The fern genus Polystichum belongs to the largest fern family Dryopteridaceae and is one of the three largest fern genera. It contains about 500 species. This genus is nearly cosmopolitan, but the species are most numerous in subtropical regions, with the highest diversity clearly in Asia, especially in southern and southwestern China and adjacent regions..

In 2009, when Prof.ZHANG Li-Bing  from Chengdu Institute of Biology, CAS was visiting the fern herbarium of Yunnan University, Kunming (PYU), a specimen of Polystichum (Dryopteridaceae) came into his attention. The unique locality and morphological characters of the specimen made him believe that should be a new species. In the following year, ZHANG Liang  (Chengdu Institute of Biology, CAS) visited the locality given on the PYU specimen from Hainan, found the species and collected a few more specimens and DNA material. A molecular study based on the DNA sequences of chloroplast trnL-F intergenic spacer confirms that it is a species unknown to science. The species was described as Polystichum hainanicola Li Bing Zhang, Li Zhang & X. F. Gao.

Polystichum hainanicola is known only from Jiulong Shan in adjacent Guangba and Wangxia towns in western Hainan. Jiulong Shan is a limestone mountain along Changhua Jiang, the second largest river in Hainan. Along the river there are a number of such limestone mountains. It is possible that the new species occurs in additional limestone mountains around Changhua Jiang in western Hainan that are yet to be explored.

The species epithet is from the Chinese pinyin, hainan, the name of a province in southernmost China, and the Latin suffix -cola, inhabiting, referring to the province where the type was collected.

Polystichum hainanicola has once-pinnate fronds and is similar to P. guangxiense, but the former has pinnae with a length to width ratio of 2.5–2.7, lamina completely fertile and sori fewer than four above midrib of middle pinnae. In contrast, the latter has pinnae with a length to width ratio of ca. 3:1, lamina sterile in its lower portion and sori 6–11 above midrib of middle pinnae. Based on a phylogenetic analysis of chloroplast gene trnL-F, the closest relatives of P. hainanicola were not found

The paper entitled “Polystichum hainanicola (Dryopteridaceae), a new fern species from Hainan Island, China” was published online in Phytotaxa 85(1): 9–14 (2013)(http://www.mapress.com/phytotaxa/content/2013/f/p00085p014f.pdf)