Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand

Abstract

The genus Empodisma comprises two species that are ecologically important in wetland habitats. Empodisma gracillimum is restricted to south-western Australia, whereas Empodisma minus is found in Tasmania, eastern Australia and New Zealand. We sequenced three cpDNA genes for 15 individuals of Empodisma sampled from throughout the range of the species. The results support an Australian origin for Empodisma sometime during the late Oligocene to early Miocene with more recent dispersal, colonization and diversification in New Zealand. We recovered six genetically distinct maternal lineages: three Empodisma gracillimum haplotypes corresponding to the three accessions in our analysis, a wide-ranging Empodisma minus haplotype found in eastern Australia and Tasmania, an Empodisma minus haplotype found in New Zealand from Stewart Island to approximately 38° S latitude on the North Island, and a distinct haplotype restricted to the North Island of New Zealand north of 38° S latitude. The Eastern Australian and New Zealand haplotypes of Empodisma minus were supported by only one cpDNA gene, and we felt the relatively minor morphological differences and the small amount of genetic divergence did not warrant taxonomic recognition. However, we recommend that the northern New Zealand haplotype should be recognized as the new species Empodisma robustum and provide descriptions and a key to the species of Empodisma. Monophyly of Empodisma robustum is supported by all three cpDNA genes. Empodisma robustum can be distinguished from Empodisma gracillimum and Empodisma minus by its robust growth stature and distinct ecology. It is typically eliminated by fire and re-establishes by seed (seeder strategy), whereas Empodisma minus and Empodisma gracillimum regrow after fire (sprouter strategy).

Subsidence Rates of Drained Agricultural Peatlands in New Zealand and the Relationship with Time since Drainage

“…Clarkson), and cane rush ( Sporodanthus ferrugineus , delange, Heenan, et B.D. Clarkson) (Lowe, 1985; McCraw, 2002; Wagstaff and Clarkson, 2012). Maximum and mean peat depths in 1978 were about 11.5 and 4.1 m for Moanatuatua and 11.0 and 5.3 m for Rukuhia, respectively (Daveron, 1978).…”

Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

“…In northern New Zealand, bogs and fens are dominated by the vascular evergreen "wire rush," Empodisma robustum [Wagstaff and Clarkson, 2012], which is aerenchymous [Sorrell et al, 2002] and is the primary peat-forming material through its root clusters [Agnew et al, 1993]. Northern New Zealand raised bogs have developed under warm annual temperatures and summer water deficits, climatic conditions that would generally be considered unfavorable for bog formation and persistence [McGlone, 2009].…”

Phylogeography of six codistributed New Zealand cicadas and their relationship to multiple biogeographical boundaries suggest a re‐evaluation of the Taupo Line

“…The Kauri Line is named for the southern limit of the kauri, Agathis australis (Araucariaceae; Wagstaff & Clarkson, 2012). It has been suggested that continuous forest habitat was largely restricted in North Island to Northland and Auckland regions during the LGM (Fleming, 1962;Alloway et al, 2007;McGlone et al, 2010).…”

“…Map of North Island, New Zealand, showing the placement of biogeographical boundaries referenced in this study: Northland Line, Kauri Line (after Wagstaff & Clarkson, ), Cockayne's Line, East Cape zone. (a) Cicada species ( Kikihia spp.)…”