Polystichum kungianum, sp nov (sect. Mastigopteris, Dryopteridaceae) from Chongqing, China

A new fern species, Polystichum kungianum (sect. Mastigopteris, Dryopteridaceae), is described from Chongqing, China. The new species, occurring on limestone walls near a small karst cave, is the fourth species known so far in the section Mastigopteris. It is morphologically most similar to P. erosum, but its pinnae are deltate-lanceolate, and those below the middle of lamina are profoundly pinnatifid. It has an inconspicuous terminal bulbil at the apex of the rachis which never elongates, and its basal pair of pinnae is never reflexed. These differences are obviously distinct from P. erosum and make it clear that it could not merely be a variant population within that species, but must be a distinct species. Morphological and geographical features of the accepted species in sect. Mastigopteris are discussed, and a key to all four species is given.