doi:10.29203/ka.2020.500 ORIGINAL Karstenia, Volume 58 (2020), Issue 2, pages 275–291 RESEARCH www.karstenia.fi A comparative diversity study of myxomycetes in the lowland forests of Mt. Malasimbo and Mt. Siburan, Mindoro Island, Philippines Melissa H. Pecundo1,3, Nikki Heherson A. Dagamac2,4, and Thomas Edison E. dela Cruz1,2,3* Abstract 1 The Graduate School Million years ago, the island of Mindoro separated 2 Department of Biological Sciences, College of Science from mainland Asia. Its geologic origin led to many 3 Fungal Biodiversity, Ecogenomics and Systematics species distinct from Asia and the other islands of (FBeS) Group, Research Center for the Natural and Applied Sciences, University of Santo Tomas, España the Philippines. In this study, two lowland mountain Blvd. 1008 Manila, Philippines forests – Mt. Malasimbo (MM) in Puerto Galera, Ori- 4 Institute of Botany and Landscape Ecology, University ental Mindoro, and Mt. Siburan (MS) in Sablayan, of Greifswald, Soldmannstr. 15, D-17489, Greifswald, Occidental Mindoro – were surveyed for myxomy- Germany cetes. The combined opportunistic sampling in the field and the setting up of 1,260 moist chamber * Corresponding author: cultures retrieved a total of 1,007 fruiting body col- [email protected] lections representing 50 species from 17 genera. A relatively higher number of taxa (49 species) was re- Keywords: Biosphere reserve, Ecotourism, Forest corded in Mt. Siburan than in Mt. Malasimbo (36). watershed, Plasmodial slime mold, UNESCO Man and Seventeen species were classified as rare with only Biosphere Programme four taxa that were widely distributed in both study Article info: sites, namely, Arcyria cinerea, Perichaena pedata, Received: 03 July 2020 Diderma hemisphaericum, and Lamproderma scin- Accepted: 05 October 2020 tillans. Higher species diversity and richness were Published online: 22 November 2020 noted for Mt. Siburan than Mt. Malasimbo, but a Corresponding Editor: Oleg Shchepin clear similarity in species composition (CC = 0.80) 276 and abundance (PS = 0.72) can be observed between mountain forest is Mt. Malasimbo which towers the forest sites. This suggest that lowland natural forest Puerto Galera shore, a profound coastal scenery in habitats of Mt. Malasimbo and Mt. Siburan are hot- Mindoro that is threatened due to unregulated tour- spots of myxomycete diversity. This research repre- ism activities and commercial logging. Four dec- sents the most comprehensive survey of myxomy- ades ago, these activities led to the peninsula being cetes in Mindoro Island. declared as a biosphere reserve under the United Nations Educational, Scientific, and Cultural Organ- ization (UNESCO) - Man and Biosphere Programme to protect Puerto Galera’s marine and terrestrial biodiversity. Another lowland forest is the Mt. Sibu- Introduction ran in Sablayan Watershed Forest Reserve in the southwestern part of Mindoro where the forest has Mindoro Island in Southwest of Luzon was rifted been selected as an important biodiversity conser- from the Asian mainland millions of years ago. To- vation area by Haribon Foundation and BirdLife gether with Palawan and Busuanga, it was believed International. Mt. Malasimbo and Mt. Siburan were that Mindoro was once part of the North Palawan just among the identified sites as highly critical un- Block, a micro-continent that was separated when der conservation priorities. In terms of vegetation, the South China Sea marginal basin opened dur- Mt. Siburan apparently displayed richer and more ing the mid-Oligocene (Sarewitz & Karig 1986). healthy vegetation than Mt. Malasimbo. The former In addition, the variations in geographical attrib- is the largest and the only one left with intact low- utes of Mindoro’s interior have suggested that the land forest in Mindoro while the latter has a logged- south-western portion of the island has a separate over secondary growth forest with remnants of the origin (Hamilton, 1989). Owing to its geologic origin, primary lowland dipterocarp forest. Myxomycetes the island is considered as a distinct biogeographical have also been previously reported in Mindoro Is- region in the Philippine archipelago which strongly land in coastal and community forests of Puerto influenced the evolution of present biological diver- Galera with 42 species belonging to 16 genera (Dag- sity. In fact, Mindoro ranks as the seventh largest is- amac et al. 2015) and in the island of Lubang with land and one of the 117 key conservation sites in the 44 species and 13 genera (Macabago et al. 2016). Philippines (De Alban et al. 2004). Based on the pre- Lubang is a distinct island near the main island of vious report, a total of 941 plant species under 179 Mindoro, exactly 136 km away, albeit politically list- families occur on Mindoro, with many notable plant ed under the province of Occidental Mindoro. species that are unique or endemic to the island in- Myxomycetes are eukaryotic protists charac- cluding Pinus merkusii Jungh & de Vriese, Calamus terized by uninucleated amoeba, multinucleated mindorensis Becc., Centrolepis philippinensis Merr., plasmodium, and fungal-like fruiting bodies which Elatostema halconense C.B. Rob., Mezoneuron min- produces spore mass (Clark & Haskins 2016). The dorensis Merr., Leucosyke mindorensis C.B. Rob., and number of studies about the distribution of myxo- Strobilanthes halconensis Merr (Villanueva & Buot mycetes has been increasing during the last years 2015). This makes the geographically isolated island in the tropical Philippines as surveys of enormous an ideal site to study other organisms such as the eu- habitat types [grasslands (Carascal et al. 2017), ag- karyotic plasmodial slime molds or myxomycetes. ricultural lands (Alfaro et al. 2015, Redeña-Santos et The interior structure of the island is basically al. 2017)] and intensive regional surveys [Neotropics rugged with vegetation types ranging from diptero- vs Paleotropics (Dagamac et al. 2017a)] were con- carp (at 500 meters above sea level, masl) to mossy ducted. The country has also shown a great increase forests (at 1,000 masl) to subalpine forests (2,470– in the number of newly recorded taxa as indicated 2,587 masl) (Merill 1907, Mandia 2001). Here, we in the study of Mt. Arayat in Pampanga (5 records chose two lowland mountain forests from the east- new to the country, Dagamac et al. 2011), Lubang ern and western sides of the island. The first lowland Island (7 records, Macabago et al. 2012), Hundred 277 Islands in Pangasinan (3 records, Kuhn et al. 2013), um Novozh. & D.W. Mitch. (Novozhilov et al. 2014), Bataan, Cavite and Zambales (19 records, dela Cruz and Perichaena echinolophospora Novozh. & S.L. et al. 2014), the Bicol peninsula (8 records, Dagamac Stephenson (Novozhilov & Stephenson 2015)]. To et al. 2017b), Bohol Islands (8 records, Macabago et contribute to this growing trend in myxomycete dis- al. 2017), and Laguna province (1 record, Bernardo tribution studies, the primary objective of the pres- et al. 2018). One species new to science, Craterium ent study was to investigate the assemblages of myx- retisporum G. Moreno, D.W. Mitch. & S.L. Stephen- omycetes in two lowland forests of Mindoro Island. son was described from specimens collected in In addition, the possible influence of rainfall events Anda Island, Pangasinan (Moreno et al. 2009). Fur- during the field sampling, vegetation composition, thermore, the first local habitat suitability modeling and/or forest disturbance in the study area on the using the tropical cosmopolitan species Diderma assemblages of myxomycetes was evaluated. hemisphaericum (Bull) Hornem has demonstrated range expansion of the species on various climate change scenarios (Almadrones-Reyes & Dagamac 2018). Recently, the Paleotropical Asia-Pacific zone had also gained its momentum of more exhaus- Materials and Methods tive myxomycete surveys wherein Southeast Asian countries like Vietnam (174 species, Nguyen et al. 2019, Novozhilov et al. 2020) and Thailand (145 spe- Sampling expeditions and study sites cies, Dagamac et al. 2017a) had shown an increased number of recorded species and identification of Two sampling expeditions with rainfall variations new species [Comatricha spinispora Novozh. et D.W. were conducted in the study areas, one in October Mitch. (Novozhilov & Mitchell 2014), Diderma cat- 2014 (end of rainy season) and the other in June tiense Novozh. & D.W. Mitch. and D. pseudotestace- 2015 (onset of rainy season). Mindoro Island, where Figure 1. Map of the study sites. A: Map of the entire Mindoro Island, displaying the plotted collecting points (generated using the Quantum GIS, v1.8) and view B: of Mt. Malasimbo (black arrow: peak) in Puerto Galera, Oriental Mindoro and C: Mt. Siburan, Sablayan, Occidental Mindoro 278 Table 1. Description and geographic coordinates of the two lowland forests in Mindoro Island. Elev. Dominant plant Climate Average rainfall Forest site Lat. Long. (masl) spp. type (Oct 2014) Jun (2015) Mt. N13°28’30” E120°54’59” 702 Dipterocarpus Malasimbo spp, Ficus, Type III 300 mm 268 mm (MM) Cleidon, Aglaia Mt. Siburan N12°49’40.7” E120°54’57.1” 333 Dipterocarpus, (MS) Ficus, Type I 201 mm 131 mm Clerodendrum, Ixora, Lunasia the collecting localities were identified, is bound- On the other hand, Mt. Siburan is located near ed on the north by the Verde Island passage and is the Sablayan Prison and Penal Farm and is part of about 123 km south of Manila. Two forest sites: Mt the Sablayan Watershed Forest Reserve. The low- Malasimbo in Puerto Galera, Oriental Mindoro, and land forest of Mt. Siburan comprises almost half of Mt. Siburan in Sablayan, Occidental Mindoro, were the total forest cover of Mindoro. Some of the key chosen in this study (Figure 1). Generally, both are- plant species in this forest include Shorea contorta as were characterized as lowland mountain forests Vidal (White Lauan) and Calamus spp. (Rattan) (De dominated by dipterocarp trees, e.g. Shorea spp., Dip- Alban et al. 2004). It has a Type I climate with two terocarpus gracilis Blume, D. grandiflorusBlanco, and pronounced seasons, dry from November to April D.