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Abstract

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 paleoclimatic
data leads to the suggestion that this situation is due to the particular
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
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
maintained throughout this time, reaching maxima of 2431/m 2 and 6185/m2
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.

Item Type:	Thesis - PhD
Authors/Creators:	Friend, James Anthony
Keywords:	Amphipoda
Copyright Holders:	The Author
Copyright Information:	Copyright 1980 the author
Additional Information:	Thesis (Ph.D.)--University of Tasmania, 1981. Includes appendix of previously published articles on Talitridae authored or co-authored by J. A. Friend. Bibliography: l. 272-300 (pt. 2)
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