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New eucalypt taxa for the island of Tasmania

ecordata gay mckinnon

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)

­gay mckinnon, brad potts, gintaras kantvilas

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.

enebulusa - sepentime ridge

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)

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.