A new combination is proposed for Phlegmariurus (Herter) Holub (Lycopodiaceae): P. obovalifolius (Bonap.) V.T. Tran & N.V. Duy, comb. nov., and a new species of Phlegmariurus, P. lancifolius V.T. Tran & N.V. Duy, sp. nov., from southern Vietnam, is described and illustrated. It is distinguished from the closely related P. obovalifolius (Bonap.) V.T. Tran & N.V. Duy, comb. nov., by its leaves lanceolate, apex acuminate-acute, 1.1-1.5 × 0.4-0.6 cm, sporophyll cuneiform or broadly ovate, c. 2 × 2 mm, apex apiculate with acuminate tip, c. 2 mm, sporangia reniform.
Lycopodiaceae, Vietnam, new combination, new species.