Plastid genomes display remarkable organizational stability over evolutionary time. From green algae to angiosperms, most plastid genomes are largely collinear, with only a few cases of inversion, gene loss, or, in extremely rare cases, gene addition. These plastome insertions are mostly clade-specific and are typically of nuclear or mitochondrial origin. Here, we expand on these findings and present the first family-level survey of plastome evolution in ferns, revealing a novel suite of dynamic mobile elements. Comparative plastome analyses of the Pteridaceae expose several mobile open reading frames that vary in sequence length, insertion site, and configuration among sampled taxa. Even between close relatives, the presence and location of these elements is widely variable when viewed in a phylogenetic context. We characterize these elements and refer to them collectively as Mobile Open Reading Frames in Fern Organelles (MORFFO). We further note that the presence of MORFFO is not restricted to Pteridaceae, but is found across ferns and other plant clades. MORFFO elements are regularly associated with inversions, intergenic expansions, and changes to the inverted repeats. They likewise appear to be present in mitochondrial and nuclear genomes of ferns, indicating that they can move between genomic compartments with relative ease. The origins and functions of these mobile elements are unknown, but MORFFO appears to be a major driver of structural genome evolution in the plastomes of ferns, and possibly other groups of plants.

Tibouchina (Melastomataceae: Melastomateae) is an exclusively Neotropical genus that currently includes close to 310 species. These were first described or assigned to 16 other genera, a reflection of the complex taxonomic and phylogenetic history of the genus. Previous phylogenetic analyses have shown that the genus is polyphyletic. Here we present an expanded analysis that includes representatives of 28 genera of New World Melastomateae, as well as representatives of Old World Melastomateae and members of the Marcetieae and Microlicieae. Over 300 species were sequenced for nrITS and the plastid spacers accD‐psaI and psbK‐psbL. We recovered a large clade of Neotropical Melastomateae that contains Tibouchina along with at least 13 other Neotropical genera. Moreover, Tibouchina is not recovered as monophyletic because three mostly Central American and five mostly Andean genera are nested within it, albeit each these genera are recovered as monophyletic. Many of the previously recognized sections of Tibouchina are recovered as monophyletic or paraphyletic providing a basis for a new classification. Tibouchina is here re‐circumscribed into four genera that are each monophyletic and easily diagnosable. This results in a narrowly circumscribed Tibouchina and the re‐establishment of Pleroma and Chaetogastra, and the description of a new genus, Andesanthus. Pleroma now also includes Itatiaia, Microlepis and Svitramia. Brachyotum is maintained until its relationship to Chaetogastra can be further examined. This new taxonomic arrangement is more informative and convenient than merging eight other genera into Tibouchina. An identification key, descriptions of genera, and lists of taxa with their current generic assignment and necessary nomenclatural novelties are also presented here.

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Abstract— Ongoing research on the taxonomically complex genus Cheilanthes (Pteridaceae; Cheilanthoideae) has resulted in the identification of a new species from Loja Province in Ecuador, Cheilanthes ecuadorensis, described and illustrated herein. Originally collected in 1988 and identified as C. cf. rufopunctata, C. ecuadorensis is clearly distinct from that species in having pubescent adaxial blade surfaces and narrow, poorly-differentiated false indusia (rather than the glabrous adaxial surfaces and wide false indusia of C. rufopunctata). Among the South American species currently included in Cheilanthes, C. ecuadorensis is superficially most similar to C. pilosa. However, our molecular phylogenetic analyses indicate that C. ecuadorensis is sister to C. micropteris, the morphologically disparate generitype of Cheilanthes. Here we examine the phylogenetic relationships, morphology, cytogenetics, and geography of these four South American Cheilanthes species in a study that, once again, highlights the importance of herbaria in the process of new species discovery.

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