Leptosporangiate Ferns Research Articles

Ultrastructural Studies of Oogenesis in the Fern Diplopterygium glaucum

The present investigation examines the oogenesis of the gleichenioid fern, Diplopterygium glaucum (Thunb. ex Houtt.) Nakai using transmission electron microscopy. The results demonstrate that the oogenesis of D. glaucum is similar to the core leptosporangiate ferns. The egg cell of D. glaucum was progressively isolated from the adjacent cells by forming a separation cavity and an egg envelope during maturation. However, during this process, a pore region consistently connected the egg and the ventral canal cell. Ultimately, a fertilization pore formed at the pore region when the egg matured. The nucleus produced conspicuous evaginations during later stages of egg development. The cytological features during oogenesis in D. glaucum more closely resembled the core leptosporangiate ferns rather than the basal leptosporangiate ferns (Lygodium and Osmunda), which possess no egg envelope or fertilization pore. The results provide new characteristics for interpreting the evolutionary history of the gleichenioid ferns.

A multi‐character analysis of Struthiopteris leads to the rescue of Spicantopsis (Blechnaceae, Polypodiopsida)

The family Blechnaceae is a moderately sized leptosporangiate fern lineage, with 24 genera and around 250 species. Struthiopteris accommodates small to medium‐sized, dimorphic, pinnate species. It is composed of six northern species: S. spicant is distributed in western parts of Europe and North America; S. fallax is endemic to Iceland; S. niponica, S. amabilis and S. castanea are endemic to Japan, and S. hancockii occurs in Japan and Taiwan. Due to the lack of a global review and to its highly interesting geographical distribution, this genus merits further study to clarify its taxonomy, species relationships, and distributional pattern. The present study aims to achieve the following goals: (a) identify and describe morphological characters supporting the taxonomy of Struthiopteris; (b) reconstruct a complete phylogeny for the genus; (c) study the biogeographical history of Struthiopteris at a global scale. The morphological study involved the observation of characters ranging from rhizome scales to spores over 164 individuals. Phylogenies were constructed applying ML and BI techniques over 51 newly produced sequences of three chloroplast markers (rbcL, trnL‐trnF, psbA‐trnH), using the species Blechnidium melanopus and Brainea insignis as closest relatives. For the molecular dating and historical biogeography analyses, we estimated and compared ancestral ranges under several models. Most of the morphological characters led us to discern two groups of species: the S. spicant group (S. spicant, S. fallax, and S. castanea) and the S. niponica group (the remaining species). In our molecular phylogeny, the supposed sister genus Blechnidium always appeared as nested within Struthiopteris, rendering this genus non‐monophyletic. The two groups identified by the morphology appeared as monophyletic clades within Struthiopteris, with the clade S. spicant more closely related to Blechnidium than to the clade S. niponica. For all these reasons, we propose to rescue the now‐disused genus Spicantopsis for the species belonging to the S. niponica group: indeed, this genus was created c. 100 years ago to reunite the same species S. amabilis, S. niponica, and S. hancockii. Our results suggest that all members of this group of genera (Blechnidium, Struthiopteris, Spicantopsis) emerged in East Asia about 85 mya, at a time when Japan was still part of the mainland. It appears that, for most of their history, the members of these genera have been confined to East Asia, with one dispersal to the Americas by an ancestor within Struthiopteris s.str., and additional dispersals to India and the Philippines by Blechnidium melanopus.

Full plastome sequence of the fern Vandenboschia speciosa (Hymenophyllales): structural singularities and evolutionary insights.

We provide here the first full chloroplast genome sequence, i.e., the plastome, for a species belonging to the fern order Hymenophyllales. The phylogenetic position of this order within leptosporangiate ferns, together with the general scarcity of information about fern plastomes, places this research as a valuable study on the analysis of the diversity of plastomes throughout fern evolution. Gene content of V. speciosa plastome was similar to that in most ferns, although there were some characteristic gene losses and lineage-specific differences. In addition, an important number of genes required U to C RNA editing for proper protein translation and two genes showed start codons alternative to the canonical AUG (AUA). Concerning gene order, V. speciosa shared the specific 30-kb inversion of euphyllophytes plastomes and the 3.3-kb inversion of fern plastomes, keeping the ancestral gene order shared by eusporangiate and early leptosporangiate ferns. Conversely, V. speciosa has expanded IR regions comprising the rps7, rps12, ndhB and trnL genes in addition to rRNA and other tRNA genes, a condition shared with several eusporangiate ferns, lycophytes and hornworts, as well as most seed plants.

The complete plastid genome sequence of Trichomanes trollii (Hymenophyllaceae)

Plastid genomes have become an important source of information for clarifying phylogenetic relationships especially where traditional molecular systematic studies have failed to produce strongly supported hypotheses. The exact phylogenetic position of an early diverging fern order Hymenophyllales has remained uncertain due to poor support in published phylogenetic studies. High‐throughput sequencing of the first complete plastid genome of the genus Trichomanes revealed genome structure similar to the closest relatives and the phylogenetic analysis resulted in equally poorly supported topology as the previous studies that were based on only a few molecular markers. It seems that, at least with the current poor taxonomic sampling of complete plastid genomes, the exact relationships between Hymenophyllales, Gleicheniales, and other nonosmundalean leptosporangiate ferns cannot be firmly established.

One forgotten name, and another misinterpreted, in Lomariocycas (Blechnaceae, Polypodiopsida)

Blechnaceae Newman (1844: 8) is a subcosmopolitan family of leptosporangiate ferns (Polypodiopsida), which comprises around 250 species (Pteridophyte Phylogeny Group 2016). Until recently, most of this diversity fell under one, large genus Blechnum Linnaeus (1753: 1077), but after the accumulation of strong evidence of its non-monophyletic status (Shepherd et al. 2007, Gabriel y Galán et al. 2013, Perrie et al. 2014, Gasper et al. 2017), it was split into several entities. Thus, in its current conception, Blechnaceae is formed by 24 genera (Pteridophte Phylogeny Group 2016).

The fern family Gleicheniaceae (Polypodiopsida) in Brazil

We carried out a taxonomic study of the leptosporangiate fern family Gleicheniaceae (Polypodiopsida) in Brazil out and accepted 17 species distributed in three genera. Taxonomic descriptions to the whole family, genera and species are provided, as well as keys to the genera and species, synonymies, maps, illustrations, and notes. We also provide nomenclatural notes and propose 21 lectotypes.

Morfogénesis de la fase sexual de los helechos epífitos Microgramma mortoniana y Pleopeltis macrocarpa (Polypodiaceae) reserva Natural Punta Lara, Buenos Aires, Argentina

The Punta Lara Natural Reserve is located on the riverside of the La Plata River in the province of Buenos Aires, Argentina. It is the Southern most relict in the world of subtropical riparian forest. The epiphytic ferns studied in this work belong to the Polypodiaceae family: Microgramma mortoniana and Pleopeltis macrocarpa. Plant communities are subject to high levels of anthropization and introduction of exotic species. The goals of this work are to provide information on the morphogenesis of epiphytic gametophytes and to extend knowledge of their life cycles, contributing to their conservation. Sowing was carried out in Dyer medium. In both species the spores are monolete, ellipsoidal, yellowish and with verrucate sculpture. The equatorial diameter is 60-61 μm, the polar diameter is 39-42 μm. The germination is the Vittaria type; in M. mortoniana occurs at 20 days, while in P. macrocarpa occurs at six days. The filaments are uniseriate of 3-6 cells in length. The gametophyte development is Drynaria type. The cordated form is given after 40 days. In M. mortoniana, buds originated after 40 days. In P. macrocarpa, after 120 days, clathrate trichomes scale-like appear mainly on the margins of the gametophyte. The gametangia are typical of leptosporangiate ferns. The sporophyte of M. mortoniana emerged after 120 days and that of P. macrocarpa arose after 500 days, its blades are simple, spatulate and unicellular and multicellular branching hairs were observed. The germination pattern, gametophyte development, the presence of a lipid globule in the prothalic cell and the formation of unicellular capitated hairs are relevant characters that could be considered for systematic group. The delay in the formation of sporophytes through sexual reproduction, allows us to infer that the success of their establishment in situ would be given by the vegetative reproduction through creeping rhizomes and buds of gametophytes.

The complete chloroplast genome of the invasive fern Lygodium microphyllum (Cav.) R. Br.

The Old World climbing fern, Lygodium microphyllum, is a rapidly spreading environmental weed in Florida, United States. We reconstructed the complete chloroplast genome of L. microphyllum from Illumina whole-genome shotgun sequencing, and investigate the phylogenetic placement of this species within the Leptosporangiate ferns. The chloroplast genome is 158,891 bp and contains 87 protein-coding genes, four rRNA genes, and 27 tRNA genes. Thirty-three genes contained internal stop codons, a common feature in Leptosporangiate fern genomes. The L. microphyllum genome has been deposited in GenBank under accession number MG761729.

Plastid phylogenomic analysis of green plants: A billion years of evolutionary history.

For the past one billion years, green plants (Viridiplantae) have dominated global ecosystems, yet many key branches in their evolutionary history remain poorly resolved. Using the largest analysis of Viridiplantae based on plastid genome sequences to date, we examined the phylogeny and implications for morphological evolution at key nodes. We analyzed amino acid sequences from protein-coding genes from complete (or nearly complete) plastomes for 1879 taxa, including representatives across all major clades of Viridiplantae. Much of the data used was derived from transcriptomes from the One Thousand Plants Project (1KP); other data were taken from GenBank. Our results largely agree with previous plastid-based analyses. Noteworthy results include (1) the position of Zygnematophyceae as sister to land plants (Embryophyta), (2) a bryophyte clade (hornworts, mosses + liverworts), (3) Equisetum + Psilotaceae as sister to Marattiales + leptosporangiate ferns, (4) cycads + Ginkgo as sister to the remaining extant gymnosperms, within which Gnetophyta are placed within conifers as sister to non-Pinaceae (Gne-Cup hypothesis), and (5) Amborella, followed by water lilies (Nymphaeales), as successive sisters to all other extant angiosperms. Within angiosperms, there is support for Mesangiospermae, a clade that comprises magnoliids, Chloranthales, monocots, Ceratophyllum, and eudicots. The placements of Ceratophyllum and Dilleniaceae remain problematic. Within Pentapetalae, two major clades (superasterids and superrosids) are recovered. This plastid data set provides an important resource for elucidating morphological evolution, dating divergence times in Viridiplantae, comparisons with emerging nuclear phylogenies, and analyses of molecular evolutionary patterns and dynamics of the plastid genome.

MIDDLE JURASSIC FLORA FROM THE HOJEDK FORMATION OF TABAS, CENTRAL EAST IRAN: BIOSTRATIGRAPHY AND PALAEOCLIMATE IMPLICATIONS

The Middle Jurassic deposits of the Shemshak Group and Hojedk Formation are widespread in North, Central, and Central East Iran. In this paper, the Hojedk Formation in South Kouchekali, southwestern Tabas city, east-central Iran was studied for palaeobotany and stratigraphy. This formation contains well preserved plant macrofossils belonging to 43 species assigned to 24 genera of various orders such as Equisetales, Filicales, Bennettitales, Cycadales, Caytoniales, Ginkgoales and Pinales. One biozone and four subzones are recognized. The lower and the upper boundaries of this assemblage biozone are identified by the first and the last observed occurrences of Coniopteris hymenophylloides (Brongniart) Seward 1900 and Klukia exilis (Phillips) Raciborski 1890, respectively. According to the occurrences of these index species and Ptilophyllum harrisianum Kilpper 1968 and Nilssonia macrophylla Jacob & Shukla 1955, an early Middle Jurassic (Aalenian-Bajocian) age is considered for this assemblage biozone. Moreover, a comparative biostratigraphy for the Middle Jurassic of Iran is suggested. As a result, the Coniopteris hymenophylloides-Klukia exilis Assemblage biozone is proposed as a biozone widespread through the whole Iranian Plate. On the basis of the relative abundance of Filicales, Pinales, Cycadales, and Equisetales and of the high diversity and abundance of macrophyllous cycadophytes (eight species), a humid sub-tropical climate is suggested for this locality. In addition, floral gradient, correspondence analysis and similarity index were considered. Therefore, it is confirmed that a uniform palaeoclimate and vegetation cover occurred in Iran during the Middle Jurassic and that Iran was located within Vakhrameev's Euro-Sinian Region.

A novel chloroplast gene reported for flagellate plants

Gene space in plant plastid genomes is well characterized and annotated, yet we discovered an unrecognized open reading frame (ORF) in the fern lineage that is conserved across flagellate plants. We initially detected a putative uncharacterized ORF by the existence of a highly conserved region between rps16 and matK in a series of matK alignments of leptosporangiate ferns. We mined available plastid genomes for this ORF, which we now refer to as ycf94, to infer evolutionary selection pressures and assist in functional prediction. To further examine the transcription of ycf94, we assembled the plastid genome and sequenced the transcriptome of the leptosporangiate fern Adiantum shastense Huiet & A.R. Sm. The ycf94 predicted protein has a distinct transmembrane domain but with no sequence homology to other proteins with known function. The nonsynonymous/synonymous substitution rate ratio of ycf94 is on par with other fern plastid protein-encoding genes, and additional homologs can be found in a few lycophyte, moss, hornwort, and liverwort plastid genomes. Homologs of ycf94 were not found in seed plants. In addition, we report a high level of RNA editing for ycf94 transcripts-a hallmark of protein-coding genes in fern plastomes. The degree of sequence conservation, together with the presence of a distinct transmembrane domain and RNA-editing sites, suggests that ycf94 is a protein-coding gene of functional significance in ferns and, potentially, bryophytes and lycophytes. However, the origin and exact function of this gene require further investigation.

Phylogenetics and historical biogeography of Lomaridium (Blechnaceae: Polypodiopsida)

AbstractBlechnaceae is a worldwide family of leptosporangiate ferns composed of about 250 species. Most of the species in the family were recognised under a single large genus Blechnum until recently, when a new classification proposed the recognition of 24 genera. Given this new systematics of Blechnaceae, which largely resolves the genus‐level relationships in the family, there is a need for phylogenetic research to investigate relationships within the majority of the newly proposed genera. In this paper, we unravel the phylogenetic relationships and the historical biogeography of the species of Lomaridium, a genus including most of the hemiepiphytic species in the Blechnaceae. Our sampling includes 11 species, which represents 85% of the diversity in the genus and which covers the entire geographic distribution of the group. We constructed two datasets with three plastid markers: one for phylogenetic analyses (maximum likelihood, Bayesian inference) with four outgroups from phylogenetically close genera (Brainea, Lomaria, Sadleria, Woodwardi); and a second for molecular dating and historical biogeographic analyses that included a larger set of outgroups so that we could accurately reconstruct ancestral events at the base of Lomaridium, under different models. We are able to recognize four highly supported lineages: L. contiguum and the L. schottii, L. attenuatum, and L. fragile clades. Our results date the origin of Lomaridium at some point during the Paleocene epoch, and the most likely geographic area for its origin is Australia plus tropical Central and South America. Several dispersal events are inferred, all of which are most likely long‐distance dispersal events. From Australia, we infer a first dispersal event that brought the ancestor of the extant species L. contiguum to New Caledonia. In Central and South America, Lomaridium continued to diversify and colonized additional areas, including the Caribbean (L. binervatum), some Pacific islands (L. schottii), and Africa and Madagascar. While our goal in the current study was not to estimate the biogeographic or diversification history of all Blechnaceae, our analyses do suggest that the early history of the family was complex biogeographically, with extensive long‐distance dispersal events. Lomaridium exemplifies this high dispersal capacity, as a genus with only a modest number of species that have reached far‐flung regions of the globe via numerous long‐distance dispersal events.

Prodromus of a fern flora for Bolivia. XIII. Anemiaceae

We provide a synopsis to the leptosporangiate fern family Anemiaceae in Bolivia. The single genus in the family, Anemia, comprises 115 species in the Neotropics, Africa, India, and islands in the Indian Ocean. Sixteen species are known from Bolivia, several of which are widespread in the Neotropics; one species, Anemia myriophylla, is endemic to Bolivia. Hybridization is likely when species co-occur.

Prodromus of a fern flora for Bolivia. XII. Lygodiaceae

We provide a synopsis to the leptosporangiate fern family Lygodiaceae in Bolivia, comprising two species in the genus Lygodium, both of which are widely distributed in the Neotropics.

Studies on Oogenesis of the FernLygodium japonicum

Oogenesis of Lygodium japonicum (Thunb.) Sw. is studied using TEM and cytochemical techniques. The early development of the archegonia of L. japonicum is similar to those of the core-leptosporangiate ferns. A mature archegonium always contains an egg, a ventral canal cell (VCC) and a binuclear neck canal cell (NCC). With the development of the egg, a separation cavity forms between the egg and the VCC. However, a pore region, with a diameter of about 3.5 μm, constantly connects the egg and the VCC. The canal cells degenerate gradually accompanied by the accumulation of mucilaginous secretions around the canal cells. PAS reaction reveals that these secretions are polysaccharide in nature. Later development of the archegonia of L. japonicum differs greatly from the core-leptosporangiate ferns. The egg nucleus becomes highly irregular and two types of nuclear evaginations are formed during oogenesis. When the egg matures, no egg envelope or fertilization pore are formed. Only a layer of amorphous material is deposited on the outer surface of the egg. This is the first observation of a fern species that has a pore region but does not result in the formation of a fertilization pore. The pore region appears to determine the formation of the fertilization pore. These observations are consistent with the hypothesized phylogenetic position of L. japonicum relative to the core leptosporangiate ferns.

An exquisitely preserved filmy fern (Hymenophyllaceae) from the Early Cretaceous of Mongolia.

Hymenophyllaceae ("filmy ferns") are a widely distributed group of predominantly tropical, epiphytic ferns that also include some temperate and terrestrial species. Hymenophyllaceae are one of the earliest-diverging lineages within leptosporangiate ferns, but their fossil record is sparse, most likely because of their low fossilization potential and commonly poor preservation of their delicate, membranaceous fronds. A new species of unequivocal fossil Hymenophyllaceae, Hymenophyllum iwatsukii sp. nov., is described from the Early Cretaceous of Mongolia based on abundant and exceptionally well-preserved material. Bulk lignite samples collected from Tevshiin Govi and Tugrug localities in Mongolia, were disaggregated in water, cleaned with hydrochloric and hydrofluoric acids, washed, and dried in air. Fossils were examined and compared to material of extant Hymenophyllaceae using LM and SEM. The fossil fern specimens are assigned to the Hymenophyllaceae based on their membranaceous laminae with marginal sori that have sessile to short-stalked sporangia with oblique, complete annuli, and trilete, tetrahedral-globose spores. Within the family, the fossil material is assigned to the extant genus Hymenophyllum on the basis of bivalvate indusia and short, included receptacles. Hymenophyllum iwatsukii was likely an epiphyte based on the sedimentary environment in which the fossils are preserved, the associated fossil flora, and the growth habit of extant species of Hymenophyllum. The new fossil species underlines the extent to which morphological characters in Hymenophyllum have been conserved despite significant tectonic, climatic, ecological, and floristic changes since the Early Cretaceous.

The fossil Osmundales (Royal Ferns)-a phylogenetic network analysis, revised taxonomy, and evolutionary classification of anatomically preserved trunks and rhizomes.

The Osmundales (Royal Fern order) originated in the late Paleozoic and is the most ancient surviving lineage of leptosporangiate ferns. In contrast to its low diversity today (less than 20 species in six genera), it has the richest fossil record of any extant group of ferns. The structurally preserved trunks and rhizomes alone are referable to more than 100 fossil species that are classified in up to 20 genera, four subfamilies, and two families. This diverse fossil record constitutes an exceptional source of information on the evolutionary history of the group from the Permian to the present. However, inconsistent terminology, varying formats of description, and the general lack of a uniform taxonomic concept renders this wealth of information poorly accessible. To this end, we provide a comprehensive review of the diversity of structural features of osmundalean axes under a standardized, descriptive terminology. A novel morphological character matrix with 45 anatomical characters scored for 15 extant species and for 114 fossil operational units (species or specimens) is analysed using networks in order to establish systematic relationships among fossil and extant Osmundales rooted in axis anatomy. The results lead us to propose an evolutionary classification for fossil Osmundales and a revised, standardized taxonomy for all taxa down to the rank of (sub)genus. We introduce several nomenclatural novelties: (1) a new subfamily Itopsidemoideae (Guaireaceae) is established to contain Itopsidema, Donwelliacaulis, and Tiania; (2) the thamnopteroid genera Zalesskya, Iegosigopteris, and Petcheropteris are all considered synonymous with Thamnopteris; (3) 12 species of Millerocaulis and Ashicaulis are assigned to modern genera (tribe Osmundeae); (4) the hitherto enigmatic Aurealcaulis is identified as an extinct subgenus of Plenasium; and (5) the poorly known Osmundites tuhajkulensis is assigned to Millerocaulis. In addition, we consider Millerocaulis stipabonettiorum a possible member of Palaeosmunda and Millerocaulis estipularis as probably constituting the earliest representative of the (Todea-)Leptopteris lineage (subtribe Todeinae) of modern Osmundoideae.

Anatomically preserved "strobili" and leaves from the Permian of China (Dorsalistachyaceae, fam. nov.) broaden knowledge of Noeggerathiales and constrain their possible taxonomic affinities.

Noeggerathiales are an extinct group of heterosporous shrubs and trees that were widespread and diverse during the Pennsylvanian-Permian Epochs (323-252 Ma) but are of controversial taxonomic affinity. Groups proposed as close relatives include leptosporangiate ferns, sphenopsids, progymnosperms, or the extant eusporangiate fern Tmesipteris. Previously identified noeggerathialeans lacked anatomical preservation, limiting taxonomic comparisons to their external morphology and spore structure. We here document from the upper Permian of China the first anatomically preserved noeggerathialeans, which enhance the perceived distinctiveness of the group and better indicate its systematic affinity. We describe in detail the newly discovered, anatomically preserved heterosporous strobilus Dorsalistachya quadrisegmentorum, gen. et sp. nov., and redescribe its suspected foliar correlate, the pinnate leaf Plagiozamites oblongifolius. Plagiozamites possesses an omega (Ω)-shaped vascular trace and prominent cortical secretory cavities-a distinctive anatomical organization that is echoed in the newly discovered strobili. Dorsalistachya strobili bear highly dissected sporophylls alternately in two vertical rows, suggesting that they are homologs of leaf pinnae. If so, the "strobilus" is strictly a pseudostrobilus and consists of sporangium-bearing units that are one hierarchical level below true sporophylls. The "sporophylls" bear four microsporangia on the lower (abaxial) surface, occasionally interspersed with short longitudinal rows of megasporangia. A single functional megaspore develops within each winged megasporangium, suggesting adaptation for dispersal as a single unit. Dorsalistachya presents a unique combination of reproductive features that amply justifies establishment of a new family, Dorsalistachyaceae. Noeggerathiales represent a distinct taxonomic Order of free-sporing plants that most resembles early-divergent eusporangiate ferns and the more derived among the extinct progymnosperms. By the early Permian, noeggerathialeans had attained levels of reproductive sophistication similar to the most derived among the Paleozoic sphenophytes and lycophytes, but their heterosporous life history may have contributed to their extinction during the Triassic climatic aridification.

Phylogeny of the fern subfamily Pteridoideae (Pteridaceae; Pteridophyta), with the description of a new genus: Gastoniella

As the second most genera-rich fern family, Pteridaceae contain more than 1000 species contributing to ca. 10% of extant leptosporangiate fern diversity. The subfamily Pteridoideae is one of the five subfamilies often recognized. The circumscription of Pteridoideae has not been clear. A large number of species have not yet been included in any molecular analyses before. In this study, DNA sequences of six plastid loci of 154 accessions representing ca. 87 species in 14 genera of Pteridaceae subfam. Pteridoideae and four accessions representing two species in subfam. Parkerioideae and one species of subfam. Adiantoideae as outgroups were used to infer a phylogeny using maximum likelihood and maximum parsimony. Our analyses show that (1) Pteridoideae is monophyletic and the newly defined subfamily is composed of 14 genera including a newly described genus; (2) Pteridoideae is resolved into four strongly supported monophyletic clades: the Pteris clade, the Actiniopteris+Onychium clade, the JAPSTT clade, and the GAPCC clade, these being supported by not only molecular data but also morphological features and distribution information; (3) Onychium is confirmed as monophyletic and accessions of Onychium are resolved into two strongly supported clades, the O. cryptogrammoides clade and the O. siliculosum clade; and (4) Accessions of the traditionally defined Anogramma are resolved as paraphyletic in relation to Cerosora, Cosentinica, and Pityrogramma. Three species traditionally treated in Anogramma are in fact more closely related to Cerosora and Pityrogramma than they are to Anogramma. Gastoniella Li Bing Zhang & Liang Zhang, gen. nov. is described to accommodate these species and three new combinations are provided. Three currently known species of Gastoniella are distributed in the Ascension Island in South Atlantic Ocean, central Mexico, and tropical America, respectively. The new genus is distinct from Anogramma s.s. in having ultimate segments linear not obviously broadening toward the upper portion.

Molecular phylogeny of the fern family Blechnaceae (Polypodiales) with a revised genus-level treatment.

Blechnaceae, a leptosporangiate fern family nested within eupolypods II, comprises 200-250 species, typically divided among seven to nine genera. Despite recent molecular studies of the family, it still lacks a modern taxonomic update based on broad sampling from the two centres of diversity-the Neotropics and Australasia/Oceania. To test generic circumscriptions, we have assembled the broadest dataset thus far, from three plastid regions (rbcL, rps4-trnS, trnL-trnF) and with taxonomic sampling focused on both major diversity centres. Our sampling includes 156 taxa and 178 newly generated sequences. We recognize three subfamilies, each corresponding to a highly supported clade across all analyses (maximum parsimony, Bayesian inference and maximum likelihood). The genera Salpichlaena, Stenochlaena and Telmatoblechnum are monophyletic, while Blechnum is polyphyletic, because Brainea, Doodia and Sadleria all nest within it. We outline and explain a plan to resolve the polyphyly of Blechnum by recognizing additional, monophyletic, segregate genera.