Mitracarpus polycladus

No Common Name

Description

Mitracarpus polycladus is a suffrutescent perennial. It is branched near the base, and the erect or spreading stems may reach up to 17.7 in (45 cm) in height. The branches are four-angled and glabrous (smooth; hairless). Leaves are opposite, linear to linear-lanceolate, 0.8-1.8 in (2-4.5 cm) long, 0.1-0.2 in (0.3-0.5 cm) wide, glabrous, and often have an inrolled margin and decurrent base. The inflorescence is terminal and capitate, 0.3-0.5 in (8-13 mm) in diameter, many flowered, and sub-tended by three bractlike leaves. The corolla is white, about 0.2 in (5 mm) long, with ovate leaves. The seed capsule is 0.06 in (1.5 mm) in diameter, splitting open transversely below the middle, and contains black seeds.

M. polycladus was first discovered growing on coastal rocks near Caña Gorda, Guánica, Puerto Rico, in 1886 by Paul Sintenis. It was also located on the island of Saba in the Lesser Antilles by the Dutch botanist I. Boldingh.

Habitat

M. polycladus grows in crevices and soil pockets of coastal rocks in arid areas near Caña Gorda, Guánica, Puerto Rico, and on the island of Saba in the Lesser Antilles.

The Guánica Commonwealth Forest lies within the subtropical dry forest life zone. Extensive areas of this life zone—including the area in which M. polycladus is found—overlie limestone. Mean annual precipitation is approximately 31 in (79 cm). Several vegetation associations have been identified in the Guánica Forest. This species falls within the associations identified as thorn scrub and rock plate, where the canopy is open and the trees are dwarfed by lack of soil and sea spray. The dominant species include Pictetia aculeata, Reynosia uncinata, and Comocladia dodonea.

Distribution

This species is known only from the island of Saba in the Lesser Antilles and from one locality in southwestern Puerto Rico. In Puerto Rico, it is limited to one coastal area in the Guánica Commonwealth Forest. Exact numbers of individuals have been difficult to estimate due to drought conditions.

Threats

M. polycladus is found along infrequently used roadways where it may be adversely impacted in the future. Any road improvement, widening, or increase in traffic along these roads would result in the loss of a significant portion of the only known populations. The site of this species is near preferred recreational areas, heavily utilized during the summer months. Fires are a frequent occurrence in these coastal dry forests.

One of the most important factors affecting the continued survival of this species is its limited distribution. Because so few individuals are known to occur in a limited area, the risk of extinction is extremely high. Wildfires are a frequent occurrence in this extremely dry portion of southwestern Puerto Rico, particularly in the coastal roadside areas of Guánica where M. polycladus is found.

Conservation and Recovery

Conservation measures provided to species listed as endangered or threatened under the Endangered Species Act (ESA) include recognition, recovery actions, requirements for federal protection, and prohibitions against certain practices that might be harmful to the species. Recognition through listing encourages and results in conservation actions by federal, commonwealth, and private agencies, groups, and individuals. The ESA provides for possible land acquisition and cooperation with the commonwealth and requires that recovery actions be carried out for all listed species.

Contacts

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
Telephone: (404) 679-4000
http://southeast.fws.gov/

Boquerón Ecological Services Field Office
Boquerón, Puerto Rico 00622-0491
Telephone: (787) 851-7297
Fax: (787) 851-7440

References

"Natural Heritage Program Status Information on Mitracarpus maxwelliae, Mitracarpus polycladus, and Eugenia woodburyana. " 1993. Department of Natural Resources, San Juan, Puerto Rico.

Proctor, G. R. 1991. "Status Report on Mitracarpus polycladus Urban." In Publicacion Cientifica Miscelánea no. 2. Department of Natural Resources, San Juan, Puerto Rico.

U. S. Fish and Wildlife Service. "Endangered and Threatened Wildlife and Plants; Proposed Endangered Status for Three Puerto Rican Plants." Federal Register 59 (1):44-47.