Morphology of the Eschweilera parvifolia clade
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Title
Morphology of the Eschweilera parvifolia clade
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Authors
Scott Alan Mori, Caroline Carollo, Nathan P. Smith
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Scientific Name
Eschweilera Mart. ex DC.
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Description
From Huang et al. (in review)
Eschweilera parvifolia clade (94% BS; Fig. 1B, Fig. 15)—This clade consists of a sample of 29 of the approximately 63 species (minus the species now considered as belonging to the E. integrifolia clade) recognized by Mori and Prance (1990). Species of this clade are found nearly everywhere in the Neotropics, ranging from Veracruz, Mexico to Rio de Janeiro, Brazil (Huang, 2010).
The sections of Eschweilera, as defined by Mori and Prance (1990), include Eschweilera sect. Tetrapetala (our E. tetrapetala clade discussed above); Eschweilera sect. Jugastrum, consisting only of E. tenuifolia (O. Berg) Miers; Eschweilera sect. bracteosa, consisting of the sampled E. bracteosa (Poepp ex. O. Berg) Miers, E. laevicarpa S. A. Mori, and E. cyathiformis S. A. Mori, and the non-sampled E. rabeliana S. A. Mori and E. revoluta S. A. Mori (Mori, 1990a); and Eschweilera section Eschweilera with the remaining species, including the type E. parvifolia (Mori & Prance, 1990).
Mori and Prance (1990d) included species of our E. integrifolia (described above), E. tetrapetala (described above), and the E. parvifolia clades in their concept of Eschweilera. Based on our results, Eschweilera is not monophyletic, and the type of the genus falls into the E. parvifolia clade.
The most useful morphological synapomorphy of the E. parvifolia clade is the presence of a lateral aril (Figs. 2C, 14F; character 48). Although there are a few species with lateral arils in the E. integrifolia clade, most of those species have spreading arils (Fig. 11C) and the ones with lateral arils are either much larger and/or wrap around the ends of the seeds (Figs. 11A–B, see above discussion of the E. integrifolia clade). In addition, this is the only clade with consistently double-coiled androecial hoods (Fig. 14B, H) in contrast to the consistently single-coiled androecial hoods of the Eschweilera tetrapetala and the triple-coiled androecial hoods of the E. integrifolia clades. The species of the Eschweilera parvifolia and E. integrifolia clades are the only species to have vestigial stamen nectaries in the Bertholletia clade, a feature that is also found outside of the clade in Couratari (Mori et. al., manuscript).
Eschweilera tenuifolia differs from the other species of this clade because it lacks pedicels (character 13) and its seeds do not have an aril (character 47). Other defining features are wedge-shaped seeds; a corky seed coat; and seed germination from the sides instead of the ends of the seeds (not coded). The flowers of E. tenuifolia have a double-coiled androecial hood identical to the other species of the E. parvifolia clade. This species was the only one included in E. section Jugastrum by Mori & Prance (1990) and can only be recognized as a separate section if the poorly understood basal clade (the E. mexicana clade) is also recognized as a section but that clade has no differences from the other species of the Eschweilera parvifolia clade. In this study, the representatives of Eschweilera section Bracteosa fall into two unresolved clades. Whether this section should be recognized is open to question, but it is unlikely that the persistent of bracts and bracteoles in the inflorescences are stable enough for use in defining taxonomic groups (Fig. 1B).
Our study suggests that Eschweilera should be limited to the Eschweilera parvifolia clade, that species in the Eschweilera integrifolia and Eschweilera tetrapetala clades be recognized as separate genera, and that there is no basis for recognizing subgenera within the Eschweilera parvifolia clade.