Tanacetum oshanahanii 

Scope: Global & Europe
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Asterales Asteraceae

Scientific Name: Tanacetum oshanahanii Marrero Rodr., Febles & C.Suárez
Common Name(s):
Spanish Magarza de Guayedra

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B2ab(iii,v); C2a(i); D ver 3.1
Year Published: 2011
Date Assessed: 2011-03-04
Assessor(s): Febles Hernández, R., Naranjo Suárez, J. & Fernández-Palacios Acosta, O.
Reviewer(s): Bilz, M. & Peraza Zurita, M.D.
Tanacetum oshanahanii is listed as Critically Endangered because there is a single subpopulation known with 28 individuals with an area of occupancy of 1 km². Main threats are grazing and natural competition that cause a continuing decline in the extent and quality of its habitat and in the number of mature individuals. The conservation status of the species is alarming.

Geographic Range [top]

Range Description:This species is endemic to the island of Gran Canaria, Canary Islands, Spain (Febles et al. 2004). It appears restricted to the steep crags of Barranco de Guayedra, where it occupies a narrow strip (30 x 40 m), located between 550-600 m. The area of occupancy has been estimated in 1 km². Regressive trends are inferred for its distribution range (Gobierno de Canarias 2004).
Countries occurrence:
Spain (Canary Is.)
Additional data:
Estimated area of occupancy (AOO) - km2:1
Number of Locations:1
Lower elevation limit (metres):550
Upper elevation limit (metres):600
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There is only one known population with 28 individuals. Only individuals located on the cliff and a cave (17 total) are in good condition while individuals located in the upper platform (11 individuals) are affected by goats and drought. Regressive trends have not been observed, but growth patterns have not been observed neither, in the last 13 years, and decreasing population trends are inferred for its current population size (Gobierno de Canarias 2004).
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:28
Population severely fragmented:No
All individuals in one subpopulation:Yes

Habitat and Ecology [top]

Habitat and Ecology:It grows in cracks and crevices of crags walls, within rupicolous communities. Accompanying species include Aeonium virgineum, Aenium manriqueorum, Asparagus umbellatus, Olea europaea ssp. guanchica, Heberdenia excelsa, Convolvulus canariensis, Hypericum grandifolium, Pteridium aquilinum and Sonchus platylepis. It can also be found in ledges of cliffs where its main companions are: Cistus monspeliensis, Euphorbia regis-jubae and Kleinia neriifolia.

This hermaphrodite species presents high percentages of non-viable seeds, which indicates possible reproduction problems. Inbreeding could also be an issue.

Threats [top]

Major Threat(s): The narrow strip where the species can be located is under threat from plant competition and livestock grazing which prevents optimal development in the upper and lower platforms (Febles et al. 2004). Main natural competitors are Pteridium aquilinum and Cistus monspeliensis. The presence of individuals with high percentages of non-viable seeds is also a threat.

Conservation Actions [top]

Conservation Actions: This species is listed under Appendix I of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention). It is listed as species "En peligro de extinción" in the national and regional catalogues of threatened species. It is classed as Critically Endangered B2ab(iii,v); C2a(i); D in the Spanish Red List (Moreno 2008).

It occurs within the protected area Parque Natural de Tamadaba. There are seeds stored in the germplasm bank of the Jardín Canario Viera y Clavijo, where the species is cultivated.

Population trends have to be monitored and research about the reproductive biology of the species should be developed. Natural competitors should be eradicated in its distribution area.

Citation: Febles Hernández, R., Naranjo Suárez, J. & Fernández-Palacios Acosta, O. 2011. Tanacetum oshanahanii. The IUCN Red List of Threatened Species 2011: e.T165126A5977975. . Downloaded on 16 July 2018.
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