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Philippine and : An Overview of Species Diversity, Biogeography, and Conservation

Arvin C. Diesmos , Rafe M. Brown , Angel C. Alcala!, Rogelio V. Sison", Leticia E. Afuang#, and Genevieve V. A. Gee$

Biological Sciences Department, College of Science, De La Salle University-Dasmariñas, 4115 Dasmariñas, Cavite, Philippines; Section of Integrative Biology and Texas Memorial Museum, University of Texas, Austin, TX 78712, USA; !Silliman University- Angelo King Center for Research and Environmental Management, SU Marine Laboratory, 6200 Dumaguete City, Philippines; "Herpetology Section, Zoology Division, Philippine National Museum, Padre Burgos Street, 1000 Manila, Philippines; #Conservation International-Philippines, Philam Homes, 1104 Quezon City, Philippines; $Haribon Foundation, Teachers Village, 1101 Quezon City, Philippines

6he Philippine Archipelago is home to a spec- flat-headed ( busuangensis), a fully tacular and diverse assemblage of amphibians and rep- aquatic species inhabiting unpolluted mountain streams tiles. Situated at the interface between the Oriental and and rivers of . It is one of the only two known Australian faunal zones, the herpetofauna of this largely species of this . of the genus Platymantis oceanic island archipelago has captured the attention are the most diverse; the number of Philippine species and imagination of systematists and biogeographers for currently stands at 26 but dozens of newly discovered nearly 200 years. Previously thought of as having a species are still awaiting description. depauperate herpetofauna, the Philippine archipelago is now recognized as one of the most important center The fauna includes four species of frogs that have of herpetofaunal diversity in Southeast Asia. Informa- been introduced by man either intentionally (Bufo tion generated from recent field surveys coupled with marinus, Hoplobatrachus rugulosus, Rana catesbeiana) analyses of available data on diversity, points to over- or inadvertently (Rana erythraea). Bufo marinus was whelming evidence that the Philippine herpetofauna introduced supposedly to control populations of sugar is far richer, the levels of endemicity are much higher, cane beetles while Hoplobatrachus rugulosus and Rana and the evolutionary history is far more complex than catesbeiana were introduced for the purpose of farm- have been assumed. ing as sources of protein.

SPECIES DIVERSITY AND ENDEMISM Reptiles

Amphibians The reptilian fauna is composed of terrestrial turtles (6 species), marine turtles (5 species), lizards 6he Philippine fauna is comprised (124 species), terrestrial (106 species), marine of caecilians (Gymnophiona) and frogs (Anura). The snakes (15 species), and crocodiles (2 species). This caecilians are represented by 2 genera and the anurans diverse and complex group is divided into 17 families are represented by at least 22 genera. At present, we and is represented by at least 83 genera. A total of 258 recognize a total of 101 species comprised of 3 species species occur, 170 species or 66% are endemic to the of caecilians and 98 species of frogs. There are no known Philippines (Table 2). endemic genera, however, endemicity at the species level is exceptionally high: 78 of the 101 species (77%) are Five genera are presently recognized as limited to found only in the Philippines (Table 1). the Philippines: Pseudogekko, Parvoscincus, Cyclocorus, Hologerrhum, and Myersophis. Caecilians are worm-like, limbless, and are among Myersophis is monospecific and is known only from the ancient living amphibians. In the Philippines, they the highlands of the Central Cordilleras of Luzon. Ten are restricted to the western and southern islands, known of the 40 or so species of Draco, the flying lizards of thus far from very few localities on Palawan, Basilan, Southeast Asia, are endemic to the Philippines. Four- and Mindanao. The natural history of the three Phil- teen of the 15 species of Brachymeles are likewise con- ippine caecilians is virtually unknown primarily due to fined to the Philippines, with the remaining species the secretive behavior of these . Frogs are found known only from Borneo. This genus of legless skinks in most of the islands of the archipelago. The most also exhibits one of the most spectacular Philippine primitive species of frog in the country is the Palawan radiations. The lizard genus Sphenomorphus is the most Diesmos, et. al., 2002 2 speciose taxon with 25 species, all of which are en- · Mindanao PAIC: Mindanao, Samar, demic to the Philippines. Among the snakes, blind Maripipi, Biliran, Leyte, Bohol, Dinagat, snakes of the genus Typhlops are the most diverse with Siargao, Basilan, and adjacent small islands 16 species. They are also known to be among the most · Sulu PAIC: Tawitawi, Jolo, and adjacent small ancient snakes in the world. islands

BIOGEOGRAPHY While it is to be expected that aggregate islands )n understanding of the geographical distribu- within a PAIC share a high percentage of faunal ele- tion of the major groups of amphibians and reptiles ments in common, there are many instances wherein has been discussed in detail from the previous taxo- these islands contain endemic species of their own. A nomic and zoogeographic summaries of past workers. fine example is the islands of Panay, Negros, and Cebu These scholarly works ably discussed dispersal routes in the Visayas PAIC. Panay has at least 4 endemic spe- of the fauna, zoogeographical relationships, possible cies (Platymantis panayensis, Parvoscincus sisoni, land-bridge connections, and have also identified fau- Hologerrhum dermali, Pseudorabdion talonuran) that nal subdivisions (or biogeographic regions) of the Phil- have never been found on Cebu and on Negros, con- ippine herpetofauna. The herpetofaunal regions that sidering that the herpetofauna of the latter island is the have been identified range from two to five. best studied in the Philippines. On the other hand, at least 4 species (Platymantis hazelae, Platymantis To a large extent, the biogeography of the Phil- spelaeus, Lipinia rabori, Typhlops canlaonensis) are ippine herpetofauna shows a pattern that is similar to confined to Negros while 2 species that are present on that exhibited by terrestrial birds and non-volant mam- Cebu (Brachymeles cebuensis, Typhlops hypogius) are mals. These biogeographic regions are centers of bio- not known to occur in either Negros or Panay. logical endemism that are concordant with the geo- logic formation of the Philippine archipelago during Data from recent studies suggest that amphib- the Pleistocene Epoch. During the great ice ages of the ians and reptiles have a tendency towards a finer-scale Pleistocene, sea levels were reduced such that islands isolation and differentiation thereby making them ap- that were separated by sea 120 meters deep were con- propriate organisms to use in identifying sub-centers nected. Here, we refer to these ice-age island amal- of endemism. For instance, three species of Platymantis gamations as Pleistocene aggregate island complexes, frogs on Mt. Banahao (an isolated volcano on the is- or PAIC. land of Luzon) have a spatial distribution of less than We recognize 9 herpetofaunal regions in the Phil- 70 square kilometers, are confined to the montane el- ippines albeit arbitrarily. These subdivisions could be- evations on that mountain, and are found only on a come modified further as our knowledge of species dis- single island. This fine-scaled distribution pattern is tributions, faunal boundaries, and taxonomic and phy- particularly exhibited by diminutive frogs, snakes, and logenetic relationships of the herpetofauna improve. lizards and is repeated in many other isolated moun- The herpetofaunal regions are as follows: tains and mountain ranges in the Philippines.

· Batanes PAIC: composed of the islands of An understanding of mid- to late-Pleistocene Batan, Itbayat, Sabtang, and several small geology is the key to appreciating the distribution of adjacent islands life in the Philippines and most importantly, in formu- · Babuyanes PAIC: Babuyan, Calayan, lating effective conservation strategies. The recognition Dalupiri, Camiguin, Fuga, and adjacent of these Pleistocene aggregate island complexes is the small islands appropriate framework for appreciation of Philippine · Luzon PAIC: Luzon, Polillo, Catanduanes, biodiversity on all levels, for it is the unique geological Marinduque, and adjacent small islands history of the islands that unites the evolutionary his- · Mindoro PAIC: Mindoro, Ilin, Semirara, and tories of Philippine biodiversity. adjacent small islands · Romblon PAIC: Romblon, Tablas, Sibuyan CONSERVATION · Visayas PAIC: Panay, Guimaras, Negros, Cebu, Masbate, and adjacent small islands 6he most recent publication of the IUCN · Palawan PAIC: Palawan, Busuanga, listed 32 threatened amphibians and reptiles in the Calamian, , Balabac, and adjacent Philippines, and another 10 species that have lower small islands threat categories (Table 3). The critically endangered

Philippine Amphibians and Reptiles: An Overview of Species Diversity, Biogeography, and Conservation 3 taxa include 7 species of Platymantis frogs, 1 marine are killed by people), could exact a heavy toll on the turtle, 1 freshwater turtle, and the endemic Philippine population of rare species. This matter needs to be in- crocodile. Amphibians dominate the list while only 9 vestigated. species are reptiles. While a good number of species in this list are genuinely threatened with extinction, re- On the bright side, there are positive cases in the sults from recent faunal inventories prove that some effort to conserve the herpetofauna. Among the most species in the list apparently have stable populations celebrated include the conservation programs for ma- and secured habitats. It is clear that the status of the rine turtles and crocodiles. In close cooperation with species in such listings need to be re-assessed periodi- local and international agencies, peoples' organizations, cally. The general lack of data on the ecology, distribu- and local communities, the Philippine government has tion, population trends, and abundance of more than successfully established sanctuaries, captive-breeding 85% of the amphibian fauna and over 90% of the rep- facilities, and research and education programs to pro- tilian fauna impedes a more accurate assessment of their tect and conserve these species. Meanwhile, a commu- conservation status. nity based conservation program has been initiated by the Silliman University to save the Negros cave frog Although no cases of extinction of Philippine Platymantis spelaeus (listed as a critically endangered amphibians or reptiles have been documented, the large- species) and its habitat (limestone forests and caves). scale destruction of the lowland forest-now almost com- pletely gone in many parts of the Philippines-imply The designation of remaining tracts of forests and that part of the diversity may have already been lost other habitats as protected areas (especially under the even before they were described by science. Similarly, re-developed National Integrated Protected Areas Sys- cases of declines in amphibian populations have not tem) is highly encouraging and is a positive step in been documented in the Philippines. One important conserving Philippine biodiversity as a whole. One of reason is the lack of long-term population studies be- the major challenges facing the protected areas system ing conducted on the islands, save for a few attempts is developing initiatives that will provide needed re- on Negros. sources and infrastructures to ensure the protection of the areas. Most of these protected areas lack detailed The most immediate and clear threat to the fauna faunal inventories, habitat studies, or analyses of hu- is . The clearance and fragmenta- man impacts, rendering difficulties in the formulation tion of the lowland dipterocarp forest and even the lower of conservation strategies. However, these gaps cannot montane forest affect more than 85% of the fauna. In be used as an excuse for inaction. the light of recent studies showing that the peak of diversity of forest frogs is found at the montane forest, ANALYSIS the common practice of converting vast tracts of mon- tane forest into large-scale agricultural plantations (a )n estimated total of 359 species of amphib- popular example is the so called "vegetable bowl" in ians and reptiles is now known in the Philippines mak- the Cordilleras of northern Luzon) proves to be detri- ing the herpetofauna the second most diverse verte- mental to many endemic species. brate group in the Philippines. Of the 359 species, 246 (68%) are endemic to the country-currently the high- Other important herpetofaunal habitats that are est known percentage among the vertebrates. The rate also being destroyed at alarming rates include marine of discovery of new species is likewise the highest: a reefs, beaches, natural lakes and ponds, limestone caves, total of 36 new species (20 frogs, 8 lizards, and 8 snakes), mangroves, and swamps. The siltation of mountain roughly 10% of the total herpetofauna, has been dis- streams and rivers due to forest clearance threatens the covered in the last twelve years. For its size, the Philip- existence of many species and their larvae that inhabit pines has a particularly rich herpetofauna. As a point these freshwater ecosystems. of comparison, the island of Borneo, which is 2.5 times larger than the Philippines, has about 140 species of Other big threats to the fauna are: 1) pollution frogs. The Philippines has nearly 100 species while of streams and rivers from mine tailings, pesticide and many more new species are being discovered every year. herbicide run-offs, 2) over-hunting (especially of moni- tor lizards), 3) the introduction of alien and invasive The exact total number of species of Philip- species, and 4) the flourishing, unregulated pet and pine amphibians and reptiles still remains uncertain leather trade. In addition to these threats, we suspect up to this point. The gaps in knowledge on the sys- that persecution and the unnecessary killing of ani- tematics of the herpetofauna need to be addressed first mals, most especially of reptiles (for instance, all snakes

Diesmos, et. al., 2002 4 before a satisfactory estimate of the diversity is reached. Among the most pressing issues that need to be ad- Acknowledgement and Contributors dressed include resolving the state of polytypic species and subspecies (for example, recent studies prove that A. Altamirano, P. Alviola (Nordic Agency for Devel- some nominate species are clusters of multiple species) opment and Ecology); C. Banks (Melbourne Zoo); D. and the need for taxonomic revisions of major groups. Bennet, K. Hampson (University of Oxford); E. Cañete (DENR Region IX); D. Cannatella (Texas Natural History It is certain that alpha-taxonomic studies and the revi- Collections); R. Crombie (Smithsonian Institution); E. sion of the systematics of the fauna will see an increase Curio (Philippine Endemic Species Conservation Project); in the number of recognized species. In addition to C. Custodio, R. De Veyra, M. Mendoza (PAWB), J. Ferner, these are the many new species that continue to be R. Kennedy (Cincinnati Museum of Natural History); C. discovered from largely unexplored areas. In fact, we Dolino, P. Cariño (Center for Tropical Conservation Stud- are aware of dozens of new species (especially frogs of ies); J. Dimalibot, J. Hibaya (Palawan State University); M. the genus Platymantis) that are currently in the pro- Gaulke (Working Group for Tropical Nature and Species cess of being described. Conservation); J. Gonzalez (University of the Philippines at Los Baños); L. Liao (University of San Carlos); M. The remarkable rate of discoveries and the in- Leonida, R. Maranan, R. Lagat (De La Salle University- Dasmariñas); N. Mallari, M. Lepiten, B. Tabaranza Jr. crease in the number of publications show a height- (Haribon Foundation); A. Manamtam (CARE-Philippines); ened interest in Philippine herpetology. It is also worth M. Manuel, R. Caberoy (Philippine National Museum); J. mentioning that Filipino scientists now form a major- McGuire (Museum of Natural Science, Louisiana State ity of those working on the herpetofauna. University); P. Milan (Visayas State College of Agriculture); H. Miranda, J. Ibañez, D. Afan, G. Bueser (Philippine Eagle Since nearly 90% of the fauna are forest obli- Foundation, Inc.); J. Morrison (World Wildlife Fund-US); gates, the continued destruction of the rainforest re- P. Ong, N. Ibuna, C. Morales, L. Valenzuela, M. de Guia, mains as the biggest threat to the fauna. And for spe- M. Duya (Conservation International-Philippines); L. Tan cies with highly localized distribution patterns, a mod- (Bookmark, Inc.); M. Pedregosa (Cebu Biodiversity Con- est amount of habitat destruction may prove to be cata- servation Foundation); A. Resetar, R. Inger, L. Heaney (Field Museum); F. Romero (World Wildlife Fund-Philippines); strophic to the whole population. J. Vindum, M. Koo (California Academy of Sciences). Examples of effective conservation programs in- volving the herpetofauna are highly limited and are typically centered on large and charismatic species. However, efforts are now being initiated to undertake needed conservation programs on smaller and less-ap- pealing species.

There is a need for increased action in the field. Immediate and exhaustive faunal surveys, ecological and life history studies, and studies on the effects habi- tat fragmentation on populations are warranted in or- der to assess the conservation status most especially of rare and endemic species.

Philippine Amphibians and Reptiles: An Overview of Species Diversity, Biogeography, and Conservation 5

TABLES

Diesmos, et. al., 2002 6

Table 1. Summary of Diversity of Philippine Amphibians

Number of Number of Taxon Endemic Species Species GYMNOPHIONA (Caecilians) Icthyophiidae 3 3 ANURA (Frogs) 1 1 Megophryidae 2 2 Bufonidae 7 5 Microhylidae 12 8 Ranidae 57 4 Rhacophoridae 18 1 Total 101 78 (77%

Philippine Amphibians and Reptiles: An Overview of Species Diversity, Biogeography, and Conservation 7

Table 2. Summary of Diversity of Philippine Reptiles

Number of Number of Taxon Species Endemic Species

CHELONIA (Turtles)

Cheloniidae 4 0

Dermochelydae 1 0

Bataguridae 4 1

Trionychidae 2 0

SQUAMATA (Lizards and Snakes)

Agamidae 17 15

Gekkonidae 33 25

Dibamidae 2 0

Scincidae 69 57

Varanidae 3 1

Typhlopidae 20 18

Xenopeltidae 1 0

Boidae 1 0

Acrochordidae 1 0

Colubridae 74 44

Elapidae 21 4

Crotalidae 3 2

CROCODYLIA (Crocodiles)

Crocodylidae 2 1

Total 258 168 (65%)

Diesmos, et. al., 2002 8

Table 3. Threatened Species of Philippine Amphibians and Reptiles

Taxon IUCN Status AMPHIBIANS Philippine Discoglossid Frog Barbourula busuangensis Vulnerable Basilan Island Caecilian Icthyophis glandulosus Endangered Mindanao Island Caecilian Ichthyophis mindanaoensis Vulnerable Negros Truncate-toed Chorus Frog Kaloula conjuncta negrosesis Vulnerable Small-headed Frog Micrixalus diminutiva Vulnerable Mary’s Frog Micrixalus mariae Vulnerable Spiny Tree Frog Nyctixalus spinosus Vulnerable Camiguin Narrow-mouthed Frog Oreophryne nana Endangered Palawan Toadlet Pelophryne albotaeniata Vulnerable Bongao Tree Frog Philautus alticola Data Deficient Leyte Tree Frog Philautus leitensis Lower Risk Mottled Tree Frog Philautus poecilus Data Deficient Hazel’s Forest Frog Platymantis hazelae Critical Island Forest Frog Platymantis insulatus Critical Isarog Forest Frog Platymantis isarog Critical Smooth-skinned Forest Frog Platymantis levigatus Critical Naomi’s Forest Frog Platymantis naomii Endangered Negros Forest Frog Platymantis negrosensis Critical Panay Forest Frog Platymantis panayensis Endangered Polillo Forest Frog Platymantis polillensis Critical Pygmy Forest Frog Platymantis pygmaeus Vulnerable Rabor’s Forest Frog Platymantis rabori Vulnerable Negros Cave frog Platymantis spelaeus Critical Mt. Data Forest Frog Platymantis subterrestris Endangered Eastern Mindano Frog Rana diuata Data Deficient Swamp Frog Rana leytensis Data Deficient Giant Visayan Frog Rana magna visayana Vulnerable Sulu Frog Rana melanomenta Data Deficient Philippine Samll-disked Frog Rana parva Data Deficient Woodworth’s Frog Rana woodworthi Data Deficient

Philippine Amphibians and Reptiles: An Overview of Species Diversity, Biogeography, and Conservation 9 continuation Table 3

Taxon IUCN Status TURTLES Loggerhead Turtle Caretta caretta Endangered Green Turtle Chelonia mydas Endangered Hawksbill Turtle Eretmochelys imbricata Critical Philippine Pond Turtle Heosemys leytensis Critical Spiny Terrapin Heosemys spinosa Endangered Cantor’s Giant Softshell Turtle Pelochelys cantorii Endangered CROCODILES Philippine Crocodile Crocodylus mindorensis Critical LIZARDS Crested Lizard Hydrosaurus pustulatus Data Deficient Gray’s Monitor Lizard Varanus olivaceus Vulnerable

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Philippine Amphibians and Reptiles: An Overview of Species Diversity, Biogeography, and Conservation