Abstract
As recently demonstrated, the group of Adiantum raddianum is monophyletic and can be recognized by round-reniform indusia and veins ending in sinuses at the sterile segment margins. The most related species belong to the A. poiretii group, which is morphologically distinct by the oblong to lunate indusia. In the A. raddianum group sixteen species are recognized in the present work. Among these species, A. patens s.l. is the unique species that occurs in Africa outside the neotropical region. Adiantum raddianum is the broadest distributed species of the group, widely cultivated globally, and it has become naturalized in the Paleotropics and other regions. Typifications are presented for two accepted names: A. lorentzii and A. ruizianum. Several other typifications are also presented for synonymized species. Adiantum alan-smithii, A. galeottianum, A. imbricatum, A. lobatum, A. ruizianum, A. shepherdii and A. subvolubile are species with restricted distributions occurring only in one or two countries. An identification key, as well as descriptions, synonymies, discussion on morphology and taxonomy, illustrations and a list of specimens examined are provided.Citation: Hirai R. Y. & Prado J. 2019: Neotropical species of the Adiantum raddianum group (Pteridaceae). – Willdenowia 49: 295–317. doi: https://doi.org/10.3372/wi.49.49302Version of record first published online on 26 November 2019 ahead of inclusion in December 2019 issue.
Highlights
Adiantum L., commonly known as the maidenhair ferns, belongs to the Pteridaceae, a family with c. 50 genera and 950 species (Smith & al. 2006, 2008)
Tryon & Tryon (1982) in Ferns and allied plants, with special reference to tropical America treated Adiantum in eight informal groups mainly based in the division of the lamina, the pattern of venation, and indument of axes: (1) A. capillus-veneris L
Based on the morphological characters pointed out above, we included in these taxonomic treatment three species that were not sampled in the phylogenetic study by Hirai & al. (2016): Adiantum imbricatum, A. lobatum and A. subvolubile
Summary
Adiantum L., commonly known as the maidenhair ferns, belongs to the Pteridaceae, a family with c. 50 genera and 950 species (Smith & al. 2006, 2008). Hirai & Prado: Neotropical species of the Adiantum raddianum group and morphological data. This group can be recognized by having a unique 66 nucleotide insertion in the chlN gene alignment, morphologically by pseudopedate to 1 – 5-pinnate laminae, sterile segments with veins ending in sinuses at the segment margins and round-reniform sori. Based on the recent phylogenetic advances pointed out above and in order to start to revise the entire genus Adiantum, the present paper has as a main goal to present the taxonomic treatment of the neotropical species of the A. raddianum group. Morphological data were taken from herbarium specimens borrowed from 39 herbaria worldwide (see Acknowledgements) and recent collections by the authors, whose specimens were deposited at the SP Herbarium Some species extend their distribution beyond the neotropical region in the north and south. Based on the morphological characters pointed out above, we included in these taxonomic treatment three species that were not sampled in the phylogenetic study by Hirai & al. (2016): Adiantum imbricatum, A. lobatum and A. subvolubile
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