Calyptronoma rivalis

Calyptronoma rivalis is a pinnately compound leaved palm species which is found in Haiti, the Dominican Republic and Puerto Rico. Its common names include palma de manaca and Puerto Rican manac. C. rivalis stems grow singly and reach heights of 4–15 m, with stems 15–30 cm in diameter. It grows in waterlogged areas near the banks of streams; in Hispaniola is occurs below 450 m above sea level, and Calyptronoma plumeriana replaces it above that elevation.

This palm was added to the endangered species list of the United States in 1990, with a threatened status. At that time it was believed to be endemic to Puerto Rico and limited to three populations with an estimated 220 total individuals remaining. In 1995, botanists revised the taxonomy of genus Calyptronoma, placing Calyptronoma quisqueyana in synonymy with the rare palm. Then the species included all of the individuals previously named C. quisqueyana, extending its distribution to the island of Hispaniola. There it is not uncommon. Furthermore, its numbers on Puerto Rico increased to over 500, and then it was introduced to a few new areas on the island. The United States Fish and Wildlife Service will not remove the palm from the endangered species list yet because its Puerto Rican members are on private land, are not protected, and in some cases, are not reproducing successfully. The plants are located on land that is threatened with habitat destruction from development and habitat degradation resulting from poor management. The palm is more plentiful on Hispaniola, but its status there is not well known.