Author Identifiers

Giulia Perina
ORCID: 000-0002-0349-3803

Date of Award

2019

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

School of Science

First Advisor

Associate Professor Annette Koenders

Second Advisor

Professor Pierre Horwitz

Field of Research Code

01, 0109, 010905

Abstract

Research on subterranean fauna on all continents has highlighted often high levels of endemism, for both troglobionts (terrestrial subterranean organisms) and stygobionts (organisms living in groundwater). In Australia, particularly in the arid zones of Western Australia, a rich hypogean assemblage has been discovered in the past few decades, largely due to surveys required as part of environmental impact assessments for, and imposed conditions on, mining operations. Bathynellidae (Crustacea) are part of the stygofaunal community, but to-date they are poorly understood, mainly because their conservative morphology, small size and delicate exoskeleton make their dissection, observation and study very difficult. Additionally, the incomplete description of the type genus and species of the family (Bathynella natans) have led to misidentifications and taxonomic/systematic uncertainties. Prior to this contribution, only one species of Bathynellidae had been described from Australia, and knowledge on their morphology, species/genera and distributional boundaries, inter- intraspecific variability, and origins were very limited.

The overall aim of this research is to investigate diversity, patterns of distribution, and biogeographical history of Bathynellidae in Australia, focussing on the arid zones of Western Australia (particularly on the Pilbara region).The abundance of material already collected by different companies allowed a thorough morphological and molecular examination of many specimens. The study of multiple taxa occurring in different aquifers of the same and different catchments is carried out to explore intra-interspecific variability, species and distributional boundaries, and evolutionary histories. A molecular phylogeny including representative taxa from different continents is also built to put the Australian fauna into a worldwide context.

Four new species and genera (Pilbaranella ethelensis, Fortescuenella serenitatis, Anguillanella callawaensis, and Muccanella cundalinensis) have been described, clarifying morphological and molecular intra- and interspecific boundaries. These represent the first four species described for Western Australia. One new subfamily, nine new genera, and 23 new species are recognised through molecular species delineation and preliminary morphological analysis. All species and most genera studied appear restricted to single aquifer systems in particular areas of a catchment. The molecular phylogeny of the Australian Bathynellidae indicates a complex history. The molecular clock analysis suggests that aridification processes only partly influenced the diversification, while most of their diversity predate the establishment of the drought climate. The results indicate very old origins dated back to the end of Devonian-early Carboniferous, and a substantial increase in the rate of diversification during the Triassic-Jurassic period, which could represent multiple freshwater invasions, facilitated perhaps by sea level fluctuations. A consequent dispersion thanks to a much wetter climate may explain the presence of Bathynellidae in areas of the country that have not been influenced by marine transgressions since the Proterozoic. The molecular phylogeny including genera and lineages from other countries indicates that the Australian Bathynellidae form a monophyletic clade comprising different subfamilies distinct from the ones described from other continents. This better understanding will help to predict the potential diversity of this group in unstudied areas, and enable improved advice to government regulators where protection of subterranean environments and their aquifers is a priority

Access Note

Chapters II, III and IV are not available in this online version of the thesis.

Available for download on Monday, May 24, 2021

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Biology Commons

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