Philippine Journal of Science 150 (3): 907-921, June 2021 ISSN 0031 - 7683 Date Received: 19 Nov 2020

Rubiaceae Flora of Northern Sierra Madre Natural Park, , , : Richness, Distribution, and Conservation Status

Rachel D. Biag1,2* and Grecebio Jonathan D. Alejandro1,3

1The Graduate School, University of Santo Tomas España Blvd., 1015 Philippines 2Department of Natural Sciences, College of Arts and Sciences State University Carig Campus City, Cagayan 3500 Philippines 3College of Science and Research Centre for the Natural & Applied Sciences University of Santo Tomas, España Blvd., Manila 1015 Philippines

The Northern Sierra Madre Natural Park (NSMNP) in Isabela, Philippines holds the record of being the widest remaining tropical rainforest on the island of Luzon. However, this park remains underexplored in terms of its flora. A few botanical studies have been conducted but were particularly focused on the general floristic diversity of the area. No botanical studies have been done yet concentrated on a particular . Species conservation and protection could be more resounding if attention is given to a particular group of like the very diverse family. Hence, an initial checklist of Rubiaceae species in NSMNP is provided with accounts in their richness, distribution, and conservation status. The botanical exploration was conducted in April–August 2019 in NSMNP, specifically in the coastal areas – namely, , , and – and a non-coastal zone, . In total, 52 Rubiaceae species were recorded belonging to 23 genera and representing 15 tribes of the family. The number of species constitutes about 9.72% of the total number of species in the country. The most specious among the tribes belong to (9), followed by Spermacoceae (8), Naucleeae and Urophylleae (6), and (5). Of these species, 31 are Philippine endemic, while two are considered narrow endemic to the province. As regards their conservation status based on the International Union of Conservation of Nature (IUCN) list of threatened species, one was assessed as critically endangered (CR) and another one as endangered (EN). Further, two more species were recognized as highly threatened (HT), being CR species, and two other species were assessed as vulnerable (VU) based on the Updated National List of Threatened Philippine Plants and Their Categories found in the Department of Environment and Natural Resources (DENR) Administrative Order No. 2017-11.

Keywords: angiosperms, biodiversity, botanical survey, conservation, NSMNP

*Corresponding Author: [email protected] [email protected]

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INTRODUCTION Philippines. Based on the very comprehensive global assessment of Rubiaceae by Davis et al. (2009), the The Philippines is one of the world’s major centers of Philippines ranked 10th (number of species = 535) out biodiversity and endemism (Sinha and Heaney 2006; of Rubiaceae's 20 most diverse regions. Moreover, as to Balatibat 2008; BMB 2016; Ani and Castillo 2020). the gross number of endemic Rubiaceae species, it was However, it has received much less attention from the worthy of note that the Philippines was part of the top international conservation community than many other five highest areas (1st – , 2nd – , countries, which are less biodiverse and with fewer 3rd – the Philippines, 4th – , 5th – ). Of endemic species (Oliver and Heaney 1996). The country’s the 535 species, 443 (83%) are endemic to the country rich diversity, speciation, and endemicity are due to its (Davis et al. 2009), and an evaluation of the Philippine tropical location, climate patterns, and island effect. On Rubiaceae manifested a total of 80 genera (Alejandro and top of the enormous biological importance of the country Liede 2003), of which six are cultivated which comprises supporting a wide variety of fauna and flora, the high 12.1% of the Rubiaceae genera worldwide. It is also endemicity amongst species, the rate of deforestation, worthy of mentioning that Rubiaceae is just one among and other degrading factors is another reason why the the eudicotyledons flowering plants with the biggest Philippines has still been regarded up to now as one of the number of indigenous species in the Philippines with hottest hotspots and one of the higher priority countries in five endemic genera – namely, Antherostele Bremek., the world for conservation. This is the almost total lack of Greeniopsis Merr., Kanapia Arriola & Alejandro, awareness about the prior factors among the vast majority Sulitia Merr, and Villaria Rolfe (Alejandro and Liede of Filipino people, even within the government and other 2003; Alejandro et al. 2010, 2011; Arriola et al. 2016). decision-making sectors (Sinha and Heaney 2006). Also, Rubiaceae is among the main families of plants The NSMNP found in the Province of Isabela in Northern contributing to the threatened plant list (Fernando et al. Luzon, Philippines, is one of the 17 critical conservation 2008). Ordas et al. (2019) documented in their study priority areas identified by the UNESCO (United Nations several Rubiaceae species assessed as threatened – Educational, Scientific, and Cultural Organization) Greeniopsis discolor Merr., Greeniopsis euphlebia Merr., and the DENR, and one of the country’s ten priority Greeniopsis megalantha Merr., Greeniopsis multiflora protected areas (PAs) (van der Ploeg et al. 2011; DENR (Elmer) Merr., silagoensis Banag, Manalastas & 2017b). It holds the record of being the widest remaining Alejandro, and conglomeratiflora Sohmer tropical rainforest in the Island of Luzon and yet one & Davis, to mention a few. puberula Arriola of the least biologically explored areas in the country & Alejandro, philippinensis Arriola & (DENR 2017b). In other words, it is just among those Alejandro, and papafranciscoi Alejandro were PAs needing attention. Countable botanical studies have all evaluated as critically endangered species (Arriola been carried out in this national park and are particularly and Alejandro 2013, 2015; Alejandro 2015). Also, focused on the area's general floristic composition. It has Salamanes et al. (2015) assessed surigaoensis to be noted that the great botanist and conservationist Salamanes and Alejandro as CR. Leonardo Co made his pioneering works in this park – Since endemicity is evident in this plant family (Alejandro specifically in Palanan, Isabela, where various species and Liede 2003; Banag et al. 2017) and restricted belonging to different plant families were collected and distribution increases the likelihood of extinction of documented (Co et al. 2006). This species list had been species, it is imperative to do floristic studies on those updated by Guingab (2019), but most of the data were affected groups like Rubiaceae. Currently, NSMNP’s still based on the field surveys conducted in the 1990s. rich biodiversity is under severe threat from the local In this study, a total of 241 woody species in 58 families population's extreme poverty, which directly impacts and 118 genera were recorded. The Rubiaceae family its degradation and exploitation of the virgin forest will was found to be one of the most species-rich families be logged over within several years (Guingab 2019). next to Myrtaceae with 21 and 25 species, respectively. This simply means that species could disappear anytime It was until then that no more information about its floral without them being identified yet. We could not afford this diversity had been obtained. thing to happen. More so, that we won’t allow hectares Being the fourth largest family of angiosperms based of threatened species’ habitat to be cleared without any on the number of species and the fifth-largest by the assessments done. Hence, this study is conducted. number of genera (Davis et al. 2009), the Rubiaceae or coffee family is extremely diverse. It calls for a huge number of research studies. Continuous fieldwork and taxonomic studies must be done to explore this plant family's unexplored diversity, especially in the

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MATERIALS AND METHOD Palanan One of the four coastal areas in the Province of Isabela and situated on 122°9’ to 122°32’ E and 16°50” to 17°10’ Study Areas N in the mid-easternmost part of the province within the Fieldwork was done in one of the most important PAs NSMNP, and it is bound on the east by the Philippine in Luzon, Philippines – the NSMNP. It is located in the Sea. This remote town is generally mountainous and eastern mid part of Isabela Province at geographical grids thickly forested, with a large portion of its land classified between 15° 59’35” to 18° 3’11” N and 121° 17’35” to as rolling to moderately steep (18–30% slope) covering 122° 33’29” E (Figure 1a). The park has a total area of about 57.35% of the area. Its climate falls under Type IV 359,486 ha corresponding geographically with the four of Coronas’ classification, characterized by more or less eastern coastal municipalities of Palanan, Divilacan, even rain distribution throughout the year. The mountain Maconacon, and , and portions of San Mariano, soils are typically categorized as undifferentiated (DENR San Pablo, Cabagan, , and at the western 2017b). slopes of Sierra Madre.

It is bounded on the west by the and on Divilacan the east by the Pacific Ocean. Its elevation ranges from Another coastal area in the northeastern part of Isabela 200–1,844 m above sea level with a slope that is steep to with coordinates 17°20’N 122°18’E. It is also mountainous very steep (DENR 2017b). The municipalities covered like Palanan, and thick natural forests still cover many of by the NSMNP that are surveyed are described below. its flatlands. It is also characterized by the rolling to

Figure 1a. Map of the Philippines showing the location of the NSMNP. Areas surveyed are marked in yellow stars (DENR 2017b).

909 Philippine Journal of Science Biag and Alejandro: Rubiaceae Flora of NSMNP, Vol. 150 No. 3, June 2021 Luzon, Philippines moderately steep slope category (18–30%). The Type quality images in Co's Digital Flora of the Philippines IV classification of the climatic condition is observed, (Pelser et al. 2011 onwards), as well as digital herbarium and undifferentiated mountain soils dominate in the area specimens available through Plants of the World Online (DENR 2017b). (POWO) (http://www.plantsoftheworldonline.org/) and Global Biodiversity Information Facility (https://www. gbif.org/), was also made. With these, the identity of the Maconacon species was known. Consultation to the World Checklist One of the most remote and isolated coastal municipalities of Rubiaceae (Govaerts 2011), International Plant Names in northeastern Isabela is situated at 17°23’14” N, Index (2020), and POWO (2020) was done to provide the 122°14’17” E. It is thickly forested and, in terms of its correct scientific name for each species. slope, it is classified as very steep (50% and above). The same climate and soil types, as previously mentioned, characterized this town (DENR 2017b). Determination of Endemicity and Conservation Status To determine whether the species is endemic to the Cabagan Philippines, restricted to a province, or not at all endemic, The town in the western portion of Isabela has the consultation to the Co’s Digital Flora of the Philippines coordinates 17°26’N, 121°46’E. It also falls under a very (Pelser et al. 2011 onwards) and various studies focused steep slope category (50% above). It has the Type III on Rubiaceae by the Thomasian Angiosperm Phylogeny climate characterized by not very distinct but relatively and Barcoding Group of University of Santo Tomas was dry for six months. This season is greatly affected by the done. The conservation status of each species was assessed southwest monsoon. Data from World Weather Online using the IUCN Red List of Threatened Species (https:// show that the dry months are from February–April with www.iucnredlist.org/) and the Updated National List of a range of 5–11 days of rainfall and a monthly average Threatened Plants in the Philippines (DENR 2017a). depth of 23, 27, and 28 mm, respectively (DENR 2017b).

Sampling, Collection, Processing, and Identification of Specimens RESULTS AND DISCUSSION Before the field activity, a gratuitous permit No. 2019-01 was secured at DENR Regional Office 2, Government List of Species and Taxonomic Notes on Endemic Center, Carig Sur, Tuguegarao City, since the site surveyed Species is a PA. This botanical study was conducted in four A total of 52 species belonging to 23 genera and field expeditions from April–August 2019. Purposive representing 15 tribes of family Rubiaceae were sampling was employed in the study. The collection documented in the NSMNP. Of the 52 Rubiaceae species was done along and approximately 10 m adjacent to recorded, 30 are shrubs, nine small to medium-sized trails at the study sites. All plants having the Rubiaceae trees, nine herbs, and four vines (Table 1). The most characters were collected during their reproductive specious tribes belong to Psychotrieae (9), followed by stages to ensure precise identification of species. These Spermacoceae (8), Naucleeae and Urophylleae (6), and collections underwent the standard process of drying, Coffeeae (5). The rest of the tribes were represented by pressing, and mounting. Voucher specimens were then less than five species: Ixoreae (4); Mussaendeae (4); deposited in the Environmental Information Center Morindeae and Octotropideae (2); and Aleisanthieae, Herbarium, Isabela State University, Cabagan (EICH- , Ophiorrhizeae, Palicoureeae, Pavetteae, ISUC). A list of specimens examined was provided in the and Vanguerieae (1). It should be recalled that a Appendix. Comprehensive morphological examinations botanical exploration was conducted before by Co et al. of each specimen's vegetative and reproductive parts (2006) – specifically in the lowland ultrabasic forest in were carried out using a foldable magnifier and cordless Palanan, Isabela. In this survey, 21 species of Rubiaceae Prepscope compound microscope. A vernier caliper belonging to the tribes Guettardeae, Vanguerieae, was utilized whenever the measurement of a part is Coffeeae, Aleisanthieae, Ixoreae, Pavetteae, Morindeae, required. Character states presented for each species and Psychotrieae were documented. In the current study, were based on Beentje (2016). For easier identification, 52 species under the same family were recorded, hence herbarium specimens from local herbaria such as the updating the natural park's species composition. Philippine National Herbarium (PNH), the University of the Philippines Herbarium (PUH), the University The municipality of Palanan, covered by NSMNP, harbors of Santo Tomas Herbarium (USTH), and EICH-ISUC 28 different species – hence being the most species-rich – were observed. A comparison of our materials with good followed by Divilacan, Maconacon, and Cabagan having

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Table 1. Checklist of Rubiaceae species in NSMNP, Isabela, Northern Luzon, Philippines. Habit (T – tree, S – shrub, H – herb, V – vine), proposed status based on IUCN Red List of Threatened Species or the DENR Administrative Order 2017-11* (NE – Not Evaluated, DD – Data Deficient, OT – Other Threatened Species, LC – Least Concern, VU – Vulnerable, EN – Endangered, CR – Critically Endangered), endemicity (E – endemic, N – non-endemic), distribution (P – Palanan, D – Divilacan, M – Maconacon, C – Cabagan), coordinates, and accession numbers. Distribution Coordinates Accession Species Habit Status Endemicity number P D M C Latitude (N) Longitude (E) Tribe Aleisanthieae Greeniopsis discolor Merr. T CR* E + 17⁰19’11” 122⁰20’11” RDB 009 Tribe Coffeeae arabica L. S Cultivated N + + + 17⁰3’43” 122⁰25’24” RDB 003 17⁰19’34” 122⁰20’27” 17⁰24’6” 121⁰49’48” Coffea sp. S + + 17⁰1’15” 122⁰22’21” RDB 004 17⁰5’34 121⁰45’45” fasciculiflora (Elmer) S NE E + 17⁰1’15” 122⁰22’21” RDB 005 Elmer Discospermum sphaerocarpum S NE N + 17⁰19’56” 122⁰20’19” RDB 006 Dalzell ex Hook. F. Discospermum whitfordii (Elmer) S NE E + 17⁰21’26” 122⁰14’3” RDB 007 S.J. Ali and Robbr. Tribe Guettardeae Antirhea benguetensis (Elmer) S NE E + 17⁰19’9” 122⁰20’6” RDB 001 Valeton Tribe Ixoreae Ixora confertiflora Merr. S NE E + 17⁰1’16” 122⁰22’21” RDB 015 Ixora leucocarpa Elmer S NE E + 17⁰2’18” 122⁰23’18” RDB 016 Ixora longifolia Sm. S NE N + 17⁰19’34” 122⁰20’22” RDB 017 Ixora salicifolia (Blume) DC. S NE N + 17⁰19’28” 122⁰20’17” RDB 018 Tribe Morindeae citrifolia L. T NE N + + + 17⁰1’3” 122⁰24’8” RDB 020 17⁰19’55” 122⁰20’20” 17⁰21’29” 122⁰14’2” Prismatomeris brachypus Ridl. T NE E + + 17⁰19’31” 122⁰20’18” RDB 036 17⁰21’29” 122⁰14’6” Tribe Mussaendeae lanata C.B. Rob. S VU* E + 17⁰20’18” 121⁰40’45” RDB 021 Mussaenda philippica A. Rich. S LC E + + + + 17⁰1’3⁰ 122⁰24’14” RDB 022 var. philippica 17⁰19’55 122⁰20’20” 17⁰22’10” 122⁰14’9” 17⁰2’20” 122⁰23’16” Mussaenda philippica A. Rich. S EN E + + 17⁰2’20” 122⁰23’16” RDB 023 var. pubescens Alejandro 17⁰24’6” 122⁰14’9” Mussaenda sp. S + 17⁰19’39” 122⁰20’28 RDB 024 Tribe Naucleeae Neonauclea media (Havil.) Merr. T NE E + 17⁰21’49” 122⁰14’9” RDB 025 Neonauclea reticulata (Havil.) T NE N + + + 17⁰21’40” 122⁰14’10” RDB 026 Merr. 17⁰19’11” 122⁰20’11” 17⁰20’6” 121⁰45’45” cordata (Lour.) Merr. V NE N + 17⁰21’10” 121⁰49’45” RDB 048 Uncaria lanosa Wall. V NE N + 17⁰2’15” 122⁰23’37” RDB 049

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Distribution Coordinates Accession Species Habit Status Endemicity number P D M C Latitude (N) Longitude (E) Uncaria longiflora (Poir.) Merr. V NE N + 17⁰2’20” 122⁰23’15” RDB 050 Uncaria perrotettii Merr. V NE E + 17⁰2’22” 122⁰24’14” RDB 051 Tribe Octotropideae Hypobathrum glomeratum (Bartl. S NE E + 17⁰1’0” 122⁰24’8” RDB 014 ex. DC.) K. Schum. Villaria fasciculiflora Quisumb. S CR* E + 17⁰2’15” 122⁰23’38” RDB 052 & Merr. Tribe Ophiorrhizeae Ophiorrhiza oblongifolia DC. H NE E + 17⁰28’18” 121⁰40’45” RDB 028 Tribe Palicoureeae membranifolia (Bartl. S NE N + 17⁰19’34” 122⁰20’22 RDB 002 ex. DC.) Elmer Tribe Pavetteae barnesii Elmer ex. Merr. S NE N + 17⁰1’8” 122⁰24’5” RDB 029 Tribe Psychotrieae Psychotria gitingensis Elmer T DD E + 17⁰19’47” 122⁰20’28” RDB 037 Psychotria nitens Merr. S DD E + 17⁰19’50” 122⁰20’23” RDB 038 Psychotria pilosella ssp. T DD E + 17⁰19’39” 122⁰20’27” RDB 039 erythrotricha var. erythrotricha 17⁰21’29” 122⁰14’1” (Elmer) Sohmer & A.P. Davis Psychotria pubilimba Quisumb. S CR E + 17⁰2’21” 122⁰23’14” RDB 040 Psychotria reynosoi Sohmer & T DD E + + 17⁰21’26” 122⁰14’3” RDB 041 A.P. Davis Psychotria rubiginosa Elmer ex. T DD E + 17⁰19’43” 122⁰20’29” RDB 042 Merr. Psychotria subsessiliflora var. S DD E + 17⁰19’55” 122⁰20’20” RDB 043 carinata (Quisumb. & Merr.) Sohmer & A.P. Davis Psychotria tayabensis Elmer var. S DD E + 17⁰21’20” 121⁰46’45” RDB 044 euphlebia (Merr.) Sohmer & A.P. Davis Psychotria sp. S + 17⁰1’16” 122⁰22’21” RDB 045 Tribe Spermacoceae Exallage auricularia (L.) Bremek. H NE N + + 17⁰2’20” 122⁰23’16” RDB 008 Hedyotis bambusetorum Merr. H VU* E + + 17⁰1’28” 122⁰24’7” RDB 010 17⁰20’10” 122⁰14’9” Hedyotis simplex H NE E + 17⁰1’16” 122⁰22’2” RDB 011 Hedyotis sp. 1 H NE + + 17⁰19’28” 122⁰46’45” RDB 012 Hedyotis sp. 2 H NE + 17⁰3’43” 122⁰28’24” RDB 013 Spermacoce ocymoides Burm. F. H NE N + + 17⁰3’43” 122⁰25’24” RDB 046 17⁰17’56” 122⁰18’19” Spermacoce remota Lam. H NE N + + + 17⁰0’47” 122⁰24’15” RDB 047 17⁰19’11” 122⁰20'11” 17⁰20’11” 122⁰23’17” Oldenlandia corymbosa L. H NE N + 17⁰2’20” 122⁰23’17” RDB 027 Tribe Urophylleae Praravinia everettii Merr. S NE E + 17⁰20’1” 122⁰17’47” RDB 030 Praravinia glabra (Merr.) Bremek. S NE E + 17⁰1’16” 122⁰22’23” RDB 031

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Distribution Coordinates Accession Species Habit Status Endemicity number P D M C Latitude (N) Longitude (E) Praravinia loheri (Merr.) Bremek. S NE E + 17⁰2’19” 122⁰23’18” RDB 032 Praravinia sablanensis (Elmer) S NE E + 17⁰21’29” 122⁰14’6” RDB 033 Bremek. Praravinia viridescens (Elmer) S NE E + 17⁰2’21” 122⁰23’15” RDB 034 Bremek. Praravinia sp. S CR* + 17⁰1’13” 122⁰24’1” RDB 035 Tribe Vanguerieae Kanapia cf. monstrosa (A. Rich.) S NE E + 17⁰1’16” 122⁰22’21” RDB 019 Arriola & Alejandro Total 28 20 13 9

Figure 1b. Species richness of the surveyed sites.

20, 13, and nine species, respectively (Table 1; Figure Philippines amidst its degradation. 1b). This disparity in species richness in the surveyed sites is attributed to the climatic conditions these areas Among the tribes in which these species belong, Psychotrieae are exposed to. It has to be noted that Palanan, Divilacan, had the most number of species, as manifested in Table 1. and Maconacon are coastal areas in which the climate The said tribe was represented by the Psychotria L. falls under Type IV, which is characterized by more or It is distinguishable from other Rubiaceae genera through less even distribution of rain throughout the year based on its caducous stipule, terminal inflorescences, small corolla, the Coronas' classification. Cabagan, a non-coastal zone, stamens (i.e. filaments) inserted within the ring of corolla has the least number of species; this can also be explained throat hairs, pyrenes usually with ribs or ridges on the by its climatic condition, which is not very distinct but outer surface and two marginal preformed slits (also in relatively dry for six months – a characteristic of the Type the seed coat with a red pigment that is soluble in 70% III climate category. Most of the species were collected ethanol), and ruminate endosperm (Sohmer and Davis 2007; in the lowland dipterocarp forest, proving that this Razafimandimbison 2014). ecosystem is the most specious formation and structurally Currently, 112 species of Psychotria are recognized in the the most complex (DENR 2017b). This natural park still country where almost all are identified as endemic. In this has the largest area of a lowland dipterocarp forest in the study, nine Psychotria species (Figure 2) were encountered in the lowland dipterocarp forest from the study sites, and

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long; its fruits are turbinate, ribbed and distinctly wrinkled, and 8–10 mm long. A narrow endemic species (NES), known only in the provinces of Isabela and Cagayan, was also collected. This is the Psychotria pubilimba Quisumb., a shrub with a height of 1 m. The stipules are imbricate to lanceolate and about 0.8 cm long. The leaves are lanceolate-shaped measuring 11.5–22.3 × 2.5–6.4 cm, and the fruits appear as obovoid and ridged with each measuring 4–5 mm long. Following the IUCN criteria, its restricted distribution and occurrence as a singular mature individual in the municipality of Maconacon – which is also currently experiencing significant levels of environmental degradation – would qualify P. pubilimba under the category CR. This next species of Psychotria, which inhabits the municipality of Palanan, is P. reynosoi Sohmer & A.P. Davis. It is a small tree measuring about 4 m tall and has lanceolate stipules that are 2.4 cm long. The leaves are elliptically shaped measuring 8.5–19.4 × 2.5–8.1 cm, whereas its globose fruits are 11 mm long and coarsely ribbed. The Psychotria rubiginosa Elmer ex Merr. exists as a small tree measuring 5 m tall. Its stipules are valvate to ovate and measure 0.9 cm long. The leaf blades appear oblong to oblanceolate and each measures about 11.5–18.2 × 3.55–3.9 Figure 2. A) Psychotria gitingensis, B) Psychotria nitens, cm. The fruits are globose, 7 mm long, and ridged. C) Psychotria pubilimba, D) Psychotria pilosella ssp. erythrotricha var. erythrotricha, E) Psychotria Thriving in Divilacan, Psychotria subsessiliflora var. rubiginosa, F) Psychotria subsessiliflora var. carinata, G) carinata (Quisumb. & Merr.) Sohmer & A.P. Davis is a Psychotria sp., H) Psychotria reynosoi, and I) Psychotria 4-m-tall shrub having stipules that are valvate to triangular tayabensis var. euphlebia. Photos taken by R. Biag. and are 0.5 cm long. Also, leaf blades are elliptic to obovate, 13.3–16.6 × 4.7–6.8 cm in dimension, and coriaceous and grayish-brown when dry. The subsessile all are endemic to the country. Psychotria gitingensis Elmer fruits are obovoid in shape, 8 mm long, ribbed, and – widely distributed in Luzon, , and – distinctly wrinkled when dry. is a small tree about 5 m tall with stipules 0.8 cm long plus valvate and ovate-triangular shape, and lanceolate The only Psychotria species collected in a non-coastal leaf blades measuring 8–14 × 2.4–4.0 cm. The fruits are zone is the P. tayabensis Elmer var. euphlebia (Merr.) subobovoid to turbinate and ribbed, each measuring 6–8 Sohmer & A.P. Davis, which is a shrub about 1 m tall. Its mm long. Only the municipality of Divilacan harbors this stipules are triangular and 0.5 cm long. The leaf blades species, and 20 individuals were observed. appear elliptic and measure 12.7–14.3 × 3.9–5.3 cm. The fruits are sessile to globose and are about 5 mm long. A 1-m-tall shrub with lanceolate stipules and measuring 1 cm long was also encountered in the two surveyed sites An interesting species of Psychotria has been discovered (Divilacan and Maconacon). This species is Psychotria in the current study. Further investigations are required to nitens Merr. Its leaf blades are ovate to oblanceolate determine if it is a species new to science. This Psychotria measuring 11.6–19.4 × 3.2–6.1 cm, and its fruits are species assumes various leaf shapes (i.e. from oblong smooth and are about 6.3 cm long. to elliptic, lanceolate, and oblanceolate), measurement of 22.6–27 × 5.3–9.2 cm, and inflorescences (i.e. Another species encountered particularly in the trichotomous and 6 cm long). municipality of Divilacan is Psychotria pilosella subsp. erythrotricha var. erythrotricha (Elmer) Sohmer & A.P. The tribe Spermacoceae also displayed species richness. Four Davis, a small tree about 5–7 m tall. Stipules are valvate genera – namely, Hedyotis L., Spermacoce L., Oldenlandia to ovate and are 4 mm long. The leaf blades are elliptic, L., and Exallage Bremek – were given representations in obovate to narrowly oblanceolate, and 5–18 × 1.6–3 cm this study. Hedyotis L. is one of the largest genera within the

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Rubiaceae with 500–600 species (Alejandro 2015; Santor Philippine endemic species – is characterized by having 2016). The Philippines houses 36 species of Hedyotis, of spathulate stipule, obovate leaves measuring 17.5–21.5 × which 31 are endemic, and five are indigenous species (Pelser 8–12.5 cm with acuminate apex and cuneate base. Uncaria et al. 2011; Santor 2016). H. bambusetorum Merr. and H. perrottetii Merr. (Figure 3), one of the two endemic simplex Merr. (Figure 3) are endemic to the country and were species of this genus in the country, was also collected. recorded in the current study. The former has leaf blades According to Olivar et al. (2018), this is an interesting and petioles measuring 7.0–9.2 × 2.5–3.0 cm and > 10 mm, species since it is the only species endemic to the country respectively. On the other hand, the latter is characterized by showing a deeply laciniate stipule and a distinct violet having leaves that measure 7.0–9.0 × 2.8–3.4 cm and petioles color shoot system. that are > 20 mm long. Two other species of Hedyotis need further investigations to determine their identity up to the The tribe Coffeeae also stands out in terms of species species level. Of these two, one (Hedyotis sp. 1) seems to be richness. Five species were identified – namely, Coffea an interesting species since the observed traits did not fit any arabica L., Coffea sp., Diplospora fasciculiflora (Elmer) of the given characters using the taxonomic key for Hedyotis Elmer, Discospermum whitfordii (Elmer) S.J. Ali & Robbr. by Santor (2016); hence, it could potentially be a new species. (Figure 4), and Discospermum sphaerocarpum Dalzell ex The remaining genera were represented by the following Hook. f. Having decussate leaves that are usually elliptic, species – Spermacoce ocymoides Burm. F., Spermacoce shortly sheathing stipules, and short to long interpetiolar remota Lam., Oldenlandia corymbosa L., and Exallage awn are some of the synapomorphic characters of auricularia (L.) Bremek. – all of which are non-endemic. Diplospora DC. and Discospermum Dalz. (Ali and Robbrecht 1991). Larger leaves with acuminate leaf apex separate D. whitfordii from D. sphaerocarpum with smaller leaves and caudate leaf apex. Both have globose fruits measuring 13–16 × 13–15 mm. A singular individual of the endemic D. fasciculiflora and D. whitfordii and the non-endemic D. sphaerocarpum has been observed, which implies the need to heighten conservation efforts to prevent loss of these species. It is also noteworthy to mention that six species of

Figure 3. A) Neonauclea media, B) Hedyotis simplex, C) Hedyotis bambusetorum, D) Uncaria perrottetii, and E) Hedyotis sp. Photos taken by R. Biag.

Another species-rich tribe in this study is Naucleeae. It is represented by Neonauclea Merr. and Uncaria Schreb. Both can be easily recognized through their spherical inflorescences (Ordas et al. 2019) but distinguished by their habits. Neonauclea appears as shrubs and trees in Figure 4. A) Discospermum whitfordii, B) Praravinia everettii, a forest and river edges while Uncaria exists as woody C) Praravinia sablanensis, D) Praravinia viridescens, in low- to medium-elevation zones, as observed in E) Praravinia loheri, and F) Praravinia glabra. Photos the survey. The presence of paired fang hooks is a unique taken by R. Biag. character in the latter genus (Ridsdale 1978; Olivar et al. 2018). Neonauclea media (Havil.) Merr. (Figure 3) – a

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Praravinia Korth. (Figure 4) under the tribe Urophylleae, resulted in one specimen (Mussaenda philippica A. Rich. five of which are endemic to the country, were collected. var. philippica) having twigs and inflorescences that are Palanan serves as a host to P. loheri (Merr.) Bremek. (5), glabrous and the other two (Mussaenda lanata C.B. Rob., P. glabra (Merr.) Bremek. (2) and P. viridescences (Elmer) Mussaenda philippica A. Rich. var. pubescens Alejandro) Bremek. (2). P. sablanensis (Elmer) Bremek. (2) and P. with twigs and inflorescences that are conspicuously everettii Merr. (1), on the other hand, inhabit Maconacon. indumented. M. lanata and M. philippica var. pubescens Those in parentheses are the number of individuals show < 1 and > 1 mm indumentum, respectively. One collected per species. specimen was not identified up to the species level due to the lack of reproductive parts. The pantropical Ixora L., considered one of the largest Rubiaceae genera in the Philippines, was also represented One of the species collected in Palanan and Divilacan in this study. Of the 34 species present in the country, 25 under the tribe Morindeae greatly contributes to the are endemic species (Banag et al. 2015, 2017) with two Philippines' biodiversity: the Prismatomeris brachypus endemic (I. cf. confertiflora Merr. and I. leucocarpa Elmer) Ridl. (Figure 6). It exists as low- to medium-sized trees and two non-endemic species [I. longifolia Sm. and I. having elliptic to oblong leaves measuring about 7–16 salicifolia (Blume) DC] encountered during the survey. The × 2.3–5.8 cm, appearing subcoriaceous and shiny, with two endemic Ixora species found in Palanan are disparate ventral and dorsal sides dark brown and pale brown, through their stipules, being subtruncate and connate for I. respectively. Stipules are triangular measuring 3 mm long. leucocarpa and triangular and unfused for I. confertiflora. The fruits are globose, white to black in color, and 10 mm Furthermore, they are distinguished through their leaves – I. long. Morinda citrifolia L. – a non-endemic species – leucocarpa being larger (23.5–27 × 9.7–10.6 cm) compared was found widely distributed in Palanan, Divilacan, and with I. confertiflora, which are smaller (9–15 × 2–5.5 cm). Maconacon. Its leaves, when dry, are chartaceous and measure 20–22 × 9–9.5 cm. Representative species from the tribe Mussaendeae (Figure 5) were likewise encountered from the surveyed The tribe Octotropideae is an equally important group sites. Morphological examinations of these species in the natural park because of Villaria fasciculiflora Quisumb. & Merr. (Figure 6), which is classified as an NES because its occurrence is restricted only to Isabela

A B

C D Figure 6. A) Prismatomeris brachypus, B) Villaria fasciculiflora, Figure 5. A) Ixora leucocarpa, B) Mussaenda philippica var. C) Antirhea benguetensis, D) Greeniopsis discolor, pubescens, C) Mussaenda philippica var. philippica, D) E) Kanapia cf. monstrosum, and F) Ophiorrhiza Mussaenda lanata. Photo taken by R. Biag. oblongifolia. Photos taken by R. Biag.

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and provinces. It is characterized by a combination were recorded in the study sites. These include of characters – including elliptic leaf blades measuring Greeniopsis, Kanapia, and Villaria. 13.5–19 × 4.0–6.3 cm, and fruits that measure about 5 × 3 mm when dry, are distinctly wrinkled, and have persistent Two species, namely Psychotria pubilimba and Mussaenda calyces. Hypobathrum glomeratum (Bartl. ex. DC.) K. philippica var. pubescens are the threatened flora found Schum. also adds up to this tribe. in the park with their conservation status of CR and EN, respectively, based on the IUCN criteria. Following the The rest of the species – namely, Greeniopsis discolor recommendations issued by DENR DAO 2017-11, two Merr. (Aleisanthieae), Antirhea benguetensis (Elmer) CR (Greeniopsis discolor and Villaria fasciculiflora) Valeton (Guettardeae), Ophiorrhiza oblongifolia DC. and two VU (Hedyotis bambusetorum and Mussaenda (Ophiorrhizeae), Chassalia membranifolia (Palicoureeae), lanata) species were also documented in the study. The Pavetta barnesii Elmer ex. Merr. (Pavetteae), and Psychotria species collected were previously assessed Kanapia cf. monstrosum (A. Rich.) Arriola & Alejandro by Sohmer and Davis (2007) but recently, Biag and (Vanguerieae) (Figure 6) – occurred as singular individuals Alejandro (2020) placed each of the species under the Data in the surveyed sites. Except for C. membranifolia and P. Deficient (DD) category due to the lack of distributional barnesii, all the other species are Philippine endemics. data and other information required to assess a species’ Greeniopsis discolor was recorded in Divilacan, conservation status. specifically near a road, but the area in which the species was found is filled with water. This proves that its The data obtained suggest that the NSMNP is indeed distribution has expanded since this has been documented worth protecting and worth conserving. It houses several only in Palanan (Alejandro et al. 2010; Uy and Alejandro Philippine endemics and those with restricted distributions 2012). This species is distinguishable from other species or the so-called narrow endemic species. of Greeniopsis through the wooly hairs on the abaxial side Continuous floristic surveys in the NSMNP would of its leaves, as described by Alejandro et al. (2010) – an open doors for the discovery of more species. Most of exact observation made with our specimen. Thriving in the species collected are not yet evaluated in terms of the lowland forest of Palanan, Kanapia cf. monstrosum their conservation status based on IUCN. This implies is a shrub with leaves that are elliptic to ovate, about insufficient information about these species due to the 12–16.5 × 5.3–7.7 cm in measurement, chartaceous, and limited fieldwork conducted in the country. Therefore, with adaxial and abaxial sides that are pale green and this study's results will serve as baseline information in dark green, respectively. Stipules are connate, with each coming up with each species' recent conservation status. measuring 10 mm in length. Ophiorrhiza oblongifolia – found in Cabagan, a non-coastal area – was having lanceolate leaves of unequal sizes (about 2.2–6.0 × 1.0–2.7 cm) that are CONCLUSION greenish to reddish when dry. Antirhea benguetensis The NSMNP has proven that it keeps the natural treasures is characteristically unique for the densely pubescent based on the results of this floristic study. The 52 species vegetative and reproductive parts. The leaf blades are collected belonging to 23 genera representing 15 tribes elliptic, 5.6–11 × 2.6–6.5 cm in measurement, chartaceous, is also a manifestation that the park contributes greatly and with a rounded base and acuminate apex. Stipules are to the Philippine biodiversity. The number of species valvate to deltate, each measuring 4.5 × 11 mm. Fruits are comprises about 9.72% of the total number of Rubiaceae ellipsoid and are about 7–8 mm long. species in the country. The municipality covered by the park, which gave the highest record in terms of species Endemicity and Conservation Status richness, is Palanan. In total, 31 species were documented In the current study, results show that 31 endemic as Philippine endemics, of which two are said to be NES, species can be found in the natural park, with the which are also assessed as CR. The park, being a host to municipality of Palanan harboring the most number the three Philippine endemic genera, is also great proof with 15 endemic species. The presence of Psychotria of how rich the area is. pubilimba and Villaria fasciculiflora demonstrates It is a fact that there is still an occurrence of forest that the said park also hosts NES, of which both are degradation in this natural park, particularly in Palanan represented by very few individuals only. The former where marks of illegal and unsustainable logging and is confined only in Isabela and Cagayan provinces, slash-and-burn farming were evident. These human- with the latter in the provinces of Isabela and Rizal. induced activities are combined with the occurrence of Interestingly, three genera endemic to the Philippines strong typhoons in the area. Such destruction must be coupled with a lot of botanical surveys. In so doing, the

917 Philippine Journal of Science Biag and Alejandro: Rubiaceae Flora of NSMNP, Vol. 150 No. 3, June 2021 Luzon, Philippines chance of discovering the undiscovered, the unidentified, ARRIOLA AH, ALEJANDRO GJD. 2013. A new and the unnamed species is higher before them meeting species of Psydrax (Vanguerieae, Rubiaceae) from their ultimate end. The information on the endemism and Luzon, Philippines. Phytotaxa. doi: 10.11646/ conservation status of the species documented in this study phytotaxa.149.1.4. will be of immense contribution to the database this PA ARRIOLA AH, ALEJANDRO GJD. 2015. A new may have. It will also dictate what must be done for these species of Discospermum (Coffeeae, Rubiaceae) from species to perpetuate. This study highly recommends that Luzon, Philippines including its conservation status. the other municipalities covered by the NSMNP will also Phytotaxa. doi: 10.11646/phytotaxa.206.1.7. be considered for floristic surveys. BALATIBAT JB. 2008. Wildlife diversity studies and conservation efforts in the Philippines. Forest Sci Technol 4(1): 1–4. doi: 10.1080/21580103.2008.9656331. ACKNOWLEDGMENTS BANAG-MORAN CI, THRIPPLETON T, ALEJANDRO The first author is grateful to the Commission on Higher GJD, REINEKING B, LIEDE-SCHUMANN S. 2015. Education and the Cagayan State University for the Bioclimatic niches of selected endemic Ixora species scholarship grant. Both authors are likewise thankful to the on the Philippines: predicting habitat suitability due DENR Region 02 Office for granting them the gratuitous to climate change. Plant Ecol 216: 1325–1340. doi: permit that allowed them to proceed with their field works 10.1007/s11258-015-0512-6. in the national park. BANAG C, MOULY A, ALEJANDRO G, BREMER B, MEVE U, GRIMM G, LIEDE-SCHUMANN S. 2017. Ixora (Rubiaceae) on the Philippines – cross­ road or cradle? BMC Evol Biol 17: 131. doi: 10.1186/ REFERENCES s12862-017-0974-3. ALEJANDRO GJD, LIEDE S. 2003. The Philippine BEENTJE H. 2016. The Kew Plant Glossary: an Rubiaceae genera. Updated synopsis in INTKEY illustrated dictionary of plant terms. Richmond: Royal databases of the DELTA system. Blumea 48: 261–277. Botanic Gardens, Kew. doi: 10.3767/000651903X674964. BIAG RD, ALEJANDRO GJD. 2020. Rediscovery of ALEJANDRO GJD, MEVE U, UY M, MOULY A, Psychotria species, subspecies and varieties collected THIV M, LIEDE-SCHUMANN S. 2010. Molecular in the 1990s and new records of Antirhea benguetensis support of the classification of Greeniopsis Merr. in (Elmer) Valeton and Ixora longifolia Smith (Rubiaceae) Aleisanthieae (Rubiaceae), with a revision of the genus. in Northern Sierra Madre Natural Park, Luzon, Taxon 59(5): 1547–1564. Philippines. Biodiversitas 21(10): 4524–4535. ALEJANDRO GJD, MEVE U, MOULY A, THIV M, [BMB] Biodiversity Management Bureau. 2016. Status LIEDE-SCHUMANN S. 2011. Molecular phylogeny of the Philippine Biodiversity. BMB Official Website. and taxonomic revision of the Philippine endemic Retrieved from https://bmb.gov.ph/388-protection- Villaria Rolfe (Rubiaceae). Plant Syst Evol 296: 1–20. and-conservation-of-wildlife/facts-and-figures/786- doi 10.1007/s00606-011-0472-9. status-of-the-philippine-biodiversity. ALEJANDRO GJD. 2015. A new endemic species of CO LL, LA FRANKIE JV, LAGUNZAD DA, PASION Philippine Hedyotis L. (Rubiaceae) named after Pope KAC, CONSUNJI HT, BARTOLOME NA, YAP SL, Francis. The Antoninus Journal 1: 74–78. MOLINA JE, TONGCO MAC, FERRERAS UF, ALI SJ, ROBBRECHT E. 1991. Remarks on the tropical Asian DAVIES SJ, ASHTON PS. 2006. Forest Trees of and Australian taxa included in the Diplospora or Palanan, Philippines: A Study in Population Ecology. (Rubiaceae--Gardenieae). Blumea 35: 279–305. Center for Tropical Forest Science. ANI PAB, CASTILLO MB. 2020. Revisiting the State of DAVIS AP, GOVAERTS R, BRIDSON DM, RUHSAM Philippine Biodiversity and the Legislation on Access M, MOAT J, BRUMMIT N. 2009. A global assessment and Benefit-sharing. Food and Fertilizer Technology of distribution, diversity, endemism and taxonomic Center for the Asian and Pacific Region (FFTC-AP). effort in the Rubiaceae. Ann. Missouri Bot. Gard. 96: 68–78. ARRIOLA AH, PARAGUISON LD, ALEJANDRO GJD. 2016. Kanapia (Vanguerieae): a new endemic genus of Philippine Rubiaceae Plant Syst Evol. doi: 10.1007/ s00606-016-1307-5.

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APPENDIX Neonauclea media. Mt. Isarog, Naga City, Prov., 31 May 1992, Barbon & al.8092 (L). List of Herbarium Specimens Examined Uncaria perrottetii. Mt. Intseg Camp, Brgy. Kimbolo, Greeniopsis discolor. Ermita Hill, Baler, Prov., Banaue, , 04 Aug. 1992, Reynoso & al. 7090 Feb 2010, Alejandro 25029 (L, PNH, US, USTH). (L). , 26 Nov 1975, Iwatsuki & al. Isabela Prov., Palanan, Diguyo, 23 Apr 1991, 104 (L). Ridsdale & al. 122 (A, K, L), Digallorin, Divinisa Hypobathrum glomeratum. Angat, , 13 Apr campsite, 08 Apr 1992, Ridsdale & Baquiran 424 1918, Merrill 688 (US). So. Cabuluan,Dibuluan, San (A, EIC-ISU, L). Mariano, Isabela, Mar 2000, PLAN International- Diplospora fasciculiflora. Palanan, Isabela Prov., Philippines 1212 (EIC-ISU). 23 Apr 1991, Ridsdale & al. 127 (EIC-ISU, L). Villaria fasciculiflora. San Mariano, Dibuluan Isabela, Pinamalayan, Mindoro Jun 1922, Ramos 40888 25 Mar 1926, Ramos & Edano 46775 (K, US). (PNH, US). Ophiorrhiza oblongifolia. Mt. Makiling, Los Banos, Discospermum whitfordii. Prov., Mariveles, Jun-Jul 1917, 17584 (PNH, US). Jan 1903, R.S. Willams 400 (K); Bataan Prov., Pavetta barnesii. Mt. Mariveles, Bataan, Nov 1904, Mariveles, May 1904, H.N. Whitford 202 (K, P). ADE Elmer 6788 (K, PNH); Jul 1904, Bordon 1369 Antirhea benguetensis. Mt. Susong-Dalaga, Rizal (K, PNH). So. Divinisa, Brgy Didadungan, Palanan, Prov., Aug 1917, Ramos & Edano 29343 (US). Isabela, PLAN International Phils. 2921 (EIC-ISU). Rizal Prov., Sep 1905, Ahern’s Collector 3302 (US). Chassalia membranifolia. Lucban, Tayabas, 3 May Mt. Umingan, Prov., Aug-Sep 1916, 1907, ADE Elmer 9185 (K, PNH). Ramos & Edano 26368 (MNHN). Psychotria gitingensis. Sibuyan Island, Punong Mt., on Ixora confertiflora. Dinagat Island, May 1919, Ramos Jaosan-Punong River trail, 19 May 1987, Sohmer & Pascasio 35206 (NY). 12393 (BISH); Sibuyan Island, Mt. Giting-giting Ixora leucocarpa. , , Mar on a forested ridge, May 1910, Elmer 12439 (GH); 1911, Elmer 12894 (NY). Island, Buenavista-Bo. Tubod, Sulit PNH Ixora salicifolia. , Prov., 11 Aug 1992, 11727 (A, K, L). Barbon & al. 8582 (L, PNH). Antilao River, Ormoc, Psychotria nitens Isabela Province, Mt. Moises, Mar 12 Mar 1950, Edano 11858 (A, PNH), 1926, Ramos and Edano 47265 (US); Tayabas, Mt. Ixora longifolia. Province, 2 Mar 1994, Binuang, May 1917, Ramos and Edano 28615 (US). Barbon & al. 12527 (L); Province, Camp 7 Psychotria pilosella subsp. erythrotricha var. (lower), Minglanilla (ERDS), 14 Jun 1997, Gaerlan erythrotricha Province, Bicol & Reynoso 20383 (K, L). National Park, 18 May 1949, E. Canicosa 9763 Prismatomeris brachypus. Tungao So., San Mateo, (BISH); Leyte Province, 15 September 1913, C.A. , Prov., 30 May-26 Jun 1961, Wenzel 530 (US); Samar Province, Mt. Sohotan, Mendoza, 42409 (PNH, US). San Mariano, Isabela Babasian Na Daku River, Apr 1970, Gutierrez et Prov., 28 Feb 1991, Co 3350 (US). Surigao del Sur, al. 117680 (L). 12 May 1975, University of San Carlos 785 (L). Psychotria pubilimba Palanan, Isabela Province, Mussaenda philippica var. philippica. Bicol Nat. Sierra Madre Mountains, 11 May 1961, Gutierrez Park, Camarines Norte, Canicosa 9765 (PNH). 18259 (L). Carambola, Pili, Camarines Sur, Convocar 2945 Psychotria reynosoi Isabela Province, Mt. Moises, Mar (A, MO, PNH). 1926, Ramos and Edano 47288 (US); Tayabas, Mt. Mussaenda philippica var. pubescens. Butuan, San Binuang, May 1917, Ramos and Edano 28568 (US). Mateo Bo., Tungao So., , Mendoza Psychotria rubiginosa Bataan Province, Mt. Palacio, 42193 (US). , Ramos 14604 (US). Mt. Dec 1947, Edano 4124 (PNH). Mayo, , Edano 11384 (PNH). Psychotria subsessiliflora var. carinata San Mariano, Neonauclea reticulata. , 21 May 1986, Isabela Province, Sierra Madre Mountains, Apr- Ridsdlae & Reynoso 1366 (L). Penablanca, May 1961, H.G. Gutierrez 78165 (L); Casiguran, Cagayan Prov., 21 Jan 1994, Reynoso & al. 11799 Tayabas, May-Jun 1925, Ramos and Edano 45278 (L). (BISH).

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Psychotria tayabensis var. euphlebia Sangcad, Palanan, Isabela Province, 11 May 1961, H. Gutierrez 78268 (L); Alabat Island, Sep-Oct 1926, Ramos and Edano 48228 (US). Uncaria cordata. Mt. Makiling, Laguna, 24 Mar 2017, Atienza & al. 013921 (USTH). Uncaria longiflora. Mt. Mingan, Aurora, 24 Mar 2017, Olivar & al. 013920 (USTH). Uncaria lanosa. Mt. Bulusan, Bicol, 24 Mar 2017, Olivar & al. 013923 (USTH). Hedyotis bambusetorum. Palawan, 23 Apr 1984, Ridsdale 1522 (L). Taytay, Palawan, Apr 1913, Merrill 9214 (US). Hedyotis simplex. , 11 Dec 1917, Ramos 30242 (HNMN). Malangas, Zamboanga, Oct-Nov 1919, Ramos & Edano 37094 (L). Spermacoce remota. Mt. Pao, Adams, Ilocos Norte, 16 Apr 2015, Braganza & al. 15839 (USTH). Praravinia sablanensis. Palanan, Isabela 1997-2003, Co & al. 16867 (PUH). Mt. Angilog, Rizal Prov., Apr 1922, Ramos 40792 (PNH, US). Praravinia loheri. So. Kanauli, Brgy. St. Jacinta, Palanan, Isabela, PLAN International Phils.1409 (EIC-ISU). Mt. Masingit, , , Feb 1920, Ramos & Edano 37507 (PNH, US). Praravinia everettii. Cabagan, Isabela, PLAN International Phils. 855 (EIC-ISU). Mt. Silay, , May 1906, H.N. Whitford 1525 (PNH, US). Kanapia monstrosa. Mindoro, Cuming 1554 (MO).

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