Cycas micronesica


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Cycas micronesica
Species Authority: K.D.Hill

Assessment Information [top]

Red List Category & Criteria: Endangered A3ce ver 3.1
Year Published: 2010
Date Assessed: 2009-10-31
Assessor(s): Marler, T., Haynes, J. & Lindstrom, A.
Reviewer(s): Donaldson, J.S. & Bösenberg, J.D.
According to the available data, populations on Yap and Palau are relatively stable. Populations on Rota are declining due to development and are highly vulnerable to scale invasion, and populations on Guam are declining rapidly. The subpopulations on Guam make up most of the known subpopulations and 50% of the plants. The measured decline of 3% in five years is expected to increase as heavily infested plants die. Seedlings and juveniles have also died back completely on Guam meaning there is no replacement of adults. It is therefore anticipated that the decline over the current and future generations (capped at 100 years from now) will exceed 50%.
2006 Endangered (IUCN 2006)
2006 Endangered
2003 Near Threatened (IUCN 2003)
2003 Near Threatened

Geographic Range [top]

Range Description:This species occurs in Micronesia, the Marianas Group and the western Caroline Islands (but there is some uncertainty about its precise indigenous range). This species does not extend west into the Philippines. Plants occur on Palau Island and on Guam and Rota Islands of the Marianas group and on Yap Island of the Caroline Islands group.
For further information about this species, see 61316_Cycas_micronesica.pdf.
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Guam; Micronesia, Federated States of ; Northern Mariana Islands; Palau
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: This species was relatively abundant in the 1990s and recorded as locally common. However, populations on Guam have been devastated by the invasive Aulacaspis scale (CAS). A reference population in northwest Guam has declined from 686 individuals in early 2004 (before CAS reached this habitat) to 87 individuals in January 2007.
For further information about this species, see 61316_Cycas_micronesica.pdf.
A PDF viewer such as Adobe Reader is required.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: C. micronesica is an arborescent species that occurs in closed forest on coral limestone or coral sand, or occasionally on volcanic soils on islands where these occur.
Systems: Terrestrial

Threats [top]

Major Threat(s): All plants were removed from the islands of Saipan and Tinian (Northern Mariana islands) by the Japanese during World War II. There has also been habitat loss on both Guam and Rota (Northern Mariana Islands).

The Cycad Aulacaspis scale (an invasive from SE Asia) has caused substantial mortality. Current mortality is not necessarily a direct result of CAS. The Cycad Blue Butterfly arrived in 2005, and it spread throughout Guam within months. Moreover, several pre-existing arthropod pests that were causing minor damage to the C. micronesica plants have ramped up their damage now that the cycad population is in such poor health. Many of the deaths that are occurring today are a result of epidemic longhorn beetle (Dihammus marianarum) stem damage. Moreover, there is an alien invasive snail (Satsuma mercatorius) that has begun feeding on young leaflets and is now a new threat. This newly learned feeding behaviour by a herbivore may be the result of the compromised ability of the unhealthy cycad plants to adequately synthesize the chemicals that deter herbivory.

Conservation Actions [top]

Conservation Actions: This species is listed on Appendix II of the CITES Appendices.

Bibliography [top]

Donaldson, J.S. (ed.). 2003. Cycads. Status Survey and Conservation Action Plan. IUCN/SSC Cycad Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.

Hill, K.D. and Stevenson, D.W. 1998-2006. The Cycad Pages. Available at:

IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.3). Available at: (Accessed: 2 September 2010).

Jones, D.L. 2002. Cycads of the World (2nd edition). Smithsonian Institute Press, Washington, DC.

Marler, T. 2007. Guam Update - Email.

Terry, I. and Marler, T. 2005. Paradise Lost? Tipping the scales against Guam's Cycas micronesica. The Cycad Newsletter 28(3-4): 21-23.

Whitelock, L.M. 2002. The Cycads. Timber Press, Portland, Oregon.

Citation: Marler, T., Haynes, J. & Lindstrom, A. 2010. Cycas micronesica. In: The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 27 March 2015.
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