A taxonomic revision of Plagiochila sect. Hylacoetes, sect. Adiantoideae and sect. Fuscoluteae in the Neotropics with a preliminary subdivision of Neotropical Plagiochilaceae into nine lineages

Currently, 20 section and subsection names are in use for Neotropical Plagiochilae. Phylogenetic analyses of morphological and phytochemical characters as well as of sequence variations of internal transcribed spacer regions of nuclear ribosomal DNA reveal the presence of only 9 monophyletic lineages of Plagiochila (Dumort.) Dumort. in the Neotropics, assignable to the sections Adiantoideae Lindenb., Alternantes Carl, Arrectae Carl, Cucullatae Schiffn., Fuscoluteae Carl, Glaucescentes Carl, Hylacoetes Carl, Rutilantes Carl, and Vagae Lindenb. The illegitime Plagiochila sect. Superbae Carl, which was erected for some of the largest Neotropical species of Plagiochila, disintegrates into P. sect. Hylacoetes and P. sect. Adiantoideae. Members of sect. Hylacoetes are characterized by a capsule wall epidermis without thickenings on the walls and usually fan-shaped, terminal androecia. In contrast, sect. Adiantoideae has a capsule wall epidermis with nodulose cell wall thickenings and simple, intercalary androecia. Sect. Adiantoideae comprises 4 species and is restricted to the Neotropics. Sixteen species (including the new Plagiochila patriciae J. Heinrichs & H. Anton) are recognized within sect. Hylacoetes, which occurs not only in the Neotropics but also in Africa (P. boryana Gottsche ex Steph.). The monospecific genera Szweykowskia Gradst. & M. Reiner and Steereochila Inoue are treated as members of the latter section; Steereochila ecuadorica Inoue is lowered to a variety of P. dimorpha Lindenb. & Gottsche. All 8 species of Plagiochila sect. Fuscoluteae (syn. nov.: P. sect. Bursatae Carl) are characterized by the presence of surface wax. The section is restricted to the Neotropics, with the exception of P. heterophylla Lindenb. ex Lehm., which also occurs in Atlantic Europe, were it was known as P. atlantica F. Rose. Keys to the members of Plagiochila sect. Adiantoideae, Hylacoetes and Fuscoluteae are given and descriptions of gametophytic and sporophytic features as well as distributional and ecological data are provided.