Revisión del género Danaea (Marattiaceae - Pteridophyta)

Abstract

This is a revision of Danaea , the only neotropical genus of the Marattiaceae. Several collections were analized, and both external and internal detailed morphology of the sporophyte was studied. Taxonomy of the species, a key to identify them, comments on their affinities, geographical distribution, altitudinal range, cytology and ecology are also given. Seventeen species of the genus are recognized: D. alata, D. carillensis, D. crispa, D. elliptica, D. humilis, D. imbricata, D. jenmanii, D. mazeana, D. moritziana, D. nodosa, D. oblanceolata, D. plicata, D. simplicifolia, D. tenera, D. trichomanoides, D. ulei and D. wendlandii . Danaea shares several characters with the other four marattiaceous genera ( Angiopteris, Archangiopteris, Christensenia and Marattia ), as naked, carnose polycyclostelic amylaceous rhizomes with internal collenchymatous tissues, excentric simple starch grains, geminate stipules, pulvinules, types of epidermal patterns of the laminae, marattiaceous stomata, presence of intercellular pectic protuberances in the mesophyll cells (IPP), and mucilage secreting system. However, postrate and erect rhizomes; number of pulvinules in the stipes; simple or 1-pinnate, dimorphic laminae; pinna outline; entire, undulate or crispate pinna margins; glandular indument (both mucilaginiferous trichomes and protoscales); lamina texture; venation patterns; epidermal patterns of the epiphylls and hypophylls which vary at the specific level; both normal and porocyclocytic marattiaceous stomata; mostly filamentose IPP, and the morphology of the exopore in echinate spores are considered good diagnostic characters related to Danaea . Division of the lamina, indument, lamina and pinna outline, number of pinnae, type of pinna margin, lamina texture, venation patterns, presence or absence of terminal pinnae or gemae, and color of veins and the hypophylls are good morphological characteres to identify the species both in fresh and dry specimens, and they were used to prepare the key to identify the species, along with other traits such as rhizome types, which can be additionally useful to complete plant identifications in the field.