Eriolaena bacgiangensis (Malvaceae), a new species from Vietnam

The new species Eriolaena bacgiangensis from Vietnam is described and illustrated. The identified key was constructed to indicate the differences amongst three allied species of Eriolaena. E. bacgiangensis was compared with similar species, E. candollei and E. wallichii.

E. bacgiangensis differs from E. candollei by the length of pedicel (1.4–2.3 cm long vs. 3.0–4.0 cm in E. candollei); presence of epicalyx after flowers at anthesis in E. bacgiangensis (vs. absence of epicalyx after flowers at anthesis in E. candollei); densely fringed epicalyx in E. bacgiangensis (vs. sparsely fringed epicalyx in E. candollei); style significantly exceeds staminal tube length in E. bacgiangensis, while the style is slightly longer than the staminal tube in E. candollei; the fruit apex round in E. bacgiangensis (vs. pointed and beaked in E. candollei).

The linear epicalyx lobes are a key diagnostic trait for distinguishing E. bacgiangensis from E. wallichii (linear vs. ovate in E. wallichii). In addition, the other different characteristics of the two species are: leaf blade (not thickly papery in E. bacgiangensis vs. thickly papery in E. wallichii); length of inflorescences (13.0–18.0 cm in E. bacgiangensis vs. ≤ 6.0 cm in E. wallichii); shape of flower bud (lanceolate in E. bacgiangensis vs. globular in E. wallichii); fruit apex (round in E. bacgiangensis vs. apex shortly beaked in E. wallichii).