Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Caryophyllales Cactaceae

Scientific Name: Opuntia megarrhiza
Species Authority: Rose
Common Name(s):
Spanish Nopalillo
Taxonomic Notes: Originally described by J.N. Rose in 1906. Later recognized by Britton and Rose (1919) and by Bravo (1978). Recently studied by Hernández et al. (2001).

Hunt et al. (2006) treat O. pachyrriza as being conspecific with O. megarrhiza, but that treatment is not followed here and O. pachyrriza is assessed separately.

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii,v)+2ab(iii,v) ver 3.1
Year Published: 2013
Date Assessed: 2009-11-18
Assessor(s): Hernández, H.M., Gómez-Hinostrosa, C., Goettsch, B.K. & Sotomayor, M.
Reviewer(s): Chanson, J.S.
Facilitator/Compiler(s): Hilton-Taylor, C.
This species qualifies as Endangered because it has a small extent of occurrence (less than 1,895 km²), its population comprises three disjunct subpopulations comprising three locations, and the quality of its habitat is expected to decline in the long term due to the intensification of human activities, and there is significant harvest occuring from the wild.
Previously published Red List assessments:
2002 Endangered (EN)

Geographic Range [top]

Range Description: This species is restricted to some fragments of the summits of La Trinidad and Álvarez mountain ranges, in San Luis Potosí, Mexico. The extent of occurrence is ca 1,895 km², and it is fragmented into three subpopulations with an area of occupancy of ca 20-50 km².
Countries occurrence:
Mexico (San Luis Potosí)
Estimated area of occupancy (AOO) - km2: 25-50
Number of Locations: 3
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The population size is less than 2,500 mature individuals. The species is known from eight localities aggregated into three subpopulations.
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 2499 Continuing decline of mature individuals: Yes

Habitat and Ecology [top]

Habitat and Ecology: It is found in areas of disturbed grassland of Bouteloua gracilis or Heteropogon contortus, and chaparral of Quercus striatula or Q. edwardii on the tops of mountains. The soils are relatively deep-dark clay, with limestone outcrops.
The cladodes of this species die back in the winter months and regrow in the spring as an adaptation to withstand freezing and the impacts of fire.
Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes

Use and Trade [top]

Use and Trade: The rhizomes of this species are collected for medicinal use as an anti-inflammatory for broken bones.

Threats [top]

Major Threat(s): The natural vegetation is almost totally modified, due to livestock raising. The species is under some pressure due to its medicinal uses.

Conservation Actions [top]

Conservation Actions: The species is listed on CITES Appendix II. Two thirds of the known localities of this species are within a decreed protected area (Area Natural Protegida del Real de Guadalcázar). The effective conservation of this area would ensure the survival of the species. The medicinal value of the species has to be verified through scientific research. Its possible utilization could lead to its conservation through management.

Citation: Hernández, H.M., Gómez-Hinostrosa, C., Goettsch, B.K. & Sotomayor, M. 2013. Opuntia megarrhiza. The IUCN Red List of Threatened Species 2013: e.T41219A2952324. . Downloaded on 09 October 2015.
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