Morphology and Systematics of the Solomon Island Ranid Frogs
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Morphology and Systematics of the Solomon Island Ranid Frogs Rachel M. Norris Department of Environmental Biology The University of Adelaide A thesis submitted for the degree of Doctor of Philosophy, at the University of Adelaide December, 2002 i Table of Contents Abstract iv Declaration vi Acknowledgements vii Publications resulting from this thesis viii Chapter 1. Introduction 1 Chapter 2. Historical Account 6 2.1. Taxonomy of the Solomon Island ranids: Species accounts 6 2.2. Taxonomy of the Solomon Island ranids: Subfamily accounts 22 2.3. Mode of Life History: a uniting feature? 29 2.4. Zoogeography of the Solomon Islands and surrounding islands 31 Chapter 3. Morphometrics 38 3.1. Introduction 38 3.2. Methods 39 3.2.1. How many PCs? 41 3.3. Results 42 3.3.1. Analysis of Separate Sexes 42 3.3.2. Analysis of Sexes Combined 50 3.3.3. Further Analysis: Discriminant Function Analysis 65 3.4. Discussion 76 Chapter 4. Osteology of Solomon Island Ranids 79 4.1. Introduction 79 4.2. Methods 79 4.2.1. Material Examined 80 4.3. Osteological Descriptions 81 4.3.1. Batrachylodes Boulenger, 1887 81 4.3.1.1. Batrachylodes elegans Brown and Parker, 1970 81 4.3.1.2. Batrachylodes mediodiscus Brown and Parker, 1970 83 4.3.1.3. Batrachylodes trossulus Brown and Myers, 1949 86 4.3.1.4. Batrachylodes vertebralis Boulenger, 1887 92 4.3.1.5. Batrachylodes wolfi (Sternfeld, 1918) 97 4.3.2. Ceratobatrachus Boulenger, 1884 102 4.3.2.1. Ceratobatrachus guentheri Boulenger, 1884 102 4.3.3. Discodeles Boulenger, 1918 109 4.3.3.1. Discodeles bufoniformis (Boulenger, 1884) 109 4.3.3.2. Discodeles guppyi (Boulenger, 1884) 115 4.3.4. Palmatorappia Ahl, 1927 120 ii 4.3.4.1. Palmatorappia solomonis (Sternfeld, 1920) 120 4.3.5. Platymantis Günther, 1859 "1858" 126 4.3.5.1. Platymantis guppyi (Boulenger, 1884) 126 4.3.5.2. Platymantis myersi Brown, 1949 132 4.3.5.3. Platymantis neckeri (Brown and Myers, 1949) 138 4.3.5.4. Platymantis parkeri (Brown, 1965) 143 4.3.5.5. Platymantis solomonis (Boulenger, 1884) 149 4.3.5.6. Platymantis weberi Schmidt, 1932 155 4.3.6. Rana Linnaeus, 1758 160 4.3.6.1. Rana kreffti Boulenger, 1882 160 Chapter 5. Karyology of the Solomon Island Ranids 167 5.1. Introduction 167 5.2. Methods 167 5.2.1. Material examined 167 5.2.2. Preparation of Chromosome spreads 168 5.2.3. Giemsa Banding (G-banding) 168 5.2.3.1. Procedure 169 5.2.4. Constitutive Heterochromatin Banding (C-banding) 169 5.2.4.1. Procedure 170 5.2.5. Silver Staining - Staining for active nucleolus organiser regions 170 5.2.6. Photomicroscopy 170 5.3. Results 171 5.3.1. Solomon Island species 171 5.3.2. Comparison Species from literature 178 5.4. Discussion 181 Chapter 6.Phylogenetic Analysis 184 6.1. Introduction 184 6.2. Methods 185 6.2.1. Character Selection 191 6.2.2. Outgroup selection 192 6.2.3. Assumptions for phylogeny reconstruction 193 6.2.3.1. Character weighting 193 6.2.3.2. Missing data 193 6.2.3.3. Character ordering 194 6.2.4. Support and Confidence 194 6.3. Results 195 6.3.1. Analysis 1 195 6.4. Character Reassessment 217 iii 6.4.1. Analysis 2 217 6.4.2. Analysis 3 221 6.4.3. Analysis 4 224 6.5. Discussion 225 References 230 Appendix 1. Material Examined 242 Appendix 2. 273 Discriminant Function Analysis 273 Boxplots genera females 277 Boxplots genera males 280 Boxplots species females 283 Boxplots species males 300 Appendix 3. Character Descriptions 315 iv Abstract The ranid frogs of the Solomon Islands have been known in the taxonomic literature for over 100 years. The Solomon Islands and surrounding islands contain a unique array of direct-developing ranids, most of which are endemic to the island masses on which they live. However, their phylogenetic relationships to each other and to other ranids in the southwest Pacific region have not been defined. Their assumed relationships are based on a restricted sample of osteological characters and the assumption of direct development, inferred from egg size and number. This study validates the Solomon Island taxa (using morphometrics) and explores the biology of the Solomon Island ranids, with detailed osteological descriptions, external morphology and karyology. Using characters from these data sets a cladistic analysis using parsimony reconstructed a phylogeny of these frogs. Morphometric analyses were undertaken on two levels, firstly using principal components analysis (PCA) to assess sexual dimorphism, and secondly using discriminant function analysis (DFA) to test the identity of the taxa. Sexual dimorphism was not recognised in morphometric characters and so sexes were pooled for the DFA. For Batrachylodes 93.08% of individuals were successfully classified to their actual groups, Discodeles 89.77% and for Platymantis 84.55%. Osteological descriptions of Batrachylodes elegans, B. mediodiscus, B. trossulus, B. vertebralis, B. wolfi, Ceratobatrachus guentheri, Discodeles bufoniformis, D. guppyi, Palmatorappia solomonis, Platymantis guppyi, P. myersi, P. neckeri, P. parkeri, P. solomonis, P. weberi and Rana kreffti are provided. Karyotypes of eight species of ranid frogs from the Solomon Islands were compared and contrasted with the 2n = 26, FN = 52 karyotype of Rana, the typical karyotype of the subfamily Raninae. This karyotype was found in the Solomon Island species of Rana, R. kreffti. Ceratobatrachus guentheri, had an increased 2n of 30, a lower FN of 38, and altered relative lengths and centromere positions of pairs 1-5. These changes could have resulted from centric fissions and pericentric rearrangements which produced an increase in the number of telocentric chromosomes. The remaining seven species (Batrachylodes vertebralis, Discodeles bufoniformis, D. guppyi, Platymantis myersi, P. neckeri, P. solomonis and P. weberi) had reduced diploid numbers and FN. The means by which reduction in 2n and FN has occurred in these species is unknown, but may either involve centric fissions to produce telocentrics, followed by translocation onto other v chromosomes, or a process involving pericentric rearrangements to produce telocentric chromosomes followed by fusions of these products. With the exception of Rana, the level of chromosome rearrangements in these frogs that are endemic to the Solomon Islands is high compared with that observed in the continental lineages of this subfamily. Phylogenetic analysis using maximum parsimony found three equally parsimonious trees. Subsequent character reanalysis (successive weighting) produced one parsimonious tree. The phylogenies indicate multiple invasion events into the Solomon Islands by these ranid frogs and despite the high level of endemism, monophyly is not supported. vi Declaration This work contains no material which has been accepted for the award of any other degree or diploma in any university or tertiary institution and, to the best of my knowledge and belief, contains no material previously published or written by another person, except where due reference has been made in the text. I give consent to this copy of my thesis, when deposited in the University Library, being made available for loan and photocopying. vii ACKNOWLEDGEMENTS I would like to thank the following people and institutions who have waited patiently for this thesis. ■ Associate Professor Michael Tyler, for supervising the thesis, for your advice and support and willingness to read it and help. ■ Dr Margaret Davies, for tirelessly pursuing me to keep on track. Without your advice and support and editing skills I doubt I could have finished it. ■ The Department of Environmental Biology (formerly Zoology) for their patience. I'm sorry Bill that you didn’t get to read it. ■ Professor Maciej Henneberg and the Department of Anatomical Sciences, for support and study leave. ■ Professor Arnold Kluge, thank you so much for your advice and help throughout this thesis. ■ Dr Tom Burton, for the visit all those years ago, only to find out that in Solomon Island ranids, big frogs have big muscles and little frogs have little muscles. ■ Dr Michael Mahony, University of Newcastle, for support and advice on the chromosomes. ■ Dr Steve Donnellan, South Australian Museum, for collecting frogs and trying to get some molecular work up and running, alas just not my thing. ■ Dr Mark Hutchinson, South Australian Museum, for discussions on cladistics and reading a draft of chapter 6. ■ Mr Jens Vindum, Dr Alan Leviton, Department of Herpetology, California Academy of Sciences; Mr José Rosado, Museum of Comparative Zoology, Harvard; Prof. Arnold Kluge, Department of Zoology, University of Michigan; Dr Darrel Frost, Department of Herpetology, American Museum of Natural History; Mr Alan Resetar, Dr Harold Voris, Field Museum of Natural History, Chicago; Mr Ross Sadlier, Dr Alan Greer, Division of Herpetology, Australian Museum, Sydney; Ms Adrienne Edwards, Dr Mark Hutchinson, Division of Herpetology, South Australian Museum, Adelaide, for allowing me to visit their departments and the loan of material. ■ The Royal Society of South Australia, The American Museum of Natural History, The Field Museum of Chicago, The DR Stranks Travelling Fellowship and the University of Adelaide Overseas Travelling Scholarship for various funding to allow me to pursue all aspects of this thesis and the support of The University of Adelaide Postgraduate Scholarship. ■ My family. ■ My friends especially Carmel, Anna and Genevieve. viii Publications Resulting from this Thesis Mahony, M.J., Norris, R.M. and Donnellan, S.C. (1996) Karyotypes of Southwest Pacific Ranid Frogs (Anura: Ranidae). Australian Journal of Zoology, 44, 119- 128. Norris, R.M. (1999) Testing multiple species hypothesis on frogs. Perspectives in Biology, 4(1):51-64 Chapter 1. Introduction The Solomon Islands have been regarded as an amphibian outpost (Boulenger, 1886a; Brown, 1952). Boulenger (1886a:35) considered the Islands to be “on the limits of two great zoological districts..