Finding missing diversity from synonyms of (Pteridaceae).

Although taxonomists target the remote wild regions to discover new species, taxa lacking a comprehensive and modern systematic treatment may be the new hotspot for biodiversity discovery. The development of molecular systematics integrated with microscopic observation techniques has greatly improved the ability of taxonomists to identify species correctly. Ching ex J.F. Cheng, regarded as a synonym of (Makino) E.H.Crane, remained hidden from the eyes of fern taxonomists for more than 20 years. Herein, we collected several population samples of by performing molecular phylogenetic analysis of five cpDNA regions (, , , , and ) and through micromophological observation of specimens which differs from by lamina width and exospores. Considering the differences in morphology, geographical range, and genetic distance between these two species, we formally recognized as an authentic species and proposed a new combination (Ching ex J.F.Cheng) Y.H.Yan, Z.Y.Wei & X.C.Zhang, Our findings demonstrate that several taxa in synonyms are missing, and nowadays taxonomy should also include re-evaluation of the past taxonomy.