Mitracarpus maxwelliae

No Common Name

Description

Mitracarpus maxwelliae is a low, densely branching, moundlike shrub that may reach 8 in (20.3 cm) in height. Its somewhat woody branches are striate and sharply angled. The leaves are opposite, sessile, linear or linear-lanceolate, densely scabrous, 0.4-1 in (10.2-25.4 mm) long, and 0.1-0.2 in (2.5-5.1 mm) wide. The flower heads are terminal, dense, subglobose, and 0.3-0.5 in (7.6-12.7 mm) in diameter. The corolla is white, narrowly funnel-formed, minutely glandular-papillose, and approximately 0.2-0.25 in (approximately 5-6 mm) long. The capsule is about 0.06 in (1.5 mm) in diameter, opening by a transverse circular split near the middle. The seeds are ellipsoid, brownish-black, 0.05 in (1.3 mm) long, and 0.03 in (0.8 mm) wide.

Habitat

M. maxwelliae is found along an unpaved road, growing on dry exposed gravel in the municipality of Guánica, Puerto Rico.

Distribution

A small shrub endemic to southwestern Puerto Rico, M. maxwelliae was discovered on March 8, 1925, by Nathaniel L. Britton on a limestone hill in the municipality of Guánica. The site was later re-discovered by Alain Liogier in 1982 and again by George R. Proctor and Miguel Canals in 1987. The species has never been found at any other location. At this locality, it is found along an unpaved road, growing on dry exposed gravel. Approximately 1,443 plants, including mature flowering individuals and seedlings, were counted within an area of about 80,729 sq ft (7,500 sq m).

Threats

M. maxwelliae 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.

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. maxwelliae is found.

The most critical threat to the survival of this species is habit degrada tion and destruction. The shrub is threatened by road construction, recreational activities, wildfires, and land clearing associated with development for agriculture and other purposes.

The Commonwealth of Puerto Rico has adopted a regulation that recognizes and provides protection for certain commonwealth listed species. When M. maxwelliae gained federal listing in September 1994, the species 1) was provided a measure of immediate protection, 2) was added to the commonwealth list, and 3) became more likely to receive funding for recovery actions.

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. 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 it 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

Center for Plant Conservation. 1992. "Report on the Rare Plants of Puerto Rico." Missouri Botanical Garden, St. Louis.

"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 maxwelliae Britton & Wilson." In Publicacion Cientifica Miscelánea no. 2. Department of Natural Resources, San Juan, Puerto Rico.

U. S. Fish and Wildlife Service. 1994 "Endangered and Threatened Wildlife and Plants; Proposed Endangered Status for Three Puerto Rican Plants." Federal Register 59 (1): 44-47.