Philippine Journal of Science 150 (S1): 487-502, Special Issue on Biodiversity ISSN 0031 - 7683 Date Received: 05 Oct 2020 Diversity of Rubiaceae in Ilocos Norte, Northwestern Luzon, Philippines: A Preliminary Checklist, Their Distribution, and Conservation Status Mae Ann R. Batuyong1,2, Michael A. Calaramo3, and Grecebio Jonathan D. Alejandro1,4 1The Graduate School, University of Santo Tomas España Blvd. 1015 Manila, Philippines 2Department of Biological Sciences, College of Arts and Sciences Mariano Marcos State University, City of Batac 2906 Ilocos Norte, Philippines 3Garden Director and Curator, Northwestern University Ecological Park & Botanical Garden Airport Ave., Bengcag, Laoag City 2900 Ilocos Norte, Philippines ,4College of Science and Research Center for the Natural & Applied Sciences University of Santo Tomas, España Blvd. 1015 Manila, Philippines The northern Cordillera Mountain Range of Ilocos Norte is an important site for floristic studies in the northwestern part of the Philippines. However, most of its forested areas remain understudied and limited data are available on the structure of its floristic communities. Here, a preliminary checklist of Rubiaceae species in Ilocos Norte is provided with notes on their distribution and conservation status. The field survey was conducted from April 2019 to March 2020 in Kalbario Patapat Natural Park (KPNP), Metropolitan Ilocos Norte Watershed Forest Reserve (MINWFR), and Mt. Lammin. A total of 57 species belonging to 28 genera and 15 tribes were recorded, which constitute 10.36% of the total number of Philippine Rubiaceae species. The genera with the highest number of recorded species are Psychotria, Ixora, and Ophiorrhiza with nine, six, and four species, respectively. Of these species, 27 are Philippine endemics that are widely distributed, and four species are endemic to the province. Among the sites surveyed, the tropical evergreen lowland rain forest of KPNP had the highest number of recorded species. With regard to their conservation status according to the IUCN (International Union for Conservation of Nature) red list category, one was assessed as Endangered. Moreover, based on the updated national list of threatened Philippine plants and their categories identified in the DENR (Department of Environment and Natural Resources) AO (Administrative Order) No. 2017-11, two are listed as Threatened species, one Critically Endangered, and one Vulnerable. According to the IUCN red list categories and criteria (2019), the four endemic species in the province recognized in the study are categorized as follows: one Critically Endangered (Antherostele callophylla), one Endangered (Psychotria tayabensis var. castanea), and two Vulnerable (Antirhea microphylla and Pyrostria triflora). Keywords: biodiversity, conservation, floristic survey, Ilocos Norte, tropical rain forest *Corresponding Author: [email protected] 487 Philippine Journal of Science Batuyong et al.: Rubiaceae Species in Ilocos Vol. 150 No. S1, Special Issue on Biodiversity Norte, Northwestern Luzon, Philippines INTRODUCTION Based on the comprehensive global assessment of the family (Davis et al. 2009), the Philippines ranked among The Philippines is a top priority for biodiversity the 20 most diverse regions for Rubiaceae based on the conservation due to its rich flora and fauna and high total number of species and ranked third among the 20 endemism. This diversity is due to its tropical location, areas with the highest number of endemic species, wherein climatic conditions, and unique geological origins (Myers five genera are considered to be endemic to the country: et al. 2000; Brown et al. 2013). However, it is also one Antherostele Bremek., Greeniopsis Merr., Sulitia Merr., of the top countries considered as a biodiversity hotspot Villaria Rolfe, and the recently added genus Kanapia (Myers 1988, 1990, 2003; Myers et al. 2000; Mittermeier Arriola & Alejandro (Alejandro and Liede-Schumann et al. 2004, 2011; DENR-BMB 2015). The biota of many 2003; Alejandro 2007; Alejandro et al. 2010, 2011; of the regions in the country – which has a relative total Arriola et al. 2016). It is also one of the plant families land area of approximately 300,000 sq. km comprised of in the Philippines with the most number of threatened thousands of islands – is considered to be understudied, species (Fernando et al. 2008). Thus, the need for further and many of its flora and fauna are waiting to be described. taxonomic research on Rubiaceae is substantial. Although One important site for floristic studies in the northwestern the study of Ordas et al. (2019) provided a checklist of portion of the country is the northern Cordillera Mountain species of Rubiaceae in Eastern Samar Visayas, wherein Ranges in Ilocos Norte (Vallejo 2014). It is a part of the 37 out of the 59 species recorded are endemic. More northwestern mountains of Luzon Island – which covers studies of the plant family are necessary, such as studies the Kalinga-Apayao area in its northern part; the Ilocos- that will provide an update on the existing information, Cagayan boundary as its southern outpost; and Abra, especially on the occurrence and distribution of endemic including Ilocos Sur, as its western boundary. The area species. These are necessary for underpinning specific is composed of different types of terrestrial ecosystems species management plans for conservation and protection – from montane mossy forests and forests over limestone priorities (Harris 2012). to seasonally dry lowland tropical rain forests (Calaramo et al. 2016). It also contains the last frontier of contiguous old-growth forests in the Ilocos Region that extends to Cagayan and Cordillera (DENR 2018). Aside from these, MATERIALS AND METHODS several newly described plant species were documented from Ilocos Norte – such as Amorphophallus adamsensis Study Site (Magtoto et al. 2013), Begonia palemlemensis (Calaramo Fieldwork was conducted in four localities within the et al. 2019b), Dendrobium elineae (Naive et al. 2019), northern Cordillera Mountain Ranges of Ilocos Norte Nepenthes aenigma (Gronemeyer et al. 2016), Pyrostria covering the following – namely KPNP, MINWFR, and triflora (Arriola et al. 2015), Robiquetia ilocosnortensis Mt. Lammin. (Calaramo et al. 2019a), and Thrixpermum nicolasiorum (Calaramo et al. 2018). The KPNP (Figures 1, 2A, and 2B) is one of the remaining Natural Parks in the Philippines that retains Most of the forested areas in Ilocos Norte are still relatively its key biodiversity area status (DENR-BMB 2016). scarce on plant inventories. The works of Magtoto and It was established under Proclamation No. 1275 s. Austria (2017) on the pteridophytes of Adams and 2007, under Republic Act No. 7586 or the National Batuyong et al. (2020) on the checklist of vascular plants Integrated Protected Areas (NIPAS) Act of 1992. This in the limestone forest of MINWFR are the only recent 38-sq.-km natural park with a 19.37-sq.-km buffer floristic studies documented. According to Ong et al. zone is located on the mountains of the Municipalities (2002), the major challenge in conserving the country's of Pagudpud and Adams. KPNP is the only remaining biological diversity is that baseline information is limited, remnants of an old-growth mix dipterocarp forest on the incomplete, or lacking and widespread. Also, existing data northwestern portion of Luzon contiguous to Cagayan of previously recorded species need updating in terms of and Cordillera (DENR 2018). Its highest peak is part biology, distribution, occurrence, and abundance. Hence, of Mt. Palemlem range at 1,294 m above sea level to ensure this, there should be a maintained and continuing (masl). The KPNP is generally described as a tropical biological inventory. evergreen lowland rainforest and is bound by the Type 3 climate of Cagayan receiving a large amount of rainfall The Rubiaceae or coffee family represents one of throughout the monsoon season (Modified Corona the largest families of angiosperms of trees, shrubs, Climate Classification). geofructices, herbs, and lianas (Robbrecht 1988) – with approximately 550 species in about 80 genera recognized The MINWFR (Figures 1 and 2D), on the other hand, in the country (Govaerts et al. 2006; Alejandro 2007). is considered one of the remaining important limestone 488 Philippine Journal of Science Batuyong et al.: Rubiaceae Species in Ilocos Vol. 150 No. S1, Special Issue on Biodiversity Norte, Northwestern Luzon, Philippines Figure 1. Location of the study areas in Ilocos Norte, Northwestern Luzon, Philippines. Areas surveyed are marked in colors. areas found on the island of Luzon (Batuyong et al. It lies between geographical coordinates of 120°37'00"– 2020). Initially, it is established as a component by the 120°41'00" N and 18°21'00"–18°24'00" E and is described NIPAS through Presidential Proclamation No. 731 but is as a lowland forest. Like MINWFR, Mt Lammin also currently proposed to be a regular protected area (PA). has a Type I climate with two main seasons – dry from MINWFR is situated in the Municipality of Pasuquin with November–April when most trees lose their leaves and an estimated land area of 20.75 sq. km and a buffer zone wet the rest of the year. of 4.12 sq. km, lying between geographical coordinates of 120°37'00"–120°41'00" N and 18°21'00"–18°24'00" Processing of Permits E. The highest altitude in the municipality is 564 m Permits from respective local government units (LGU) directly adjacent to the PA. This PA is classified as Type were secured before the actual field survey and collection 1 climate (Modified Corona Climate Classification) with of specimens in these areas. A gratuitous permit (GP) was pronounced wet months from April–November, turning obtained from the DENR Region 1 Office with the GP the area into lush greenery where numerous seasonal No. 2019-007. herbs and shrubs grow and the trees sprawl into a thick canopy. Plants that can withstand the dry season remain only during the dry months, but the sparse and small Survey, Collection, Processing, and Identification of stunted trees over rocky ridges dominate such as the Specimens species Podocarpus polystachyus R.