Eriolaena bacgiangensis (Malvaceae), a new species from Vietnam

The new species <i>Eriolaenabacgiangensis</i> from Vietnam is described and illustrated. The identified key was constructed to indicate the differences amongst three allied species of <i>Eriolaena</i>. <i>E.bacgiangensis</i> was compared with similar species, <i>E.candollei</i> and <i>E.wallichii</i>. <i>E.bacgiangensis</i> differs from <i>E.candollei</i> by the length of pedicel (1.4-2.3 cm long vs. 3.0-4.0 cm in <i>E.candollei</i>); presence of epicalyx after flowers at anthesis in <i>E.bacgiangensis</i> (vs. absence of epicalyx after flowers at anthesis in <i>E.candollei</i>); densely fringed epicalyx in <i>E.bacgiangensis</i> (vs. sparsely fringed epicalyx in <i>E.candollei</i>); style significantly exceeds staminal tube length in <i>E.bacgiangensis</i>, while the style is slightly longer than the staminal tube in <i>E.candollei</i>; the fruit apex round in <i>E.bacgiangensis</i> (vs. pointed and beaked in <i>E.candollei</i>). The linear epicalyx lobes are a key diagnostic trait for distinguishing <i>E.bacgiangensis</i> from <i>E.wallichii</i> (linear vs. ovate in <i>E.wallichii</i>). In addition, the other different characteristics of the two species are: leaf blade (not thickly papery in <i>E.bacgiangensis</i> vs. thickly papery in <i>E.wallichii</i>); length of inflorescences (13.0-18.0 cm in <i>E.bacgiangensis</i> vs. ≤ 6.0 cm in <i>E.wallichii</i>); shape of flower bud (lanceolate in <i>E.bacgiangensis</i> vs. globular in <i>E.wallichii</i>); fruit apex (round in <i>E.bacgiangensis</i> vs. apex shortly beaked in <i>E.wallichii</i>).