Pteris lidgatei

No Common Name

Description

Cheilanthes lidgatei was described in 1883 on the basis of a specimen collected on Oahu. The genus Schizostege was erected in 1888 for this anomalous species. In 1897, it was placed in the genus Pteris by H. Christ, resulting in the currently accepted combination Pteris lidgatei. P. lidgatei, a member of the maidenhair fern family (Adiantaceae), is a coarse herb 1.6-3.3 ft (0.5-1 m) in height. It has a horizontal rhizome that is 0.6 in (1.5 cm) thick and at least 3.9 in (10 cm) long at maturity. The fronds, including the leafstalks, are 24-37 in (61-94 cm) long and 8-18 in (20-45 cm) wide. The leafy portion of the frond is oblong-deltoid to broadly ovate-deltoid, thick, brittle, and dark gray-green. The sori are apparently marginal in position, either fused into long linear sori or more typically separated into distinct shorter sori with intermediate conditions being common. P. lidgatei can be distinguished from other species of Pteris in the Hawaiian Islands by the texture of its fronds and the tendency of the sori along the leaf margins to be broken into short segments instead of being fused into continuous marginal sori.

Habitat

P. lidgatei is found in lowland wet forest at elevations ranging from 1,750-3,000 ft (533-914 m). It is generally found on streambanks and next to waterfalls with mosses and other species of ferns. 'Ohi'a is the dominant native overstory tree species.

Distribution

P. lidgatei had historical occurrences at Olokui on Molokai and Waihee on West Maui. The species also occurred at four locations in the Koolau Mountains of Oahu: Waiahole, Lulumahu Stream, Kaluanui, and Wailupe. Seven populations of about 33 individuals were known in 1995. P. lidgatei is reported from Oahu at Kawaiiki Stream, North Waimano Gulch, Kawainui Drainage, and South Kaukonahua Gulch. Respective populations of 12 and eight plants were discovered on West Maui in 1994 at Kauaula Valley and Kahakuloa Stream. The extant populations of P. lidgatei are on Federal, state, and private land. Three of the Oahu populations are located on lands under the jurisdiction of the U.S. Army.

Threats

The primary threats to P. lidgatei are the alien plant Koster's curse, habitat destruction by feral pigs, and stochastic extinction.

Conservation and Recovery

Feral pig control efforts by The Nature Conservancy of Hawaii at Kapunakea Preserve have helped keep pigs from spreading into the Kauaula Valley population of P. lidgatei on Maui. The Army has prepared Endangered Species Management Plans for Oahu Training Areas; these plans highlight specific threats to endangered plants and recommend actions to promote recovery. The U.S. Fish and Wildlife Service is studying the environmental effects of establishing a National Wildlife Refuge in the Koolau Mountains. The priority recovery actions for this fern are control of feral ungulates and alien weeds. Although this species is presently very rare, the number of known plants is expected to rise slowly as botanists become more familiar with the plant and its preferred habitat. Additional populations should be carefully documented as they are discovered so that important habitat can be protected. The Koolau Mountains and West Maui Mountains should be targeted for protection.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Building
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

Reference

U.S. Fish and Wildlife Service. 1998. "Recovery Plan for Four Species of Hawaiian Ferns." U.S. Fish and Wildlife Service, Portland, Oregon.