Dryopteris pycnolepis, a new fern species from northern Vietnam, with miscellaneous notes on Dryopteris sect. Splendentes (Dryopteridaceae)

A new woodfern species, <i>Dryopteris pycnolepis</i>, is described from northern Vietnam. The new species differs mainly in having broadly lanceolate scales (versus ovate-lanceolate) on the stipe and rachis, lateral pinnae with the basal acroscopic pinnules longer than their immediately adjacent pinnules (versus subequal), and fibrillose scales present on both surfaces of pinnules (versus glabrous). Phylogenetic analyses of plastome sequences support both the distinctness of <i>D. pycnolepis</i> as a species and its close affinity to <i>D. sikkimensis</i>. Morphological comparisons and phylogenetic analyses confirm that these two species, together with <i>D. rubrobrunnea</i> and <i>D. splendens</i>, form a small natural group (i.e., sect. Splendentes) within the <i>Dryopteris</i> clade of this genus. It appears to be a replacement species of the Sino-Himalayan <i>D. sikkimensis</i> in northern Vietnam. Section Splendentes is shown to be geographically restricted to the Sino-Himalaya region and northern Vietnam, excluding eastern Asian species previously included in this section. The discrepancy between phylogenetically and morphologically inferred interspecific relationships within sect. Splendentes is highlighted and briefly discussed. The correct authorship of the name <i>D. splendens</i> is noted to be "(Bedd.) Kuntze."