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Gay McKinnon (UTAS) checks the subspecies
affinities of a recently discovered, large population of E.
cordata at Corbetts Hill in eastern Tasmania. (Photo: Brad
Potts)
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Brad Potts (left), Gintaras Kantvilas (Director,
Tasmanian Herbarium) and Gay McKinnon (right) allocate
subspecies labels to specimens of E. cordata held at the
Tasmanian Herbarium.
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The Tasmanian peppermint population from
Serpentine Ridge near Tulla in north-western Tasmania. These
trees will be described as a new taxon, Eucalyptus
nebulosa (Gray, in press). (Photo: B. Potts)
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Brad Potts
University of Tasmania
While publications such as
EUCAFLIP describe the nodes of eucalypt diversity on the island
of Tasmania, the current species level treatments of many of our
eucalypt species does not account for (i) the often continuous
nature of the variation between species (e.g. E. globulus,
E. bicostata, E. pseudoglobulus and E.
maidenii), nor (ii) the large amount of spatially or
ecologically structured genetic diversity which can occur within
currently recognised species. The later is particularly the case
for species where continuous populations occur along marked
environmental gradients or for species that comprise small,
isolated populations. For finer-scale management of our forest
genetic resources, it is important that formal ‘labels’
be given to identifiable components of this genetic diversity,
particularly where it is spatially or ecologically explicit.
Such formal treatments can be time consuming but are important to
allow the transfer of scientific knowledge to data bases such as
the Tasmanian
Natural Values Atlas and thus to planners and managers of our
native forests.
We have now formally described two subspecies of the Tasmanian
endemic Eucalyptus cordata, which were suggested initially
nearly twenty years ago (Potts 1989). The western,
square-stemmed form of this species has now been described as
E. cordata subspecies quandrangulosa, where as
the eastern round-stemmed form remains as E. cordata
subspecies cordata (Nicolle et al. in press).
This description was undertaken in collaboration with the
well-known eucalypt taxonomist Dean Nicolle who established the
Currency Creek Arboretum in
South Australia and Dr Gay McKinnon (UTAS) who has studied the
molecular genetics of this E. cordata as part of an ARC
Discovery grant. Despite the naturally restricted and scattered
distribution of the species, E. cordata (subspecies
cordata) was first described by Jacques-Julien de
Labillardiére in 1806 from specimens he collected in 1793
while chief scientist aboard the French expedition ships
la Recherche and l’Espérance
(Potts 1988). He
collected the type specimen of E. cordata from the tiny
Penguin Island while the expedition was anchored in Adventure Bay,
off Bruny Island. Eucalyptus cordata is an RFA priority
species, but despite the restricted distribution of each
subspecies, the number and sizes of populations are large enough
that neither is likely to qualify for listing as threatened under
State or Commonwealth legislation.
Other taxonomic descriptions on the horizon for the Tasmanian
eucalypts include the publication of new peppermint taxon (E.
nebulosa) by Alan Gray (in press) of the Tasmanian Herbarium.
This taxon refers to a population that occurs on the west coast of
Tasmania at Serpentine Ridge and, if it proves to be restricted to
this locality, the vegetation community may qualify for listing as
'rare' under State legislation.
Gray, A.M. (in press) A New Species of Eucalyptus Series
Radiatae, subgenus Monocalyptus, (Myrtaceae) from
north-western Tasmania. Kanunnah
Nicolle D, Potts BM, McKinnon GE (in press) Eucalyptus
cordata subsp. quadrangulosa (Myrtaceae), a new taxon
of restricted distribution from southern Tasmania. Papers and
Proceedings of the Royal Society of Tasmania.
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