Philippine Zoological Expedition 1946-1947 SYSTEMATICS AND ZOOGEOGRAPHY OF PHILIPPINE AMPHIBIA ROBERT F. INGER FIELDIANA: ZOOLOGY VOLUME 33, NUMBER 4 Published by CHICAGO NATURAL HISTORY MUSEUM JULY 23, 1954 Philippine Zoological Expedition 1946-1947 SYSTEMATICS AND ZOOGEOGRAPHY OF PHILIPPINE AMPHIBIA ROBERT F. INGER Curator, Division of Amphibians and Reptiles FIELDIANA: ZOOLOGY VOLUME 33, NUMBER 4 Published by CHICAGO NATURAL HISTORY MUSEUM JULY 23, 1954 PRINTED IN THE UNITED STATES OF AMERICA BY CHICAGO NATURAL HISTORY MUSEUM PRESS CONTENTS PAGE Introduction 185 Geographic Notes 186 Environmental Notes 188 Taxonomic Background 194 Methods and Terminology 203 Systematics 205 Key to Genera 205 Ichthyophis 207 Barbourula 209 Megophrys 213 Bufo 225 Pelophryne 233 Ansonia 239 Hyla 247 Ooeidozyga 249 Rana 259 Staurois 333 Micrixalus 344 Cornufer 348 Rhacophorus 370 Philautus 393 Chaperina 414 Kalophrynus 416 Kaloula 420 Oreophryne 445 Zoogeography 448 Introduction 448 Geologic Structure and History of the Philippine Islands 449 Composition of the Fauna 456 Reliability of Distributional Data 458 Faunal Division of the Philippine Islands 463 Faunal Relations of the Philippine Islands 463 Faunal Divisions of the Philippine Islands 468 183 184 CONTENTS PACK Dispersal of the Philippine Amphibia 471 Ecological Aspects of Dispersal 471 Modes of Dispersal 475 Dispersal Routes 485 Order and Time of Entry of Fauna 497 Summary 509 Appendix: Faunal Lists 511 References 516 Index 525 The Philippine Expedition: Amphibia INTRODUCTION Prior to the work of Taylor (1920, 1922a, b, 1923), the Philip- pine Amphibia were known only through miscellaneous papers of Giinther, Peters, Boulenger, Boettger, and Stejneger (see References). These authors received their material from such collectors as Hugh Cuming, F. Jagor, Carl Semper, A. H. Everett, 0. F. Moellendorff, and E. A. Mearns. With the exception of Cuming, who collected on most of the larger islands, each of these men worked on one or a few islands only. None of them was interested primarily in reptiles and amphibians. Cuming, for example, made a general natural history collection, Semper was primarily interested in invertebrates, and Mearns in mammals. It was not, therefore, until Taylor began his work in 1913 that a herpetologist conducted extensive field operations in the Philippines. Taylor worked on the majority of the large islands and collected in parts of some that previously had been unexplored herpetologically. In his first compilation, Taylor (1920) recognized sixty-six species, of which nineteen were described as new. Subsequent papers by Taylor (1922a, b, 1923) described twenty-two additional species. In collaboration with Noble (Taylor and Noble, 1924), he described one more species. Between 1924 and the present, no taxonomic papers devoted in large part to Philippine species have appeared, although ecological studies by Villadolid and Rosario (1930) and Cendana and Fermin (1940) have been published. The collections made by the Philippine Zoological Expedition, 1946-1947, of Chicago Natural History Museum in co-operation with the Philippine National Museum (see Hoogstraal, 1951), in- clude over 1,800 amphibians, principally from Mindanao, the Cal- amian Islands, and Palawan. Additional material from other parts of the Philippines—notably Luzon, Mindoro, Leyte, and Mactan— has been received by various American museums from members of the United States Armed Forces that were stationed in the Philip- pines during World War II. Subsequent to 1947, Mr. D. S. Rabor 185 186 FIELDIANA: ZOOLOGY, VOLUME 33 of Silliman University, Dumaguete City, Negros, has sent specimens from southern Negros to Chicago Natural History Museum. This large accumulation of fresh material presented an excellent oppor- tunity for a review of the Philippine Amphibia. It was at the suggestion of Dr. Karl P. Schmidt, Chief Curator, Department of Zoology, Chicago Natural History Museum, that this study was undertaken. It is not possible to express adequately my appreciation of his constant inspiration and helpful criticism. I am also indebted to my colleagues of the staff of Chicago Natural History Museum for advice and varied assistance; the aid of Dr. Rainer Zangerl and Messrs. D. Dwight Davis, Harry Hoogstraal, Clifford H. Pope, and Loren P. Woods was especially appreciated. Miss Margaret Bradbury, also of Chicago Natural History Museum, made all of the illustrations. Material was borrowed from various institutions, and types have been examined as far as available. For the many courtesies extended me I wish to thank the following: American Museum of Natural History, Mr. C. M. Bogert, and Mrs. M. Hecht; British Museum (Natural History), Dr. H. W. Parker, Dr. M. A. Smith, Mr. J. C. Battersby; California Academy of Sciences, Mr. J. R. Slevin; Car- negie Museum, Mr. M. G. Netting and Dr. G. L. Orton; Museum of Comparative Zoology, Messrs. Arthur Loveridge and Benjamin Shreve; Museum d'Histoire Naturelle, M. Jean Guib£; Raffles Mu- seum, Mr. M. W. F. Tweedie; University of Michigan, Museum of Zoology, Dr. Norman Hartweg; United States National Museum, Dr. D. M. Cochran. Dr. E. H. Taylor, University of Kansas, and Mr. Robert Roecker, Cornell University, kindly lent me specimens from their private collections. Dr. W. H. Stickel, United States Fish and Wildlife Service, graciously permitted me to use his field notes, made on Mindoro. Finally, I am grateful to my wife, Mary Lee Inger, for typing parts of the manuscript and for her patient editorial assistance. GEOGRAPHIC NOTES The physical geography of the Philippine Islands has frequently been described. Although this paper has no new information to offer, a brief outline is presented here for use in connection with the discussions of species ranges and ecological notes. The Philippine archipelago (fig. 28), situated between 5° and 22° N. Lat. and 117° and 127° E. Long., includes more than 7,000 Fig. 28. The Philippine Islands. Topography adapted from King and McKee (1949). 187 188 FIELDIANA: ZOOLOGY, VOLUME 33 islands, of which only slightly more than 450 exceed 2.5 square kilometers in area. The two largest, Luzon and Mindanao, have areas of 105,708 and 95,587 square kilometers, respectively. The latter is approximately equal in area to Hungary or to the state of Indiana. The central islands of Panay, Negros, Cebu, Bohol, Si- quijor, Leyte, and Samar are often referred to as the Visaya Islands. The small islands between Borneo and Mindanao are grouped under the term Sulu Islands or Sulu Archipelago. Generally, the islands are mountainous. Luzon, Mindoro, Pala- wan, Mindanao, Negros, Panay, and Sibuyan have elevations greater than 1,500 meters. Broad plains occur in central Luzon, western Negros, and northeastern Leyte. In the eastern part of the archi- pelago, the mountain ranges have a northwest-southeast trend, whereas in the west the trend is northeast-southwest. The east border of the archipelago is formed by the Mindanao Trench, which attains depths in excess of 10,000 meters. Most of the Celebes Sea, on the southern border, is below the 4,000 meter isobath. The South China Sea on the west is a shallow basin for the most part, although it, too, reaches the 4,000 meter isobath. The Sulu Sea, surrounded by Borneo and the Philippines, contains large areas that are over 4,000 meters deep. Of the waters com- pletely enclosed by the Philippine Islands only a small area, in the Mindanao Sea north of Mindanao, is more than 2,000 meters deep. Large areas of the enclosed waters are less than 200 meters deep. The flanks of the Sulu Sea are formed by two submarine ridges, running from Borneo northward to include Palawan and the Cala- mian Islands and from Borneo northeastward to the Sulu Archi- pelago and western Mindanao. Only the second of these has small strips lying below 100 meters. A third submarine ridge, which is forked, passes southward from eastern Mindanao. Both branches run toward Celebes, one indicated by the Sangihe and Sarangani Islands and the other by the Talaud Islands. Except where these islets emerge, this forked ridge does not rise above the 200 meter isobath. Major topographic features are illustrated in figures 28 and 29. NOTES ON THE ENVIRONMENT OF THE PHILIPPINE AMPHIBIA A discussion of the Philippine Islands as an environment is worthy of a separate volume. This section is offered not as a sub- stitute for such a discussion but merely as a compendium of miscel- Fig. 29. The submarine topography of the Philippine Islands. 189 190 FIELDIANA: ZOOLOGY, VOLUME 33 laneous information that may serve as a background against which the ecological notes of the individual species can be considered. Climate.—The climate of the Philippine archipelago is tropical— temperature and rainfall are generally high. The notes that follow are taken from Coronas (in Merrill, 1926), Maso (1914), and Selga (1935). Average annual temperature for fifty stations situated near sea level from the Batan Islands north of Luzon to Palawan, southern Mindanao, and the Sulu Islands ranges only from 25.8° to 27.9° C. The range of mean monthly temperatures is slight but varies geographically from south to north. The range is 3° C. at Jolo in the Sulu Islands and 8° C. at Aparri on the north coast of Luzon. Not many observations are available for high altitudes. At 1,500 meters on Mount Mirador, Mountain Province, Luzon, mean tem- perature over a sixteen-year period was 17.9° C. In the mountains of northern Luzon, light frosts and snows are not uncommon during December and January. Both the amount and the seasonal distribution of rainfall vary geographically. The mean annual rainfall for 350 stations ranges from 963 mm. at Padada, Davao Province, Mindanao, to 4,436 mm. at the City of Baguio, Luzon; over the entire archipelago the mean is in excess of 2,000 mm. With regard to the seasonal dis- tribution of rainfall, the Philippines may be divided into three climatic zones.