Cyathea lamoureuxii (Cyatheaceae): a remarkable new species from the Papuan Peninsula of New Guinea

Cyathea lamoureuxii is described from recent exploratory surveys in Papua New Guinea. The new fern is unique among eastern Malesian congeners for its undivided pinnae, and is also the only member of its subgenus with manifestly pinnate leaves. The manner in which the novelty combines diagnostic features across infrageneric lines underscores the difficulties in drawing absolute separations at the subgenus and sectional levels.