Search

The fern genus Hymenasplenium (Aspleniaceae) is one of the two genera in the family. It is generally recognized among modern pteridologists. However, its infrageneric relationships and species diversity have been unclear and controversial. The molecular studies so far have had small taxon and character sampling. In the present study, DNA sequences of six plastid markers of 158 accessions representing ca. 40 out of ca. 50 known species of Hymenasplenium , and 16 species of Asplenium were used to infer a phylogeny with maximum likelihood, Bayesian inference, and maximum parsimony approaches. Our major results include: (1) Hymenasplenium as currently defined is strongly supported as monophyletic; (2) three major clades representing early splits in Hymenasplenium are identified, with the Old World species being strongly supported as monophyletic; it is ambiguous if the New World species are monophyletic; (3) extensive cryptic speciation in the Old World is discovered demonstrating the complexity of evolution of the genus; and (4) six strongly or moderately supported subclades in the Old World clade are revealed, differing from one another in molecular, morphological, and geographical features. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hypodematiaceae are found to be sister to the remaining eupolypods I. • Hypodematium is resolved into seven clades. • A latest Jurassic-earliest Cretaceous origin of the family and an Upper Cretaceous origin of two genera are inferred. • Hypodematium appears to have originated from East Asia and dispersed to Africa and Southeast Asia. • Leucostegia appears to have originated from Southeast Asia and/or East Asia. The Old World fern genera Hypodematium and Leucostegia had long been placed in the families Dryopteridaceae and Davalliaceae, respectively, before the advent of molecular phylogenetics. Recent molecular studies confirmed the recognition of the family Hypodematiaceae composed of these two genera, but the relationships within each of these two genera have been unclear. In the present study we performed phylogenetic analyses (MP, ML, BI) based on DNA data from six plastid markers (atpB , atpB-rbcL , matK , rbcL , rps4 & rps4-trnS , and trnL & trnL-F) of 165 accessions representing 31 species in two genera of Hypodematiaceae as the ingroup and 26 accessions representing Cystopteridaceae, Didymochlaenaceae, Dryopteridaceae, Davalliaceae, Oleandraceae, and Woodsiaceae as the outgroups. Our analyses supported the monophyly of the currently defined Hypodematiaceae only including Hypodematium and Leucostegia and found that the family to be sister to the remaining eupolypods I. Our data resolved three taxa of Leucostegia into two clades. In Hypodematium , 28 taxa are resolved into seven strongly supported clades or single-accession clades. The evolution of important morphological characters are inferred in the phylogenetic context. Our dated phylogeny suggested a latest Jurassic-earliest Cretaceous origin of the family and Upper Cretaceous origin of two genera, with Hypodematiaceae originated from East Asia; extant lineages of Hypodematium originated from East Asia and subsequently into Africa, the Indian region, the Madagascar region, and Southeast Asia; and Leucostegia originated from East Asia and/or Southeast Asia. [ABSTRACT FROM AUTHOR]