A plastid phylogeny of the Old World fern genus Leptochilus (Polypodiaceae): Implications for cryptic speciation and progressive colonization from lower to higher latitudes.

The newly defined fern genus Leptochilus contains about 50 species occurring in subtropical to tropical Asia and adjacent Pacific islands. The circumscription and phylogeny of the genus have been ambiguous and its species had been included in various genera such as Colysis, Dendroglossa, Kontumia, Microsorum, and Paraleptochilus. Previous molecular studies sampled only 2-4 molecular markers and 2-16 accessions of Leptochilus. In the present study, DNA sequences of six plastid markers of 105 accessions representing ca. 40 species of Leptochilus, including types of Colysis, Kontumia, Leptochilus, and Paraleptochilus, 39 species of six non-Leptochilus genera of Microsoroideae, and one species of Pyrrosia, are used to infer a phylogeny. Our major results include: (1) Leptochilus is monophyletic and resolved as nested within the microsoroid ferns, but its relationships with other members of Microsoroideae are not well resolved; (2) Six well-supported major clades in Leptochilus are recognized, differing from one another in molecular, morphological, and geographical features; (3) Species related to L. macrophyllus representing earliest split in Leptochilus are identified; (4) The inclusion of Microsorum pteropus in Leptochilus is confirmed, whereas M. insigne is closely related to Leptochilus but not resolved as a member of the genus; (5) The species number of the genus is likely to double the most recent estimate following our study, and quite a few cryptic species should be recognized; and (6) A basal grade formed by three major clades is recovered and they are composed of species almost exclusively distributed at lower latitudes (the Malay Archipelago), whereas the shallow-level clades contain species distributed at mainly higher latitudes, suggesting that Leptochilus might have evolved at lower latitudes and progressively dispersed to and colonized higher latitudes.

A plastid phylogeny and character evolution of the Old World fern genus Pyrrosia (Polypodiaceae) with the description of a new genus: Hovenkampia (Polypodiaceae).

The Old World fern genus Pyrrosia (Polypodiaceae) offers a rare system in ferns to study morphological evolution because almost all species of this genus are well studied for their morphology, anatomy, and spore features, and various hypotheses have been proposed in terms of the phylogeny and evolution in this genus. However, the molecular phylogeny of the genus lags behind. The monophyly of the genus has been uncertain and a modern phylogenetic study of the genus based on molecular data has been lacking. In the present study, DNA sequences of five plastid markers of 220 accessions of Polypodiaceae representing two species of Drymoglossum, 14 species of Platycerium, 50 species of Pyrrosia, and the only species of Saxiglossum (subfamily Platycerioideae), and 12 species of other Polypodiaceae representing the remaining four subfamilies are used to infer a phylogeny of the genus. Major results and conclusions of this study include: (1) Pyrrosia as currently circumscribed is paraphyletic in relation to Platycerium and can be divided into two genera: Pyrrosia s.s. and Hovenkampia (gen. nov.), with Hovenkampia and Platycerium forming a strongly supported clade sister to Pyrrosia s.s.; (2) Subfamily Platycerioideae should contain three genera only, Hovenkampia, Platycerium, and Pyrrosia s.s.; (3) Based on the molecular phylogeny, macromorphology, anatomical features, and spore morphology, four major clades in the genus are identified and three of the four are further resolved into four, four, and six subclades, respectively; (4) Three species, P. angustissima, P. foveolata, and P. mannii, not assigned to any groups by Hovenkamp (1986) because of their unusual morphology, each form monospecific clades; (5) Drymoglossum is not monophyletic and those species previously assigned to this genus are resolved in two different subclades; (6) Saxiglossum is resolved as the first lineage in the Niphopsis clade; and (7) The evolution of ten major morphological characters in the subfamily is inferred based on the phylogeny and various morphological synapomorphies for various clades and subclades are identified.

A global phylogeny of the fern genus Tectaria (Tectariaceae: Polypodiales) based on plastid and nuclear markers identifies major evolutionary lineages and suggests repeated evolution of free venation from anastomosing venation.

Tectaria (Tectariaceae) is one of the most confusing fern genera in terms of its circumscription and phylogeny. Since its original description, a number of genera had been moved into or related with this genus, while others had been segregated from it. Tectaria is also among the largest fern genera, comprising 150-210 mostly tropical species. Previous molecular studies have been far from comprehensive (sampling no more than 76 accessions from 52 species), limited in geographic scope (mainly restricted to Asia), and based exclusively on plastid markers. In the present study, DNA sequences of eight plastid and one nuclear marker of 360 accessions representing ca. 130 species of Tectaria, ca. 36 species of six non-Tectaria genera in Tectariaceae, 12 species of Davalliaceae, Oleandraceae, and Polypodiaceae, and 13 species of Lomariopsidaceae were used to infer a phylogeny with maximum likelihood, Bayesian inference, and maximum parsimony approaches. Our major results include: (1) the most recently proposed circumscription of Tectaria is strongly supported as monophyletic; (2) the genera Lenda, Microbrochis, Phlebiogonium, and Sagenia, sampled here for the first time, are resolved as part of Tectaria; (3) four superclades representing early splits in Tectaria are identified, with the Old World species being sister to the New World species; (4) 12 well-supported major clades in Tectaria are revealed, differing from one another in molecular, morphological, and geographical features; (5) evolution of 13 morphological characters is inferred in a phylogenetic context and morphological synapomorphies of various clades are identified; and in particular (6) free venation in Tectaria is inferred to be repeatedly derived from anastomosing venation, an evolutionary phenomenon not documented previously in vascular plants in a phylogenetic context based on both plastid and nuclear evidence.