A new species of Asplenium section Thamnopteris (Aspleniaceae) from Indonesia

A new species, Asplenium riswanii (sect. Thamnopteris), is described from Central Java and West Papua, Indonesia. It is distinct from any known species by having thick and rigid fronds, abaxially keeled midribs, broadly lanceolate scales, and distantly spaced sori. Morphologically, A. riswanii is not similar to any species from Malesia but somewhat close to A. antrophyoides from mainland Southeast Asia. Molecular data reveal it has an isolated position in the phylogeny. The micromorphology of spores and leaf epidermis of A. riswanii is also documented and a key to the species of Asplenium sect. Thamnopteris from Malesia is given.