Data from: Pteris borneensis (Pteridaceae), a New Species from Borneo, with Re-circumscription of Pteris decrescens and Pteris parviloba

A new species was collected during a fern expedition in Nuluhon Trusmadi Forest Reserve, Sabah, Borneo. Morphologically, it is similar to both Pteris decrescens Christ and P. parviloba Christ but can be distinguished by the frond characters. Specifically, the new species differs from the other two species by having basiscopic secondary pinnae (vs. without basiscopic secondary pinnae), petiolulate pinnae (vs. sessile pinnae), without bristles on the stipes (vs. with bristles on the stipes), a crenate margin of the pinna-segment apex (vs. a serrate apex), and entire pseudoindusia (vs. ciliate pseudoindusia). Furthermore, P. decrescens and P. parviloba differ in the number of lateral pinnae (5 or 6 vs. 8–16 pairs) and the length of the basal pinna-segments being shortest or longest of all lateral pinnae. Two plastid genes, rbcL and matK, were used to decipher their phylogenetic relationships. The new species was resolved in different clades from P. decrescens and P. parviloba, providing further support of its uniqueness. The morphology, illustrations, ecology, and distribution of the new species are provided. We also found that the type materials of P. decrescens included two different species, P. decrescens and P. parviloba. A lectotype of P. decrescens was therefore designated. Based on the results of this study, P. decrescens and P. parviloba are re-circumscribed, and the new species is described as P. borneensis sp. nov.

本研究在婆罗洲沙巴的努卢洪·特鲁斯马迪森林保护区开展蕨类植物考察期间，采集到一个新物种。形态学上，该新种与德氏凤尾蕨（Pteris decrescens Christ）和小叶凤尾蕨（Pteris parviloba Christ）均较为相似，但可通过蕨叶特征加以区分。具体而言，该新物种与二者的差异体现在：具基生次小羽片（对比二者无基生次小羽片）、小羽片具短柄（对比二者小羽片无柄）、叶柄无刚毛（对比二者叶柄具刚毛）、小羽片裂片先端具圆齿（对比二者先端具锯齿），以及假囊群盖全缘（对比二者假囊群盖具纤毛）。此外，德氏凤尾蕨与小叶凤尾蕨在侧生小羽片数量（5或6对 vs. 8~16对）以及基部小羽片裂片的长度（为所有侧生小羽片中最短或最长）上存在差异。本研究利用2个质体基因rbcL与matK解析了其系统发育关系。该新物种与德氏凤尾蕨、小叶凤尾蕨处于不同的演化支，进一步证实了其分类独特性。本研究提供了该新物种的形态学特征、形态图解、生态习性与分布信息。同时研究团队发现，德氏凤尾蕨的模式标本包含两个不同物种，即德氏凤尾蕨与小叶凤尾蕨。因此我们指定了德氏凤尾蕨的后选模式标本。基于本研究结果，我们重新界定了德氏凤尾蕨与小叶凤尾蕨的分类范畴，并将该新物种正式描述为婆罗洲凤尾蕨（Pteris borneensis sp. nov.）。