Background and Aims The dynamics of genome evolution caused by whole genome duplications and other processes are hypothesized to shape the diversification of plants and thus contribute to the astonishing variation in species richness among the main lineages of land plants. Ferns, the second most species rich lineages of land plants are highly suitable to test this hypothesis because of several unique features that distinguish fern genomes from those of seed plants. In this study, we tested the hypothesis that genome diversity and disparity shape fern species diversity by recording several parameters related to genome size and chromosome number. Methods We conducted de novo measurement of DNA C-values across the fern phylogeny to reconstruct the phylogenetic history of the genome space occupation in ferns by integrating genomic parameters such as genome size, chromosome number, and average DNA amount per chromosome into a time-scaled phylogenetic framework. Using phylogenetic generalized least square methods, we determined correlations between chromosome number and genome size, species diversity and evolutionary rates of their transformation. Key Results The measurements of DNA C-values for 233 species more than doubled the taxon coverage from ca. 2.2% in previous studies to 5.3% of extant diversity. The dataset documented not only substantial differences in the accumulation of genomic diversity and disparity among the major lineages of ferns but also recovered support the predicted correlation between species diversity and the dynamics of genome evolution. Conclusions Our results demonstrated substantial genome disparity among different groups in ferns and supported the prediction that alterations of reproductive modes alter trends of genome evolution. Finally, we recovered evidence for a close link between the dynamics of genome evolution and species diversity in ferns for the first time.

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Introducción y objetivos: Algunas especies de helechos cheilanthoideos son caracterizados por presentar adaptaciones a hábitats xéricos. Además, presentan la particularidad de enrollar sus láminas frente a condiciones de stress hídrico. Sin embargo, al retornar las condiciones ambientales óptimas las láminas se vuelven a expandir. El objetivo de este trabajo es proporcionar información morfo-anatómica de las frondes y asociar estructuras anatómicas a estos movimientos foliares.M&M: Se estudiaron mediante microscopía óptica y electrónica de barrido la morfo-anatomía de las frondes de cuatro especies: Adiantopsis radiata, Cheilanthes glauca, Doryopteris concolor, y D. pentagona. Además, se analizó la densidad de los estomas y se calculó el índice estomático.Resultados: Se observó mesófilo homogéneo en A. radiata y D. pentagona. Cheilanthes glauca y Doryopteris concolor presentaron mesófilo heterogéneo dorsiventral. Todas las especies mostraron hojas hipoestómaticas y estomas de tipo anomocítico. El índice estomático osciló entre 9,1% (A. radiata) y 14,1% (D. concolor) y el rango de densidad de los estomas fue de 39,7 (D. pentagona) y 57,8 (D. concolor).Conclusiones: El mesófilo observado en A. radiata y D. pentagona refleja la especialización para habitar ambientes mesófilos. El mesófilo heterogéneo dorsiventral de Doryopteris concolor podría ser una ventaja para su hábito epifítico facultativo. Cheilanthes glauca tiene características xeromorfas y mesomorfas, probablemente como resultado de la disponibilidad de agua en el ambiente durante las diferentes estaciones. Se propone como hipótesis que el engrosamiento de las paredes anticlinales de las células epidérmicas podría estar involucrados en los movimientos de las láminas.

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The objective of this exploratory work is to test the hypothesis that South American populations of Ophioglossum reticulatum L. derive from Africa. Spores cross the Atlantic transported by wind and arrive in South America in recurrent migration. Three-dimensional (backward and forward) trajectories of spores between Africa and South America were calculated using the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT4). The model showed possible backward trajectories in the low troposphere arriving in South America with probable origin in Northwestern Africa. The results support the hypothesis of long-distance dispersal of the studied species. Including vertical motion in the model runs allowed obtaining valuable and novel information about the migration routes. The trade winds combined with the South American monsoon could be a dispersal vehicle for the disseminules from Northwestern Africa to the eastern slopes of the Andes. As the monsoon is a periodic regional atmospheric circulation pattern, transcontinental migration can be assumed to be a recurring phenomenon that provides genetic exchange and prevents speciation by reproductive isolation. Modelled forward trajectories connect the neotropics with Africa-Madagascar, but they seem to be less effective due to their travelling altitudes. This hypothesis might explain the absence of infraspecific taxa restricted to different geographic locations.

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The genus Ophioglossum has around 25 species with a nearly cosmopolitan distribution. It has historically posed a number of taxonomic problems due to the lack of morphological characters upon which to base species delimitations. In order to address this, we analyzed the sculpture patterns of spores from ten critical taxa from southern South America. Palynological data was compared with the morphology of the sporophyte. The sculpturing pattern was the most valuable and consistent taxonomic character upon which to base species delimitation in Ophioglossum. Nomenclatural types of studied species were examined. The name Ophioglossum melipillense is reinstated and the other species recognized to the genus Ophioglossum s.s. in this region are the following: O. crotalophoroides, O. nudicaule, O. opacum, and O. vulgatum. Ophioglossum fernandezianum appears to be a doubtful species. Ophioglossum lusitanicum is excluded from the study area, but the lectotype of O. lusitanicum is designated, and a revised synonymy is presented.

<div><span style="font-family: Arial, Helvetica, sans-serif; font-size: 12px; color: #666666;">La presencia de&nbsp;<em>Doryopteris lomariacea&nbsp;</em>Kunze ex Klotzsch (Pteridaceae) se confirma por primera vez para Argentina, restringida a la provincia de Misiones. La especie se describe e ilustra la misma, se analizan las esporas y se aportan observaciones ecol&oacute;gicas.</span></div>