Two new species of rattans (Calamus, Arecaceae) from forests over limestone in the Philippines

We describe two novel diminutive species of Calamus, C. carsicola and C. warayanus, from the islands of Samar and Siargao, Philippines. Despite their respective similarities with the more variable and widely-distributed C. discolor and C. microsphaerion, both new taxa are distinctive by a suite of unique morphological character combinations. These new rattans are both characterized by their very slender clustering habit and are apparently restricted to forests over limestone. Relevant taxonomic notes and preliminary IUCN conservation status are herein provided.