Amphipoda: Talitridae
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Keratroides vulgaris (Friend) The taxonomy, zoogeography and aspects of the ecology of the terrestrial amphipods (Amphipoda:Talitridae) of Tasmania by James Anthony Friend, B.Sc.(Hons) submitted in fulfilment of the requirements for the degree of Doctor of Philosophy UNIVERSITY OF TASMANIA HOBART December, 1980. Except as stated herein, this dissertation contains no material which has been accepted for the award of any other degree or diploma. To the best of my knowledge and belief, it contains no copy or paraphrase of material previously published or written by another person, except where due reference is made in the text. ao\ CONTENTS Page Summary Acknowledgements vii Chapter 1 : Introduction 1 Part I : Taxonomy and Zoogeography Chapter 2 :: Approach to Systematics 11 Chapter 3 : Taxonomy Section 3.2 : Introduction 27 Section 3.2 : Methods 27 Section 3.3 : Systematics 29 Section 3.4 : Discussion 136 Chapter 4 : Distribution and Zoogeography Section 4.1 : Introduction 139 Section 4.2 : Environments, present and past 146 Section 4.3 : Distribution of Tasmanian land amphipods 155 Section 4.4 : Discussion 172 Part II : Ecological Studies Foreword 183 Chapter 5 : Environment Section 5.1 : Location and Access 184 Section 5.2 : Climate 184 Section 5.3 : Temperature measurement 185 Section 5.4 : Relative humidity measurement 188 Section 5.5 : Botanical description 189 Section 5.6 : Phenology 190 Section 5.7 : Soil and litter characteristics 191 Section 5.8 : Fauna 193 iv Page Chapter 6 : Litter Fall and Decomposition Section 6.1 : Introduction 200 Section 6.2 : Methods 201 Section 6.3 : Results 203 Section 6.4 : Discussion 208 Chapter 7 : Niche Separation Section 7.1 : Introduction 213 Section 7.2 : Methods and Results 215 Section 7.3 : Discussion 235 Chapter 8 : Population Dynamics and Reproduction Section 8.1 : Introduction 249 Section 8.2 : Methods 251 Section 8.3 : Results 255 Section 8.4 : Discussion 265 References 272 Appendices 301 Appendix I 302 Appendix II 335 Appendix III following 346 SUMMARY Amphipods of the family Talitridae form an important part of the cryptozoa of Tasmanian forests. This terrestrial amphipod fauna comprises fifteen species, and twelve of these are described as new. The currently widely-used grouping of land amphipods into the genera Orchestia and Talitrus is considered unsatisfactory and consequently new genera are proposed for the Tasmanian species. A key for the identification of these species is provided. The detailed distribution of each of these species is presented and discussed with respect to the environments present in Tasmania and their history. Four of the seven Tasmanian genera, but only one of the fifteen species, are found on the mainland of Australia. Examination of geological and paleo- climatic data leads to the suggestion that this situation is due to the par- ticular conditions which prevailed on former land connections, during Tertiary and late Quaternary times. The world distribution of terrestrial amphipods is examined in the light of local knowledge. A Gondwanaland radiation of the Talitroidea is suggested, and the proposal that supralittoral talitrids were not present in the Laurasian continents until the late Tertiary is advanced. Ecological studies of land amphipods in Tasmania were focussed on the areas of niche partition and the dynamics of populations and their environment. All investigations were carried out at a site in wet sclerophyll forest in eastern Tasmania. Two species, sympatric at the study site, were found to display a number of ecological differences which may explain their coexistence. Keratroides vulgaris appears to be a litter-dwelling, actively-colonizing species, while K. angulosus possesses morphological and behavioural attributes which apparently fit it better for its demonstrated existence at a lower level in the litter/ soil profile. Litter fall and decomposition was studied at the study site over 18 months. Annual litter fall was 9390 kg/ha, which is high compared with results from vi studies in other Australian forests. While litter fell throughout the year, there was a distinct summer peak. Estimates of the rate of disappearance of litter indicated a low turnover time, approaching those found in forests in much warmer climates. The concentrations of several important nutrients in components of the newly-fallen litter and the forest floor at the study site were measured. Levels of most of these nutrients, especially phosphorus, proved higher than those found in other Australian forests. The numbers and structures of populations of K. vulgaris and K. angulosus were also monitored for 18 months. High densities of both species were 2 2 maintained throughout this time, reaching maxima of 24311m and 6185/m respectively, in December 1977. Ovigerous females of both species were found almost exclusively between September and May, and photoperiod control of the winter resting stage is suggested. Both species displayed two-year life cycles and many individuals apparently bred during consecutive summers. Comparison of patterns of reproduction found in this and other populations of terrestrial talitrids reveals a wide diversity of strategies within this group. vii ACKNOWLEDGEMENTS There are many people to whom I would like to express my sincere gratitude at this point. These include: My supervisor, Dr. Alastair Richardson, for his continual interest, encouragement and friendship, My colleagues and friends at the Zoology Department for their companion- ship, cooperation and much helpful discussion, Dr. Ed Bousfield, Natural History Museum, Ottawa, for his interest and for advice on drawing techniques, Dr. Jim Lowry, Australian Museum, Sydney, for help and encouragement over several years, The Director and Trustees of the Australian Museum, for the opportunity - to work at the Museum from March until August 1980, providing an experience which stimulated a number of ideas expressed below, The many people who collected amphipod material used in this study, and whose names appear on p.334, Dr. Roy Swain, for reading the drafts of several chapters and making many helpful suggestions, Lyn Wilson, for accurately typing this dissertation, and carring out gross alterations without a murmur of complaint, Jenny Smith, for friendship and assistance, and particularly for compiling Appendix I, My parents, Dr. Alan and Mrs. Robin Friend, for much generous support and for provision of facilities for the final period of writing-up, and especially Jo Friend, without whose moral and financial support I would not have finished this study, and who laboured long to draw most of the graphs in the following pages. I am also grateful for support from a Commonwealth Postgraduate Research Grant. CHAPTER ONE INTRODUCTION Terrestrial amphipods are an important element of the leaf litter and soil fauna of the wetter forests of eastern Australia, both in terms of numbers (Sayce, 1909; Campbell and Gray, 1942; Clark, 1954; Sandell, 1977; Friend and Richardson, 1977) and in terms of their contribution to litter decomposition (Clark, 1954; Friend, 1975). The group is widely distributed in tropical and southern hemisphere areas of the world (Hurley, 1968). Discounting known introductions, there are published records from Australia, New Guinea, New Zealand and its sub- antarctic islands, South Africa, Madagascar, India, Ceylon, Burma, Singapore, Indonesia, the Philippines, Japan, most major Pacific and Indian Ocean island groups, the Azores, Madeira, Canary Is., and Annobon I. Unpublished records from Jamaica, Haiti and Panama are cited by Hurley (1968), while an endemic species has also been found in Mexico (E.L. Bousfield, pers. comm.). The known distribution of this fauna is shown in Figure 4. 1. The importance of this cryptozoan group is certainly belied by the small amount of ecological literature devoted to it (see below). The lack of attention has been attributed to the absence of native land amphipods from much of the northern hemisphere, where most ecological research has been car- ried out (Friend and Richardson, 1977). While perhaps explaining the state of terrestrial amphipod ecology, this world distribution also presents an interesting zoogeographical problem, to which a comprehensive answer has not been provided. It is widely agreed that fully land-dwelling amphipods, which belong to the family Talitridae, arose from species similar to those commonly found on seashores (Bulycheva, 1957; Hurley, 1959, 1968; Bousfield-, 1968; Wildish, 1979). Representatives of this supralittoral group, however, are present on seashores on all continents and on islands of both hemispheres, to about 600 latitude, north and south (Bulycheva, 1957). The problem, then, is to explain why terrestrial amphipods are so poorly represented in 2 the northern hemisphere, where supralittoral species are quite common. In the course of a zoological survey by the present author and fellow honours students in 1974, it became obvious that there is a relatively rich and largely undescribed terrestrial amphipod fauna in Tasmania. It was also discovered that it is usual to find several species together in the forest floor. These findings invited research in two different, but not unrelated, directions. Description of the land amphipod fauna was a definite priority; it is largely the lack of knowledge of cryptozoan groups which has discouraged ecological work on the Australian forest floor fauna (see below). The unsettled state of terrestrial talitrid taxonomy (Chapter 2) quickly became evident, as did the poor knowledge