1 Philippine Amphibians and Reptiles: 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 frog (Barbourula 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 Palawan. It is one of the only two known Australian faunal zones, the herpetofauna of this largely species of this genus. Frogs 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 animal protein. SPECIES DIVERSITY AND ENDEMISM Reptiles Amphibians The reptilian fauna is composed of terrestrial turtles (6 species), marine turtles (5 species), lizards 6he Philippine amphibian fauna is comprised (124 species), terrestrial snakes (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 animals. 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, Culion, 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
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