Taxonomic Revision of the Petiolatum Clade of Elaphoglossum sect. Lepidoglossa (Dryopteridaceae)

This paper provides a monograph of the petiolatum clade of Elaphoglossum Schott ex J. Sm. sect. Lepidoglossa Christ (Dryopteridaceae). This group has been recovered as monophyletic in several molecular phylogenetic analyses. Morphologically, the petiolatum clade is recognized by laminae with resinous dots and flat and/or stellate scales, rhizome scales with acute to filiform-tortuous apices, scales on the proximal portion of the petiole with dark apices, and perines broadly folded, sparsely echinulate with spines less than 1 μm high, or (in E. petiolatum (Sw.) Urb.) with sparse irregular microstructures. Eight species are recognized as a part of the clade, all of them distributed in the American tropics from Mexico to Panama, and one species in the Greater Antilles. Most of the species occur between 1000 and 2500 m elevation in tropical, temperate, and pine-oak forests. Presented here are an identification key, a full synonymy, detailed descriptions, a list of specimens examined, an index to collectors’ names and collection numbers, images of the plants and their main structures, spore microphotographs, and distribution maps for all species. A new combination is made for E. schmitzii (Mett. ex Kuhn) Martínez-Bec. & A. Vasco, and lectotypes are designated for Acrostichum intermedium Fée, E. muelleri (E. Fourn.) C. Chr., E. potosianum Christ, E. pringlei (Davenp.) C. Chr., and E. schmitzii.