A cytotaxonomic survey of the Pteridophyta of Australia

Abstract

A cytotaxonomic survey of the ferns and fern allies of Australia (including Lord Howe Island) is presented. Five-hundred-and-twenty-six chromosome counts of 268 Australian species, subspecies, varieties, variants and hybrids are recorded, only a small number having been previously investigated by other botanists on Australian material. Diploids represent c. 62% of the counts on species and c. 38% on polyploids, the latter ranging principally from triploids to a single decaploid and dodecaploid (but no heptaploids). More than one ploidy level has been reported in 19 taxa (almost 8% of taxa). Counts of 10x for Asplenium aethiopicum and 12x for A. flabellifolium are the highest definite ploidy levels for the Australian pteridophyte flora. Chromosome counts for 29 families and 89 genera are cited. Only diploids were reported for Osmundaceae and Cyatheaceae, but only polyploids for the Psilotaceae, Vittariaceae and Ophioglossaceae. An analysis is given of the levels of ploidy in 248 taxa, excluding the Lycopodiaceae and Hymenophyllaceae. The percentages of diploids and polyploids in Australian species are compared with those of nearby countries. Many species reported on here have never been cytologically investigated before, while others have not been studied previously on Australian material. The following genera have been examined cytologically for the first time: Coveniella Tindale, n = 41; Paraceterach (F.Muell.) Copel., n = 29; 'Oenotrichia Copel.', 2n = 82 (2x); Revwattsia (Watts) D.L.Jones, 2n = c. 328 (8x); and Pteridoblechnum Hennipman (2n = 54). The phylogeny of the genera is discussed in the light of these findings. Certain families such as the Adiantaceae, Cyatheaceae, Hymenophyllaceae, Lindsaeaceae and Marsileaceae were given special attention by collecting as much living material as possible. A number of species-complexes has been found and further chromosome counts added to intercontinental species complexes. The Döpp-Manton and Braithwaite forms of reproductive apomixis have been reported amongst some genera. Endemism, hybridity and apogamy amongst Australian pteridophytes are discussed, as well as homosporous and heterosporous species. The new combination Phymatosorus membranifolius (R.Br.) Tindale is made.