Quercus zhekunii, a new sclerophyllous oak from Guangxi, southwest China

Asian (sub)tropical karst regions harbor high endemism and species
diversity of sclerophyllous oaks. In this study, Quercus zhekunii, a new
species from Guangxi, China, is described and illustrated. Phylogenomic
reconstruction using RAD-seq placed this new species within the “Tropical
Clade” of Quercus sect. Ilex. The dense fused fasciculate and uniserate
trichomes on the leaf abaxial surface of Q. zhekunii resemble those of Q.
kingiana. However, its distinctively concave primary and lateral veins on
the leaf adaxial surface, along with the prominent backward-recurved leaf
blade and leaf margin, make it morphologically distinct from any known
species in Q. sect. Ilex. The conservation status of Q. zhekunii is
assessed as Endangered (EN). A new identification key to the species in
the “Tropical Clade” is provided. In addition, character evolution and
phylogeography of the “Tropical Clade” of Q. sect. Ilex is briefly
discussed based on the new phylogenetic and morpho-anatomical data.