by Robbin Moran, Judith Garrison Hanks, Michael Sundue
The lady ferns (Athyrium s.l.) are primarily distributed in the Old World, but include some New World representatives including Anisocampium, Pseudathyrium, and Athyrium s.s. Most of the New World species and especially those in the Neotropics, have not been subject to phylogenetic investigation. Therefore, we carried out a molecular phylogenetic analysis of Neotropical lady ferns (based on five plastid markers) to investigate their relationships. We sampled Neotropical species of Athyrium s.s. and Anisocampium and combined them with a comprehensive Athyriaceae dataset. Our analyses recovered a clade comprised of three Neotropical species sister to all other lady ferns, including Anisocampium skinneri along with two species thought to be related to it, A. palmense and A. tejeroi. Our results also indicate that the other Neotropical species of Athyrium s.s. are not monophyletic. One of our seven samples belongs to the A. filix-femina clade (sect. Athyrium) which they have always been assumed to be related to, but the remaining six samples are resolved in sect. Mackinnoniana, which is otherwise comprised of Asian species. To accommodate our findings, we describe the A. skinneri clade as a new genus, Ephemeropteris, diagnosed by creeping, distichous rhizomes with internodes 1-2 mm long, and by having thin, membranous laminae and pale reddish petioles, rachises, and costae. Ephemeropteris comprises three species, and new combinations are made: E. palmensis, E. skinneri, and E. tejeroi. These species occur primarily on the Pacific side of Mesoamerica, a region with a highly seasonal climate. Based on month-of-collection data from herbarium specimens, leaf production is shown to be strongly seasonal in E. palmensis and E. skinneri. Seasonality could not be assessed for E. tejeroi because it is known only from two collections. We provide a taxonomic treatment of the three species of Ephemeropteris. The treatment contains keys, descriptions, illustrations, nomenclatural data, specimens cited, and dot-distribution maps.