Quercusmangdenensis , a new species of Quercus (Fagaceae) from Kon Tum Province, Vietnam.

Quercusmangdenensis Binh & Ngoc, sp. nov. (Fagaceae) is newly described from Mang Den Town in the central highland of Vietnam. The new species is characterized by lanceolate to oblong-lanceolate leaves with entire margin, 1-5-fruited infructescence, larger fruit size 6-10.5 cm long, broadly bowl-shaped cupules enclosing 1/5 of the nut, bracts of cupule entire and arranged in 5-7 rings, and cylindrical-ellipsoid and basally flat nuts 4.5-7.5 cm long. Quercusmangdenensis is morphologically similar to Q.bidoupensis Binh & Ngoc and Q.kontumensis A.Camus in having similar leaf shape, cuneate leaf base, and bracts arrangement in cupules. However, it differs from Q.bidoupensis and Q.kontumensis by cupules broadly bowl-shaped, much larger fruits, cylindrical-ellipsoid nut shape, and cupule enclosing 1/5 of the nuts. A description, photographs, and preliminary species conservation status of the new species are also provided.