Toward a new circumscription of the twinsorus‐fern genus Diplazium (Athyriaceae): A molecular phylogeny with morphological implications and infrageneric taxonomy

Abstract

Diplazium and allied segregates (Allantodia, Callipteris, Monomelangium) represent highly diverse genera belonging to the lady‐fern family Athyriaceae. Because of the morphological diversity and lack of molecular phylogenetic analyses of this group of ferns, generic circumscription and infrageneric relationships within it are poorly understood. In the present study, the phylogenetic relationships of these genera were investigated using a comprehensive taxonomic sampling including 89 species representing all formerly accepted segregates. For each species, we sampled over 6000 DNA nucleotides of up to seven plastid genomic regions: atpA, atpB, matK, rbcL, rps4, rps4‐trnS IGS, and trnL intron plus trnL‐trnF IGS. Phylogenetic analyses including maximum parsimony, maximum likelihood and Bayesian methods congruently resolved Allantodia, Callipteris and Monomelangium nested within Diplazium; therefore a large genus concept of Diplazium is accepted to keep this group of ferns monophyletic and to avoid paraphyletic or polyphyletic taxa. Four well‐supported clades and eight robust subclades were found in the phylogenetic topology. Reconstruction of the evolutionary pattern of morphological characters, such as dissections of leaves, petiole/rachis scales, and shapes of sori, recovered some character combinations of systematic value for infrageneric classification. In light of morphological characters and our molecular phylogeny, a re‐defined Diplazium and an infrageneric classification are proposed.

Rediscovery ofCystoathyrium chinenseChing (Cystopteridaceae): Phylogenetic placement of the critically endangered fern species endemic to China

“…Moreover, its close relationship to the Cystopteris bulbifera clade (MP‐BS = 82%, ML‐BS = 95%, and BI‐PP = 1.00) appears to be further supported by similar leaf shapes and glands appearing on the blades (Haufler et al, ; Wang et al, ). In addition, our results further indicate that some morphological characters are perhaps better treated as continuous variation and therefore are not suitable to be diagnostic characters (Wei et al, , ; Rothfels et al, ; Sundue & Rothfels, ). For example, emphasizing morphologies of rhizomes, scales, and leaf dissection may suggest a closer relationship between Cystoathyrium and Athyrium (Ching, ; Pichi‐Sermolli, ; Kramer et al, ; Wang, , ; Wang et al, ) than is supported by our study.…”

“…Eupolypods II, representing one of the largest fern lineages, has been well circumscribed by recent molecular phylogenetic and revisionary studies (Schuettpelz & Pryer, ; Rothfels et al, , ). Meanwhile, circumscriptions of many puzzling genera residing in it are becoming clearer (e.g., Acystopteris , Cystopteris , and Gymnocarpium , Rothfels et al, ; Allantodia , Callipteris , and Monomelangium , Wei et al, ; Diellia , Schneider et al, ; Diplaziopsis and Homalosorus , Wei et al, ; Li et al, ; Hemidictyum , Schuettpelz & Pryer, ; Kuo et al, ; Rhachidosorus , Rothfels et al, ). The monophyly of Cystopteridaceae was supported, but it was not supported as having a close relationship with Athyriaceae (Kuo et al, ; Rothfels et al, , ).…”

Embracing the pteridophyte classification of Ren‐Chang Ching using a generic phylogeny of Chinese ferns and lycophytes

“…Cyclosorus , Davallia, Diplazium , and Lepisorus are further examples of genera that underwent substantial changes in their circumscription as the result of the improved understanding of the phylogenetic relationships of these ferns (Sano et al, ; Smith et al, ; Tsutsumi et al, ; Wang et al, ; He & Zhang, ; Liu & Schneider, ; Wei et al, ). However, the newly obtained insights into the phylogeny of ferns may not always correspond to the establishment of broadly defined taxa but may also result in the acceptance of smaller, biologically meaningful taxa as illustrated in the studies on the polygrammoid genus Grammitis (detailed discussion below).…”

Foliar epidermal micromorphology and its taxonomic implications in some selected species of Athyriaceae

“…Athyriaceae a leptosporangiate fern family comprises 3 genera and 650 species worldwide in which two genera Athyrium and Diplazium contributed nearly 85% species and third genus is Deparia estimated to contain 15% species (Schneider et al, ; Wei et al, ). The family is characterized by: creeping rhizomes, ascending, or erect, scales at apices; these usually noncalthrate, glabrous, glandular, or ciliate, petioles with two elongate or crescent‐shaped vascular bundles facing one another, blades monomorphic; rarely dimorphic, veins pinnate or forking; free, sori abaxial; round J‐shaped, or linear with reinform, monolete, perine winged, ridged or spiny (Smith et al, ).…”

“…The family is characterized by: creeping rhizomes, ascending, or erect, scales at apices; these usually noncalthrate, glabrous, glandular, or ciliate, petioles with two elongate or crescent‐shaped vascular bundles facing one another, blades monomorphic; rarely dimorphic, veins pinnate or forking; free, sori abaxial; round J‐shaped, or linear with reinform, monolete, perine winged, ridged or spiny (Smith et al, ). The family has been variously circumscribed and its limits are still uncertain (Hasebe et al, ; Liu, Chiou, & Kato, ; Wang, Chen, Zhang, Lu, & Zhao, ; Wei, Schneider, & Zhang, ). In Pakistan, the family is represented by 23 species belonging to 3 genera and it is commonly distributed in Himalayan and Northern region of Pakistan (Nakaike & Malik, ; Stewart, ; Stewart, Ali, & Nasir, ).…”