A synopsis of Ptisana Murdock ferns (Marattiaceae) in New Caledonia based on sequence data and morphology with the recognition of a new vulnerable species, P. soluta (Compton) Murdock & Perrie, comb. nov., stat. nov.

While New Caledonia is known as a centre of plant endemism, its fern flora has been under-studied. Recent collections of Ptisana Murdock, a genus often poorly represented in herbaria due to their large size, enabled new molecular phylogenetic investigation and a reassessment of previously proposed taxonomies based on morphology. Sequence data from the endangered (EN) dwarf species P. rolandiprincipis (Rosenst.) Christenh. are obtained for the first time and confirm that it is genetically distinct and warrants recognition at the species level. Previous studies suggested that the widespread South Pacific species P. salicina (Sm.) Murdock was present in New Caledonia. However, revised analyses indicate that the New Caledonian plants are an endemic species, recognised here for the first time at the species rank as Ptisana soluta (Compton) Murdock & Perrie, comb. nov., stat. nov., with a vulnerable (VU) conservation ranking. The most common species, the New Caledonian endemic P. attenuata (Labill.) Murdock, is shown to be genetically variable, and warrants further systematic and phylogeographic investigation.