Abstract
A new fern species, Tectariadanangensis (Tectariaceae) from Vietnam, which had long been misreported as T.crenata, is described and illustrated. The new species resembles T.poilanei, a species long neglected in the fern flora of Indochina, in the frond shape and sori arrangement, but differs by its irregularly 2-rowed sori (versus regularly 2-rowed, distantly and evenly arranged) between lateral veins of pinnae, fronds being more or less dimorphic (versus monomorphic) and basal pinnae each with a base-joined (versus free) lobe. Phylogenetic analyses of five plastid regions (atpB, ndhF + ndhF-trnN, rbcL, rps16-matK + matK and trnL-F) suggested T.danangensis has a close affinity to T.harlandii. Tectariadanangensis appears to be an intermediate species between T.harlandii and T.poilanei.