New Genus For King Fern

The King Fern or Para, long known to New Zealanders as Marattia salicina has recently (August 2008) been transferred to a New Genus Ptisana by American botanist Andrew Murdock. Murdock’s treatment, published in Taxon (57(3): 737-755, (2008)) is the conclusion of lengthy study involving multiple molecular markers backed up with a critical re-evaluation of the morphology of the Marattiaceae. Most recent classifications have recognised two genera – Angiopteris and Marattia. Murdock proposes recognition of six, Angiopteris, Christensenia (reinstated), Danaea (reinstated), Eupodium (reinstated), Marattia (recircumscribed) and a new genus Ptisana. It is in Ptisana that, along with another 19 species, Murdock places our King Fern as P. salicina (J.M.Sm.) Murdock. Morphologically Ptisana is distinguished from the other closely allied genera Eupodium and Marattia by the sporangia which lack labiate apertures, synangia that are deeply cut, valves which generally lack flaring lips, and which have a thickened beaded texture to the outer walls of the synangia. Specifically from Eupodium, Ptisana differs by having sessile synangia that are subtended by scales or uniseriate hairs, blades that lack awns, and by the plants which bear multiple fronds. The name Ptisana comes from the superficial resemblance of the synangium to pearl barley. Murdock retains a broad circumscription for Ptisana salicina including within it plants from Norfolk Island (the type locality), New Zealand, New Caledonia, Cook Islands, Austral Islands, Society Islands and the Marquesas. However, he cautions that over this wide range the species is extremely variable and that further work may recognise additional entities within it. He also notes that P. salicina is closely allied to P. smithii of Vanuatu, Fiji, Samoa and Tonga.


Reference


Murdock, A.G. 2008: A taxonomic revision of the eusporangiate fern family Marattiaceae, with description of a new genus Ptisana. Taxon 57: 737-755.



Peter J. de Lange