Molecular phylogenetic analyses reveal a close relationship between powdery mildew fungi on some tropical trees and Erysiphe alphitoides, an oak powdery mildew

To investigate the phylogenetic relationships among the powdery mildew fungi of some economically important tropical trees belonging to Oidium subgenus Pseudoidium, we conducted molecular phylogenetic analyses using 30 DNA sequences of the rDNA internal transcribed spacer (ITS) regions and 26 sequences of the domains D1 and D2 of the 28S rDNA obtained from the powdery mildews on Hevea brasiliensis (para rubber tree), Anacardium occidentale (cashew), Bixa orellana, Citrus spp., Mangifera indica (mango), and Acacia spp. The results indicate that the powdery mildew fungi isolated from these tropical trees are closely related to one another. These powdery mildews are also closely related to E. alphitoides (including Erysiphe sp. on Quercus phillyraeoides). Because of the obligate biotrophic nature of the powdery mildew fungi, the relationship between powdery mildews and their host plants is conservative. However, the present study suggests that a particular powdery mildew species has expanded its host ranges on a wide range of the tropical trees. This article also suggests that a powdery mildew fungus distributed in temperate regions of the Northern Hemisphere expanded its host ranges onto tropical plants and may be a good example of how geographical and host range expansion has occurred in the Erysiphales.     

Phylogenetic relationships of Nemania plumbea sp. nov. and related taxa based on ribosomal ITS and RPB2 sequences

During a survey fungal diversity of xylariaceous fungi in Thailand, a new Nemania species, N. plumbea, was identified. Nemania plumbea is characterized by soft-textured grey stromata on a persistent mat of white hyphae, pale brown ascospores with a short germ-slit on the more convex side. It also produces a Geniculosporium-like anamorph in culture. In order to evaluate its phylogenetic relationships among related species and genera, ITS-5.8S rDNA and RPB2 were analysed separately and simultaneously. Results from the phylogenetic analyses indicate that there is close phylogenetic association between N. plumbea and N. aenea. A preliminary account into the natural grouping of Xylariaceae based on ITS-5.8S rDNA and RPB2 sequences is also discussed.     

Tilletiopsis derxii, Tilletiopsis oryzicola and Tilletiopsis penniseti, three new species of the ustilagionomycetous anamorphic genus Tilletiopsis isolated from leaves in Thailand

Four strains of ballistoconidium-forming yeast-like fungi (K-95, K-125, K-132 and K139), isolated from plants collected in Bangkok, Thailand, were assigned to the genus Tilletiopsis based on morphological and chemotaxonomical characteristics. On the basis of sequence data of 18S rDNA and the D1/D2 region of 26S rDNA, strains K-95, K-125 and K-132 were close to T. flava and T. fulvescens, and strain K-139 each formed related to T. minor. DNA-DNA reassociation experiments with related species revealed that strains K-125, K-132 and K-139 each formed a new and distinct species whereas strain K-95 was identified as T. flava. Tilletiopsis derxii Takashima et Nakase sp. nov. (JCM 10217^T; K-125), Tilletiopsis oryzicola Takashima et Nakase sp. nov. (JCM 10218^T; K-132), and Tilletiopsis penniseti Takashima et Nakase sp. nov. (JCM 10216^T; K-139) are the names proposed for the new taxa.     

Phylogeny and taxonomy of the Asian grapevine leaf rust fungus, <Emphasis Type="Italic">Phakopsora euvitis</Emphasis>, and its allies (Uredinales)

Heteroecious Phakopsora euvitis, P. vitis, and P. ampelopsidis, autoecious P. meliosmae, and an unconnected Aecidium on Meliosma are closely allied. A total of 45 collections representing the five rust fungi from Japan, Australia, and East Timor were subjected to molecular phylogenetic analyses: the D1/D2 region of nuclear large subunit rDNA and nuclear small subunit internal transcribed spacer 2 (ITS2) region including 5.8S rDNA were analyzed. Tree topologies generated from parsimony and distance methods of the D1/D2 and ITS2 sequences were similar. The 45 collections (44 for ITS2 and 33 for D1/D2, with 32 common for both analyses) are grouped into seven clades: P. ampelopsidis, P. vitis, unconnected Aecidium, P. euvitis from Japan, P. euvitis from Australia and East Timor, P. meliosmae on M. myriantha, and P. meliosmae on M. tenuis. The results confirm the phylogenetic distinctness of P. euvitis, P. ampelopsidis, and P. vitis distributed in Japan. A grapevine leaf rust fungus in Australia and East Timor has genetically diverged from P. euvitis in Japan. The unconnected Aecidium is highly likely to be an aecial anamorph of a Phakopsora fungus. Autoecious Phakopsora fungi on M. meliosmae and M. tenuis need further host-specificity and morphological studies to confirm their taxonomic status.     

基于可培养方法分析云南腾冲小空山火山谷芽胞杆菌分布特征

【目的】为了解云南腾冲小空山火山谷土壤中可培养芽胞杆菌种类分布特征。【方法】采用可培养手段对小空山火山谷阳坡、谷底和阴坡土壤中的芽胞杆菌进行分离培养,根据16S rRNA基因序列同源性对分离菌株进行鉴定,并分析系统发育地位。利用Canoco5软件分析采样点芽胞杆菌种类分布特征与土壤样品理化性质的相关性。【结果】从火山谷土壤样品中共分离获得180株芽胞杆菌,16S rRNA基因测序鉴定结果表明分离菌株隶属于芽胞杆菌纲2个科(芽胞杆菌科和类芽胞杆菌科)、6个属、34个种,其中芽胞杆菌属(Bacillus) 11个种,类芽胞杆菌属(Paenibacillus) 14个种,短芽胞杆菌属(Brevibacillus)3个种,赖氨酸芽胞杆菌属(Lysinibacillus)4个种,嗜冷芽胞杆菌属(Psychrobacillus)1个种和绿芽胞杆菌属(Viridibacillus)2个种,其中7个菌株与其最近模式菌株16SrRNA相似性低于种的界定阈值(98.65%),为芽胞杆菌潜在新物种。优势属为芽胞杆菌属和类芽胞杆菌属,优势种为蕈状芽胞杆菌(Bacillusmycoides),图瓦永芽胞杆菌(Bacillustoyonensis),蜡状芽胞杆菌(Bacilluscereus),解木糖赖氨酸芽胞杆菌(Lysinibacillusxylanilyticus),蜂房类芽胞杆菌(Paenibacillusalvei)和沙地绿芽胞杆菌(Viridibacillus arenosi)。其中16个种分离自阳坡,29个种分离自阴坡,9个种分离自谷底,三者共同种类为6种。阳坡、谷底和阴坡的芽胞杆菌种群分布Bray-Curtis相似性为62.4%,多样性分析结果表明,Shannon指数(H′)大小次序为阴坡阳坡谷底。环境因子分析发现,芽胞杆菌种群分布多样性特征与其土壤的海拔高度、碳氮比和硫含量呈负相关,而和碳源和氮源含量呈正相关。【结论】从以上结果得出,云南腾冲火山谷有着较为丰富的芽胞杆菌资源,且还存在可分离培养的芽胞杆菌的潜在新物种,为利用火山微生物资源提供了保障。     

Phylogenetic investigations of Sordariaceae based on multiple gene sequences and morphology

The family Sordariaceae incorporates a number of fungi that are excellent model organisms for various biological, biochemical, ecological, genetic and evolutionary studies. To determine the evolutionary relationships within this group and their respective phylogenetic placements, multiple-gene sequences (partial nuclear 28S ribosomal DNA, nuclear ITS ribosomal DNA and partial nuclear β-tubulin) were analysed using maximum parsimony and Bayesian analyses. Analyses of different gene datasets were performed individually and then combined to generate phylogenies. We report that Sordariaceae, with the exclusion Apodus and Diplogelasinospora, is a monophyletic group. Apodus and Diplogelasinospora are related to Lasiosphaeriaceae. Multiple gene analyses suggest that the spore sheath is not a phylogenetically significant character to segregate Asordaria from Sordaria. Smooth-spored Sordaria species (including so-called Asordaria species) constitute a natural group. Asordaria is therefore congeneric with Sordaria. Anixiella species nested among Gelasinospora species, providing further evidence that non-ostiolate ascomata have evolved from ostiolate ascomata on several independent occasions. This study agrees with previous studies that show heterothallic Neurospora species to be monophyletic, but that homothallic ones may have a multiple origins. Although Gelasinospora and Neurospora are closely related and not resolved as monophyletic groups, there is insufficient evidence to place currently accepted Gelasinospora and Neurospora species into the same genus.     

Bambusicolous fungi in Japan (6): Katumotoa, a new genus of phaeosphaeriaceous ascomycetes

A new genus, Katumotoa, is established for a single species, K. bambusicola, collected from culms of Sasa kurilensis. Morphological differences between Katumotoa and some related genera are noted. Katumotoa is characterized by perithecioid ascomata, thin ascomal wall composed of small pseudoparenchymatous cells, cellular pseudoparaphyses, fissitunicate asci, and apiosporous fusiform ascospores with bipolar mucilaginous sheath. From these features, it is considered that the genus belongs to Phaeosphaeriaceae in Pleosporales.     

On the conspecificity ofAnopheles fluviatilis species S withAnopheles minimus species C

Anopheles fluviatilis andAn. minimus complexes, each comprising of at least three sibling species, are closely related and important malaria vectors in Oriental Region. RecentlyAn. fluviatilis species S, which is a highly efficient malaria vector in India, has been made conspecific withAn. minimus species C (senior synonym) on the basis of homology in 335 base pair nucleotide sequence of D3 domain of 28S ribosomal DNA(rDNA). We examined the conspecificity of these two nominal species by obtaining and analysing the DNA sequences of nuclear ribosomal loci internal transcribed spacer 2 (ITS2) and D2-D3 domain of 28S rDNA (28S-D2/D3) from those ofAn. fluviatilis S andAn. minimus C. We found that the sequences ofAn. fluviatilis S are appreciably different from those ofAn. minimus C with pair-wise distance (Kimura-2-parametre model) of 3.6 and 0.7% for loci ITS2 and 28S-D2/D3, respectively. Pair-wise distance and phylogenetic analyses using ITS2 sequences of members of Minimus and Fluviatilis Complexes revealedthat An. fluviatilis S is distantly related toAn. minimus C as compared to any other members of the Fluviatilis Complex. These findings suggest that the two nominal species,An. fluviatilis S andAn. minimus C, do not merit synonymy. The study also confirms that the reported speciesAn. fluviatilis X is synonym with species S.     

Cryptococcus haglerorum,sp. nov., an anamorphic basidiomycetous yeast isolated from nests of the leaf-cutting ant Atta sexdens

A yeast strain (CBS 8902) was isolated from the nest of a leaf-cutting ant and was shown to be related to Cryptococcus humicola. Sequencing of the D1/D2 region of the 26S ribosomal DNA and physiological characterization revealed a separate taxonomic position. A novel species named Cryptococcus haglerorum is proposed to accommodate strain CBS 8902 that assimilates n-hexadecane and several benzene compounds. Physiological characteristics distinguishing the novel species from some other members of the C. humicola complex are presented. The phylogenetic relationship of these strains to species of the genus Trichosporon Behrend is discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

New fungal genera, Tectonidula gen. nov. for Calosphaeria-like fungi with holoblastic-denticulate conidiogenesis and Natantiella gen. nov. for three species segregated from Ceratostomella

Two morphologically similar groups of ascomycetes with globose to subglobose perithecia, elongate necks, unitunicate asci floating freely at maturity, and hyaline ascospores currently placed in Calosphaeria s. lat. and Ceratostomella s. lat., respectively, are studied. The Calosphaeria-like fungi have groups of perithecia growing between cortex and wood, arranged in circular groups with converging necks and piercing the cortex in a common point; the asci with a shallow apical ring and U- to horseshoe-shaped hyaline ascospores are compared with Calosphaeria pulchella, the type species of the genus. Conidiogenesis of the investigated Calosphaeria-like fungi is holoblastic-denticulate; ramichloridium-like and sporothrix-like conidiophores and conidia were formed in vitro. Ascospore and ascus morphology, structure of the ascal apex, ascogenous system, mode of conidiogenesis and the large subunit rRNA sequences of this group differ considerably from C. pulchella and both groups are unrelated. Thus a new genus, Tectonidula, is described with two accepted species, T. hippocrepida and T. fagi; they are separated by ascospore and ascus morphology and holoblastic-denticulate conidiogenesis from the core species of Calosphaeria. The placement of Tectonidula among perithecial ascomycetes is discussed. The relationship of Tectonidula with Barbatosphaeria and two ramichloridium-like hyphomycetous genera Rhodoveronaea and Myrmecridium is investigated. Three species formerly attributed to Ceratostomella are studied. The revision of the herbarium type specimen and fresh material of Ceratostomella ligneola revealed that it is conspecific with Ceratostomella ampullasca and Ceratostomella similis. The LSU phylogeny clearly separated C. ligneola from Ceratostomella s. str. and morphologically similar Lentomitella. On the basis of molecular sequence data and detailed comparison of morphology of asci, ascospores and ascogenous system the genus Natantiella is described for C. ligneola with C. ampullasca and C. similis as its synonyms. Natantiella produced sterile mycelium in vitro.     

Dinoflagellate community analysis of a fish kill using denaturing gradient gel electrophoresis

A molecular method using the polymerase chain reaction (PCR) amplification of small subunit gene sequences (18S rDNA) and denaturing gradient gel electrophoresis (DGGE) was used to determine both the population complexity and species identification of organisms in harmful algal blooms. Eighteen laboratory cultures of dinoflagellates, including Akashiwo, Gymnodinium, Heterocapsa, Karenia, Karlodinium, Pfiesteria, and Pfiesteria-like species were analyzed using dinoflagellate-specific oligonucleotide primers and DGGE. The method is sensitive and able to determine the number of species in a sample, as well as the taxonomic identity of each species, and is particularly useful in detecting differences between species of the same genus, as well as differences between morphologically similar species. Using this method, each of eight Pfiesteria-like species was verified as being clonal isolates of Pfiesteria piscicida. The sensitivity of dinoflagellate DGGE is approximately 1000 cells/ml, which is 100-fold less sensitive than real-time PCR. However, the advantage of DGGE lies in its ability to analyze dinoflagellate community structure without needing to know what is there, while real-time PCR provides much higher sensitivity and detection levels, if probes exist for the species of interest, attributes that complement DGGE analysis. In a blinded test, dinoflagellate DGGE was used to analyze two environmental fish kill samples whose species composition had been previously determined by other analyses. DGGE correctly identified the dominant species in these samples as Karlodinium micrum and Heterocapsa rotundata, proving the efficacy of this method on environmental samples. Toxin analysis of a clonal isolate obtained from the fish kill samples confirmed the presence of KmTx2, corroborating the earlier genetic identification of toxic K. micrum in the fish kill water sample.     

Production of monoclonal antibodies against surface antigens of spores from arbuscular mycorrhizal fungi by an improved immunization and screening procedure

Monoclonal antibodies (mAbs) were produced against surface antigens of chlamydospores of arbuscular mycorrhizal (AM) fungi by immunizing mice with crushed or complete spores. The intrasplenic approach proved to be superior to the intraperitoneal method of immunization with regard to the amount of antigen required for the immune response. The hybridoma technology was combined with an improved screening procedure, applying an immunogold-silver staining technique to semi-thin sections of spores. In this way, mAbs to surface antigens on the outer wall could be selected. Two mAbs were raised against Glomus etunicatum and G. scintillans spores. Cross-reactivities of the antibodies to other structures of the fungus, to other species of Glomus and to other soil-borne fungi were tested with indirect immunofluorescent labelling. The mAbs did not react with non-AM fungi. One mAb (A5B1) selectively recognized G. etunicatum, another (D12F11) exhibited limited interspecies cross-reactivities. One further mAb (H8F7), which reacted with spores of all AM fungi but not with other fungi, was shown to be specific for Bacillus mycoides. The implications are discussed.     

Teleomorph-anamorph relationships and reclassification of <Emphasis Type="Italic">Cordyceps cuboidea</Emphasis> and its allied species

Based on morphological characteristics and molecular phylogeny, we reclassified Cordyceps cuboidea and allied species C. alboperitheciata, C. prolifica, and Ophiocordyceps ryogamiensis. We investigated their teleomorph-anamorph relationships and revealed that these four species have Hirsutella-like anamorphs with morphological differences between them. By analyzing their molecular phylogeny, inferred from DNA sequences of internal transcribed spacer (ITS) and large subunit (LSU) D1/D2 region of rDNA, they were separated into four close-knit clades. Although C. prolifica and O. ryogamiensis formed their own clades, isolates of C. cuboidea separated into two clades, i.e., a true C. cuboidea clade and one resembling a new species, the O. paracuboidea clade. The latter two species are distinguished by the fruiting region of the stroma. In addition, C. alboperitheciata is regarded as a synonym of C. cuboidea. From the morphology, teleomorph-anamorph relationships, and molecular phylogeny, we concluded these species should be assigned to the genus Ophiocordyceps.     

Meira nashicola sp. nov., a novel basidiomycetous, anamorphic yeastlike fungus isolated from Japanese pear fruit with reddish stain

Three undescribed strains of basidiomycetous, anamorphic yeastlike fungi were isolated from Japanese pear fruits with a reddish stain collected in Tottori Prefecture, Japan. The strains are classified in a single group and assigned to the genus Meira by conventional and chemotaxonomic studies. Sequence analyses of the D1/D2 domain of 26S rDNA and internal transcribed spacer (ITS) regions indicate that the strains represent a novel species with a close phylogenetic relationship to Meira geulakonigii and M. argovae. The name Meira nashicola sp. nov. is proposed for the strains (type strain PFS 002 = MAFF 230028 = CBS 117161).     

养猪微生物发酵床芽胞杆菌空间分布多样性

了解微生物发酵床大栏养猪垫料中的芽胞杆菌多样性和空间分布规律,为微生物发酵床管理、芽胞杆菌新资源挖掘及菌剂开发奠定基础。将发酵床划分为32个方格(4行×8列),采用五点取样法获得每个方格的样品。采用可培养法从32份样品中分离芽胞杆菌菌株,利用16S rRNA基因序列初步鉴定所分离获得的芽胞杆菌种类。利用聚集度指标和回归分析法,分析芽胞杆菌的样方空间分布型。通过Shannon-Wiener多样性指数、Simpson优势度指数、Hill指数及丰富度指数分析,揭示微生物发酵床中芽胞杆菌的空间分布多样性。从32份样品中共获得芽胞杆菌452株,16S rRNA基因鉴定结果表明它们分别隶属于芽胞杆菌纲的2个科、8个属、48个种。其中,种类最多的为芽胞杆菌属(Bacillus),30种;赖氨酸芽胞杆菌属(Lysinibacillus),6种;类芽胞杆菌属(Paenibacillus),5种;短芽胞杆菌属(Brevibacillus),3种;鸟氨酸芽胞杆菌属(Ornithinibacillus)、大洋芽胞杆菌属(Oceanibacillus)、少盐芽胞杆菌属(Paucisalibacillus)和纤细芽胞杆菌属(Gracilibacillus)各1个种。芽胞杆菌种类在发酵床空间分布差异很大,根据其空间出现频次,可分为广分布种类,如地衣芽胞杆菌(Bacillus licheniformis);寡分布种类,如根际芽胞杆菌(B.rhizosphaerae);少分布种类,如弯曲芽胞杆菌(B.flexus)。依据其数量,可分为高含量组优势种群,如地衣芽胞杆菌(B.licheniformis);中含量组常见种群,耐盐赖氨酸芽胞杆菌(Lysinibacillus halotolerans);寡含量组寡见种群,如根际芽胞杆菌(B.rhizosphaerae);低含量组偶见种群,如土地芽胞杆菌(B.humi)。空间分布型聚集度和回归分析测定表明,芽胞杆菌在微生物发酵床的分布类型为聚集分布。微生物发酵床垫料中芽胞杆菌种类总含量高达4.41×108个/g,其种类含量范围为0.01—94.1×106个/g(均值为8.96×106个/g),丰富度指数(D)、优势度指数(λ)、Shannon-Wiener指数(H')和均匀度指数(J')分别为0.4928、0.2634、1.3589和0.9803,其中香农指数最大的单个芽胞杆菌种类为地衣芽胞杆菌(B.licheniformis)。根据芽胞杆菌种类多样性指数聚类分析,当欧式距离λ=17时,可分为高丰富度高含量和低丰富度低含量类型。微生物发酵床的芽胞杆菌种类丰富、数量高,是一个天然的菌剂"发酵罐",有望直接作为微生物菌剂,应用于土壤改良、作物病害防控、污染治理等领域。     

An aero-aquatic fungus, <Emphasis Type="Italic">Peyronelina glomerulata</Emphasis>, is shown to have teleomorphic affinities with cyphelloid basidiomycetes

On decayed wood near a stream, tiny cyphelloid, hair-bearing, Flagelloscypha-like basidiomata were found coexisting with conidia of an aero-aquatic fungus, Peyronelina glomerulata. An isolate originating from the basidioma produced conidia of P. glomerulata by soaking the culture in water. Three additional strains originating from conidia of P. glomerulata produced immature basidiomata with basidium-like structures on the agar medium after about 4 months incubation. Fine structure of the hyphal septa of P. glomerulata was found to be of the dolipore type. Phylogenetic analysis based on sequences from the D1/D2 regions of the LSU rDNA showed that the strains from conidia and from a basidioma clustered together in the Flagelloscypha clade and nested within the Nia clade of Hymenomycetes. The culture studies and molecular phylogenetic analysis suggested that P. glomerulata has a Flagelloscypha teleomorph, a cyphelloid basidiomycete. The molecular data also indicate that P. glomerulata is phylogenetically related to the marine basidiomycetes, Nia and Halocyphina. Thus, this study revealed that cyphelloid basidiomycetes have evolved into both marine as well as freshwater habitats by morphological adaptations of the teleomorphs in the former and of the anamorph in the latter case.     

Community analysis of arbuscular mycorrhizal fungi in a warm-temperate deciduous broad-leaved forest and introduction of the fungal community into the seedlings of indigenous woody plants

A community of arbuscular mycorrhizal (AM) fungi was investigated in a warm-temperate deciduous broad-leaved forest using a molecular analysis method. Root samples were obtained from the forest, and DNA was extracted from the samples. Partial 18S rDNA of AM fungi were amplified from the extracted DNA by polymerase chain reaction using a universal eukaryotic primer NS31 and an AM fungal-specific primer AM1. After cloning the PCR products, 394 clones were obtained in total, which were divided into five types by restriction fragment length polymorphism (RFLP) with HinfI, RsaI, and Hsp92II. More than 20% of the clones were randomly selected from each RFLP type and sequenced. Phylogenetic analysis showed that all the obtained clones belonged to Glomus but could not be identified at species level. Topsoil of the forest containing plant roots was inoculated to nonmycorrhizal seedlings of indigenous woody plants, Rhus javanica var. roxburghii and Clethra barvinervis, to introduce the community of AM fungi into the seedlings. Among these five RFLP types, four types were detected from both seedlings, which indicates that the AM fungal community in the forest root samples was introduced at least partly into the seedlings. Meanwhile, an additional four types that were not found in the forest root samples were newly detected in the seedlings, these types were closely related to one another and close to G. fasciculatum or G. intraradices. It is expected that a community of indigenous diverse AM fungi could be introduced into target fields by planting these mycorrhizal seedlings.     

<Emphasis Type="Italic">Candida patagonica</Emphasis> sp. nov., a new species of yeast from cellar surfaces

A novel anamorphic yeast species belonging to the genus Candida has been isolated from cellar surfaces in North Patagonia. Morphological and physiological observation and phylogenetic analysis were performed. Pseudomycelium was plentifully produced. No sexual reproduction was observed. From sequence analysis of the 26S rDNA D1/D2 region, Candida bituminiphila and Zygoascus hellenicus were the closest species with 40 and 79 bp substitutions, respectively. C. bituminiphila differed physiologically from the novel species in its ability to assimilate sucrose and erythritol, in not fermenting any sugars, in growing without some vitamin compounds, and in growing at 40°C. All these data support the hypothesis that the new yeast, named Candida patagonica, is a novel species related to C. bituminiphila. The type strain is UNCOMA 159.5 (= CECT 12029 = CBS 10443).     

越南莲座状复苏卷柏一新种——越南卷柏(卷柏科)

该文描述了在越南发现的卷柏科一新种——越南卷柏(Selaginella pseudotamariscina X. C. Zhang & C. W. Chen)。经过分子系统发育分析并与近缘种形态比较,认为该新种是卷柏属(Selaginella)同穗亚属(subg. Stachygynandrum)的一个物种,与S. digitata-S. imbricata分支为姐妹群关系。该新种与卷柏(S. tamariscina)和垫状卷柏(S. pulvinata)的形态近似,其植株均为莲座状,但不同之处在于中叶对称,似披针形,上表面具1沟槽; 孢子叶穗略压扁; 孢子叶和营养叶性状和排列近似,孢子叶非同形,略异形,正置,腹面孢子叶大于背面孢子叶; 背面孢子叶败育,孢子囊仅见于腹面孢子叶基部。