Polystichum puteicola, sp. nov. (sect. Haplopolystichum, Dryopteridaceae) from a karst sinkhole in Guizhou, China based on molecular, palynological, and morphological evidence.

A new fern species, Polystichum puteicola (sect. Haplopolystichum, Dryopteridaceae), is described from a karst sinkhole in northwestern Guizhou, China. The new species is morphologically similar to P. obliquum, a species disjunctly occurring in limestone areas in Taiwan, southwestern China to the western Indo-Himalaya. Polystichum puteicola has lamina not contracted towards base (with the largest basal pinnae), petiole scales dark brown adaxially, rachis scales up to 3.6 × 0.8 mm, pinnae dark green, subcoriaceous, lustrous adaxially, and slightly repand or almost entire on margin, and microscales up to 2 × 0.5 mm. In contrast, P. obliquum has lamina with basal pinnae contracted, scales of petiole brown adaxially, scales of rachis up to 2.3 × 0.5 mm, pinnae green, chartaceous, matt adaxially, and serrulate on margin, and microscales 0.2-0.5 × 0.1-0.2 mm. Most interestingly, the two species differs in seven positions in the DNA sequences of chloroplast trnL-F intergenic spacer. Our phylogenetic analysis shows that the two species are even not closely related. Palynologically, P. puteicola has cristate sculpture with numerous spinules on its perispore. Features of the new species in geographical distribution, ecology, spore morphology, and trnL-F sequence are given. Conservation assessments are also presented following the IUCN guidelines. [ABSTRACT FROM AUTHOR]