Polystichum calderonense

No Common Name

Description

Polystichum calderonenseis an evergreen terrestrial fern. It has a curved-ascending, 0.3 in (7 mm) thick rhizome that is clothed at the apex with lanceolate to oblong, curved, shining black, marginate scales up to 0.4 in (10 mm) long. Its fronds are erect to spreading and may reach 23.5 in (60 cm) in length. The twice-pinnate blades are lanceolate, 10-15.5 in (25-40 cm) long, 2.5-5.5 in (6-14 cm) wide, and narrowed and truncate at the apex. Blades terminate in a scaly proliferous bud that is somewhat narrowed toward the base. This species has 30-36 pairs of oblique, short-stalked pinnae. It has a characteristic 1.5-2.8 in (4-7 cm) long and 0.4-0.5 in (0.9-1.3 cm) wide middle pinnae, with eight to ten pairs of free pinnules. The tissue is dark green, rigid, and opaque. One to five sori are found dorsally on the veins of each pinnule, but are not clearly arranged in rows. The sori are covered by a light brown, deciduous, thin indusium.

Habitat

The plants grow on moist, shaded, noncalcareous ledges on mountain tops at elevations of 3,280-3,770 ft (1,000-1,150 m).

Distribution

P. calderonense was described in 1985 from specimens collected from the summit of La Silla de Calderon, Monte Guilarte Commonwealth Forest, in the municipality of Adjuntas, Puerto Rico. A second population was found in 1987 on Cerrote de Peñuelas, in the municipality of Peñuelas, Puerto Rico. Fifty-seven individual plants are known from the two localities: 45 (including juveniles) on La Silla de Calderon and 12 on Cerrote Peñuelas.

Threats

Both known populations ofP. calderonense are vulnerable to indiscriminate cutting or fires. In Peñuelas, the plants are on private lands that may be affected by industrial or residential development Although P. calderonense occurs within the Guilarte Commonwealth Forest, this population may be affected by forest management practices.

Habitat modification, including indirect effects that alter the microclimatic conditions, may dramatically affect this species. These populations are vulnerable to damage caused by hurricanes.

Collecting for private collections could present a problem, especially after the publicity generated following this species' listing.

Conservation and Recovery

Research is needed to determine this species' life history and ecological requirements and to develop and refine propagation and transplant techniques. Surveys are needed to determine if other populations exist and to locate potential transplant sites.

Contacts

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

U. S. Fish and Wildlife Service
Boquerón Ecological Services Field Office
P. O. Box 491
Boquerón, Puerto Rico 00622-0491
Telephone: (787) 851-7297
Fax: (787) 851-7440

Reference

U. S. Fish and Wildlife Service. 9 June 1993. "De-termination of Endangered or Threatened Status for Four Endemic Puerto Rican Ferns." Federal Register 58 (109): 32308-32311.