Inventory of Rubiaceae species in Mt. Pao Range, Ilocos Norte, Northwestern Luzon, Philippines

Abstract. Batuyong MAR, Calaramo MA, Alejandro GJD. 2021. Inventory of Rubiaceae species in Mt. Pao Range, Ilocos Norte, Northwestern Luzon, Philippines. Biodiversitas 22: 3604-3612. Botanical assessments in the Philippines are mostly conducted on declared Protected Areas (PAs). However, many remaining potentially interesting and largely unexplored floristic sites are not considered PA, one of which is the Mt. Pao Range in the Municipality of Adams, located in Ilocos Norte, Philippines. Among the flowering plant family, Rubiaceae is one with the largest number of endemic species and genera in the Philippines Thus, floristic surveys of Rubiaceae species were conducted, and collections were made from September 2019 to March 2021. A total of 39 species belonging to 13 tribes and 24 genera of the family were recorded. These constitute 7.09% of the total Philippine Rubiaceae. Of these species, 18 are Philippine endemics while two are considered narrow endemic to Mt. Pao. Two endemic genera were also found in the area Antherostele and Kanapia. According to the Updated National List of Threatened Philippine Plants, their conservation status in the Department of Environment and Natural Resources (DENR) Administrative Order No. 2017-11 found one species assessed as Critically Endangered (Antherostele callophylla). This study contributes to the data on the distribution and occurrence of Philippine Rubiaceae. Moreover, it also highlights the area's importance with the presence of threatened and endemic species as an area of concern for protection and conservation.