seasons, iguanas may eat the stems of Cholla (Cylindropuntia spp.).
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:No

Use and Trade [top]

Use and Trade: Nolasco Spiny-tailed Iguanas occur within the pet trade on a limited scale. Historically this species may also have been hunted for food but this practice is believed to have ceased.

Threats [top]

Major Threat(s): The primary threats to the Nolasco Spiny-tailed Iguana are severe weather and climate change, causing habitat shifts, drought, extreme temperature, and hurricanes. High temperatures are particularly harmful to eggs and hatchlings. Invasive alien rats occur on the island, however, the degree to which they negatively affect the iguana population is unknown. Genetic data suggests that there may be some hybridization on the island with Ctenosaura conspicuosa (Davy et al. 2010). Additional research is needed to quantify this occurrence and determine if this poses a future threat to the species.

Nolasco Spiny-tailed Iguanas occur within the pet trade on a limited scale. Historically this species may also have been hunted for food but this practice is believed to have ceased.

Conservation Actions [top]

Conservation Actions: Mexican Law forbids national and international trade and lists this species with Special Protection under the name of Ctenosaura hemilopha (NOM-059-2010). However, there are no international regulations in place, such as the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), to protect the Nolasco Spiny-tailed Iguana from international trade. San Pedro Nolasco Island is part of the Gulf of California Biosphere Reserve. Settlements cannot be constructed and the extraction of flora and fauna is not permitted in this area. The island can only be visited with special permits and research is regulated. Though proper laws to protect these iguanas exist, additional enforcement is needed in order to regulate the extraction of individuals for the pet trade. A national plan to regulate invasive alien rats is in place, however, action on this plan has not yet been initiated on this island.

Additional research is needed to characterize the life history, taxonomy, and population trends of this iguana.

Classifications [top]

3. Shrubland -> 3.5. Shrubland - Subtropical/Tropical Dry
suitability: Suitable  major importance:Yes
12. Marine Intertidal -> 12.1. Marine Intertidal - Rocky Shoreline
suitability: Suitable  major importance:No
2. Land/water management -> 2.2. Invasive/problematic species control
5. Law & policy -> 5.1. Legislation -> 5.1.1. International level
5. Law & policy -> 5.4. Compliance and enforcement -> 5.4.1. International level
5. Law & policy -> 5.4. Compliance and enforcement -> 5.4.2. National level
5. Law & policy -> 5.4. Compliance and enforcement -> 5.4.3. Sub-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:Yes, over entire range
  Occur in at least one PA:Yes
  Percentage of population protected by PAs (0-100):91-100
  Area based regional management plan:Yes
  Invasive species control or prevention:Yes
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:No
  Included in international legislation:No
  Subject to any international management/trade controls:No
5. Biological resource use -> 5.1. Hunting & trapping terrestrial animals -> 5.1.1. Intentional use (species is the target)
♦ timing: Ongoing ♦ scope: Minority (<50%) ♦ severity: No decline ⇒ Impact score: Low Impact: 4 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

8. Invasive & other problematic species & genes -> 8.1. Invasive non-native/alien species -> 8.1.2. Named species
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.7. Reduced reproductive success

11. Climate change & severe weather -> 11.1. Habitat shifting & alteration
♦ timing: Future ♦ scope: Whole (>90%) ♦ severity: Slow, Significant Declines ⇒ Impact score: Low Impact: 5 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 2. Species Stresses -> 2.1. Species mortality

11. Climate change & severe weather -> 11.2. Droughts
♦ timing: Future ♦ scope: Majority (50-90%) ♦ severity: Rapid Declines ⇒ Impact score: Low Impact: 5 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 2. Species Stresses -> 2.1. Species mortality

11. Climate change & severe weather -> 11.3. Temperature extremes
♦ timing: Future ♦ scope: Majority (50-90%) ♦ severity: Very Rapid Declines ⇒ Impact score: Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 2. Species Stresses -> 2.1. Species mortality
  • 2. Species Stresses -> 2.3. Indirect species effects -> 2.3.7. Reduced reproductive success

11. Climate change & severe weather -> 11.4. Storms & flooding
♦ timing: Future ♦ scope: Minority (<50%) ♦ severity: Rapid Declines ⇒ Impact score: Low Impact: 4 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 2. Species Stresses -> 2.1. Species mortality

1. Research -> 1.1. Taxonomy
1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.3. Life history & ecology

♦  Pets/display animals, horticulture
 National : ✓  International : ✓ 

Bibliography [top]

Cryder, M.R. 1999. Molecular Systematics and Evolution of the Ctenosaura hemilopha Complex (Squamata: Iguanidae). Master's Thesis. Loma Linda University.

Davy, C.M., Méndez de la Cruz, F.R., Lathrop, A. and Murphy, R.W. 2010. Seri Indian traditional knowledge and molecular biology agree: no express train for island-hopping spiny-tailed iguanas in the Sea of Cortés. Journal of Biogeography 38(2): 272-284.

Grismer, L.L. 1999. An evolutionary classification of reptiles on islands in the Gulf of California, México. Herpetologica 55(4): 446-469.

Grismer, L.L. 1999. Checklist of the amphibians and reptiles on islands in the Gulf of California. Bulletin of the Southern California Academy of Sciences 98(2): 45-56.

IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.1). Available at: http://www.iucnredlist.org. (Accessed: 19 June 2012).

Lowe Jr., C.H. and Norris, K.S. 1955. Analysis of the herpetofauna of Baja California, Mexico, III: new and revived reptilian subspecies of Isla de San Esteban, Gulf of California, Sonora, Mexico, with notes on other satellite islands in the Gulf of California. Herpetologica 11(2): 89-96.

Reynoso, V.H., Zarza-Franco, E. and Sánchez-Vilchis, M. 2010. Filogeografía del complejo Ctenosaura hemilopha con genes mitocondriales. Extended abstract. In: V.H. Reynoso and W. Medina-Mantecón (eds), XIII Reunión Nacional sobre Iguanas, Hermosillo Sonora, México, pp. 151-169.

Smith, H.M. 1972. The Sonoran subspecies of the lizard Ctenosaura hemilopha. The Great Basin Naturalist 32(2): 104-111.


Citation: Reynoso, V.H. & Pasachnik, S. 2012. Ctenosaura nolascensis. In: The IUCN Red List of Threatened Species 2012: e.T174477A1414514. . Downloaded on 06 February 2016.
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