Chromosome numbers in representative myxomycetes: a cytogenetic study

Myxomycetes are also called plasmodial slime molds, due to one of their characteristic features, the occurrence of the plasmodium. However, most of the distinguishing characters of the five orders currently recognised are based on the morphology of fruiting bodies and spores. Although a few myxomycetes have become widely used model organisms for genetic and cytological studies, complete information relating to the number of chromosomes in haploid cells (n) is lacking thus far. Only two species of the order Physarales have been examined with respect to chromosome numbers. Here, we present a complete data set on the numbers of chromosomes in ten species of myxomycetes that are members of all five orders. Our analysis indicates that n?=?21 is the evolutionary ancient chromosome number that occurs in the morphologically simple orders Liceales and Ceratiomyxales. More derived taxa, such as the Physarales, have significantly higher chromosome numbers (n?=?30). These data shed light on the phylogenetic relationships within the myxomycetes.     

Species-specific cell mobility of bacteria-feeding myxamoebae in plasmodial slime molds

On decaying wood or litter in forests, plasmodial slime molds (myxomycetes) represent a large fraction of eukaryotic protists that feed on bacteria. In his seminal book Experimental Physiology of Plants (1865), Julius Sachs referred to the multinucleate plasmodium of myxomycetes, which were considered at that time as primitive plants (or fungi). Today it is well established that myxomycetes are members of the Amoebozoa (Protista). In this study we compare the mobility of myxamoebae of 3 European species, Lycogala epidendrum (order Liceales), Tubulifera arachnoidea, and Trichia decipiens (order Trichiales). Using agar plates, on which 3 separate bacterial species were cultivated as prey organisms (Methylobacterium mesophilicum, Escherichia coli, Agrobacterium tumefaciens), we document large differences in cell motility between the myxomycetes investigated. In addition, we show that the 3 species of myxamoebae can be distinguished based on their average cell size. These data shed light on the mode of co-occurrence via differential substrate utilization in these members of the Amoebozoa.     

Association between myxomycetes and the decay stage of coarse woody debris in an evergreen broadleaf forest in warm temperate Japan

Myxomycetes inhabit coarse woody debris in varying stages of decay; however, their ecology in the dead wood of evergreen broadleaf trees is not well known. In this study, we examined the relationships between myxomycete species and the decay stage of wood from fallen trees in an evergreen broadleaf forest in Japan. Myxomycete species richness and abundance were calculated for eight stages of decay in fallen logs, according to the appearance and wood hardness of log portions. A total of 70 myxomycete species (including varieties) were found on the logs. Moderately decayed wood was the preferred habitat of myxomycetes (57 species; 81% of the total) and most species inhabited moist decayed wood. Analysis by nonmetric multidimensional scaling enabled the differentiation of myxomycete assemblages, with five groupings recognized across the progression of decay. Forty-two species preferred a particular decay stage, represented by the decay index. Physarum viride and Stemonitis splendens particularly preferred the less-decayed wood and Stemonitopsis typhina var. similis especially inhabited the well-decayed wood. Species from the order Physarales dominated the less-decayed wood, whereas Trichiales and Liceales species dominated the softer well-decayed wood. Myxomycetes diversity was high in and varied among logs with various stages of decay in a typical Japanese evergreen forest.     

鼎湖山自然保护区黏菌的物种组成和多样性

为了揭示鼎湖山自然保护区黏菌的物种组成及物种多样性在不同生境的异同,该研究选择6个不同海拔高度的样地,从中收集地面基物和树皮基物进行湿室培养,通过物种鉴定和发生数量统计分析物种的组成和多样性。结果表明:共计获得6目8科18属49种黏菌,其中绒泡菌目(Physarales)最多(17种),其次为团毛菌目15种、发网菌目(Stemonitales)11种、无丝菌目(Lieeales)4种、鹅绒菌目(Ceratiomyxales)和刺轴菌目(Eehinosteliales)分别各1种。主要优势种为灰团网菌(Arcyria cinerea)(RA=27.03%)和垫形双皮菌(Diderma effusum)(RA=21.14%)。随着海拔的升高,黏菌物种多样性逐渐降低,Shannon-Wiener多样性指数最低值出现在海拔300 m处,为1.66±0.12;而其优势集中性指数最高,为0.25±0.05。两个样地的海拔高度相距越大,共有的物种数越少相似性指数越低。雨季共获得黏菌33种,旱季共获得黏菌40种,共有种为22种,相似性系数为60.27%,旱季基物上发生的黏菌Shannon-Wiener多样性指数显著高于雨季。地面基物上的黏菌物种数为39种,高于树皮基物的26种,且两者的Shannon-Wiener多样性指数具有显著性差异,表明黏菌对地面基物的偏好性大于树皮基物。     

中国热带黏菌的已知种类

我国广东、广西、云南和台湾4省区的南部及海南、香港和澳门全境均在北回归线以南,属于地理上的热带。为了全面系统地开展我国热带地区黏菌资源的多样性和分类学研究,文中通过标本采集、鉴定和复核以及文献考证研究了已知的发生于中国热带地区的黏菌种类,对一些物种分类地位和名称变化进行了更新,同时记述了每个物种的生境和在我国热带地区的分布。结果表明:中国热带地区现知黏菌6目13科35属160种,其中,广东南部为23种,广西南部为61种,海南为33种,云南南部为67种,台湾南部为26种,香港为66种,澳门为10种。从黏菌的目级水平来看,中国热带地区现知黏菌鹅绒菌目1种,刺轴菌目5种,无丝菌目22种,团毛菌目32种,绒泡菌目73种,发网菌目27种。     

Evolution of dark-spored Myxomycetes (slime-molds): molecules versus morphology

The Myxomycetes are a major component of soil amoebae, displaying a complex life cycle that terminates in the formation of often macroscopic fruiting bodies. The classification of Myxomycetes is controversial and strongly depends on the weight given by different authors to morphological and developmental characters. We used a molecular approach to establish the phylogenetic relationships in the dark-spored orders Stemonitales and Physarales. Twenty-five small subunit ribosomal RNA gene sequences were obtained, with focus on two Stemonitales genera, Lamproderma and Comatricha. Unexpectedly, our results show that Stemonitales are paraphyletic with Physarales arising from within a Lamproderma clade. The genus Lamproderma itself is polyphyletic and can be divided into two distinct clades. Additionally, we found that Comatricha nigricapillitia comprises two cryptic species, both related to Enerthenema. Our study allows the reappraisal of morphological and developmental characters in the light of molecular data and sets foundations for a new classification of Myxomycetes.     

Geographical distribution of myxomycetes living on Cryptomeria japonica bark in Japan

There is little available data on the biogeography of myxomycetes at the regional scale within any given climate zone. To investigate the geographical distribution of these protozoans, we focused on corticolous myxomycetes associated with the bark of Cryptomeria japonica trees, which we sampled extensively throughout Japan. Myxomycete sporophores developed in 73% of 2244 moist-chamber cultures of 188 bark samples from 24 regions, including 31 species. The most abundant species were Paradiacheopsis rigida and Cribraria confusa, which accounted for over 20% of all myxomycetes sampled. Non-metric multidimensional scaling was used to analyze the distribution of myxomycetes in relation to geographical variables and bark pH. The distribution of myxomycetes was influenced by altitude, temperature and bark pH. Temperature gradients and relative abundance of species were negatively correlated in P. rigida and Comatricha laxa and positively correlated in C. confusa, Macbrideora cornea, and Diderma chondrioderma. Bark pH was also positively correlated with the relative abundance of C. confusa, D. chondrioderma, and Physarum nutans and negatively correlated with that of P. rigida, P. cribrata, Enerthnema papillatum, and E. melanospermum. Geographical distribution of corticolous myxomycete communities was determined based on temperature and bark pH, which acted as local barriers in our study area.     

Revisiting the Life Cycle of Dung Fungi,Including Sordaria fimicola

Dung fungi, such as Sordaria fimicola, generally reproduce sexually with ascospores discharged from mammalian dung after passage through herbivores. Their life cycle is thought to be obligate to dung, and thus their ascospores in Quaternary sediments have been interpreted as evidence of past mammalian herbivore activity. Reports of dung fungi as endophytes would seem to challenge the view that they are obligate to dung. However, endophyte status is controversial because surface-sterilization protocols could fail to kill dung fungus ascospores stuck to the plant surface. Thus, we first tested the ability of representative isolates of three common genera of dung fungi to affect plant growth and fecundity given that significant effects on plant fitness could not result from ascospores merely stuck to the plant surface. Isolates of S. fimicola, Preussia sp., and Sporormiella sp. reduced growth and fecundity of two of three populations of Bromus tectorum, the host from which they had been isolated. In further work with S. fimicola we showed that inoculations of roots of B. tectorum led to some colonization of aboveground tissues. The same isolate of S. fimicola reproduced sexually on inoculated host plant tissues as well as in dung after passage through sheep, thus demonstrating a facultative rather than an obligate life cycle. Finally, plants inoculated with S. fimicola were not preferred by sheep; preference had been expected if the fungus were obligate to dung. Overall, these findings make us question the assumption that these fungi are obligate to dung.     

Phylogenetic status of Xylaria subgenus Pseudoxylaria among taxa of the subfamily Xylarioideae (Xylariaceae) and phylogeny of the taxa involved in the subfamily

To infer the phylogenetic relationships of Xylaria species associated with termite nests within the genus Xylaria and among genera of the subfamily Xylarioideae, β-tubulin, RPB2, and α-actin sequences of 131 cultures of 114 species from Xylaria and 11 other genera of the subfamily were analyzed. These 11 genera included Astrocystis, Amphirosellinia, Discoxylaria, Entoleuca, Euepixylon, Kretzschmaria, Nemania, Podosordaria, Poronia, Rosellinia, and Stilbohypoxylon. We showed that Xylaria species were distributed among three major clades, TE, HY, and PO, with clade TE—an equivalent of the subgenus Pseudoxylaria—encompassing exclusively those species associated with termite nests and the other two clades containing those associated with substrates other than termite nests. Xylaria appears to be a paraphyletic genus, with most of the 11 genera submerged within it. Podosordaria and Poronia, which formed a distinct clade, apparently diverged from Xylaria and the other genera early. Species of Entoleuca, Euepixylon, Nemania, and Rosellinia constituted clade NR, a major clade sister to clade PO, while those of Kretzschmaria were inserted within clade HY and those of Astrocystis, Amphirosellinia, Discoxylaria, and Stilbohypoxylon were within clade PO.     

A detailed investigation of the Pterocarpus clade (Leguminosae: Dalbergieae): Etaballia with radially symmetrical flowers is nested within the papilionoid-flowered Pterocarpus

The pantropical genus Pterocarpus (Leguminosae: Dalbergieae) with papilionoid flowers, and allied genera in the Pterocarpus clade were sampled for the five molecular markers ITS2, trnL-F, ndhF-rpL32, matK, and rbcL, as part of our ongoing systematic studies in the clade. For wider analyses of the Pterocarpus clade the remaining 14 members of this clade were also sampled for matK. Phylogenetic analyses were performed under the maximum likelihood criterion (ML) and Bayesian criteria. In the five-marker analysis of the core Pterocarpus clade (including 106 accessions) two robustly supported clades were resolved. The first clade includes Centrolobium, Etaballia, Inocarpus, Maraniona, Paramachaerium, Pterocarpus, Ramorinoa, and Tipuana. The second includes all species of Pterocarpus (except P. acapulcensis), Etaballia with radially symmetric flowers, and Paramachaerium. Paramachaerium is placed as sister to the several Pterocarpus species from South America, while Etaballia is resolved within the clade containing the African and Asian species of Pterocarpus. The wider sampled matK data set includes 199 accessions. Discolobium and Riedeliella are recovered as sister to the remaining Pterocarpus clade. Platymiscium is strongly supported as sister to the rest of the members of the clade, and Pterocarpus acapulcensis is also here resolved in a separate lineage from the remaining Pterocarpus accessions. We used the phylogenies to investigate patterns of floral evolvability in the Pterocarpus clade, which include four genera with actinomorphic flowers (Acosmium s.s., Etaballia, Inocarpus and Riedelliela). Our results reinforce the hypothesis that flower evolvability is high in early-branching legume lineages, and that actinomorphy has evolved independently four times in the Pterocarpus clade. In light of our results, the taxonomic status of the monospecific genus Etaballia dubia Benth. was revisited, and the species is synonymized as belonging to Pterocarpus, under the name Pterocarpus dubius Spreng., published in 1827, but hiding in synonymy for nearly two centuries.     

higher-order phylogeny of plasmodial slime molds (Myxogastria) based on elongation factor 1-A and small subunit rRNA gene sequences

The Myxogastria are common soil microorganisms with a life cycle comprised of a plasmodial trophic stage and large fruiting bodies generally visible with the unaided eye. Until now, their classification has been based exclusively on a combination of morphological, ultrastructural, and developmental characters. Our study is the first attempt to examine phylogenetic relationships among these taxa using molecular data. Partial small-subunit ribosomal RNA and/or elongation factor 1-alpha gene sequences were obtained from eleven, mostly field-collected species representing the five orders of Myxogastria. Nineteen sequences were obtained and subjected to phylogenetic analysis together with 10 sequences available from GenBank. Separate and combined analyses of the two data sets support the division of Myxogastria into three distinct groups. The most basal clade consists of the Echinosteliales, an order considered to have affinities with Protostelia. The three species examined possess unpigmented or slightly pigmented spores. The second group consists of Liceales and Trichiales, taxa characterized by the presence of clear, but pigmented, spores. The third group consists of the two remaining orders, Physarales and Stemonitales, both possessing dark spores. This suggests that spore pigmentation is an evolutionarily conservative character in myxogastrians, and that the simple morphology of echinostelids is not a derived feature.     

Relatedness of novel species of Myxidium Bütschli, 1882, Zschokkella Auerbach, 1910 and Ellipsomyxa Køie, 2003 (Myxosporea: Bivalvulida) from the gall bladders of marine fishes (Teleostei) from Australian waters

During a parasitological survey, Myxidium-like spores were identified in the gall bladders of marine fishes from Australian waters. This paper describes four novel species of Ellipsomyxa Køie, 2003, three novel species of Myxidium Bütschli, 1882 and six novel species of Zschokkella Auerbach, 1910 from teleosts from Australian waters using a combination of morphological, biological and molecular characters. Phylogenetic analyses showed a monophyletic relationship of all Ellipsomyxa spp. sequences with Sigmomyxa sphaerica (Thélohan, 1895) and Myxidium queenslandicus Gunter & Adlard, 2008 as sister species to the clade. The validity of genus Sigmomyxa Karlsbakk & Køie, 2012 is discussed. In phylogenetic analyses, the novel species of Myxidium fell within the ‘marine’ clade of Fiala (2006). However, the novel species of Zschokkella fell within the ‘freshwater’ clade of Fiala (2006) and formed a distinct clade with all other sequences of Zschokkella spp. from the gall bladder of marine fish and a sequence of a species of Myxobolus Bütschli 1882, also from the gall bladder of a marine fish. This is the second distinct marine lineage to emerge within the freshwater clade.     

Phylogeny of Rhododendron subgenus Hymenanthes based on chloroplast DNA markers: between-lineage hybridisation during adaptive radiation?

Rhododendron subgenus Hymenanthes comprises >200 highly interfertile species in SE Asia (mainly Himalayas and southern China) plus the 10–11 members of subsection Pontica (excluding R. hyperythrum) distributed outside SE Asia. Parsimony and Bayesian analyses of cpDNA matK and trnL-F sequence data divided Hymenanthes into two clades: clade H, in which two Pontica species and the SE Asian R. adenopodum were sister to a clade of 60 SE Asian species, and clade P comprising eight Pontica species plus R. praevernum, R. calophytum, and R. insigne from SE Asia. If these three species belong in Pontica, they expand its range substantially. However, as they have no morphological links to Pontica, they might descend from clade H species that captured chloroplasts from a now extinct species of Pontica. Either way, their distribution within the Chinese/Himalayan range of Rhododendron indicates an ancestor that came from the north or east to meet the diversifying group of Hymenanthes in the Himalayas, making the SE Asian members of Hymenanthes a polyphyletic group.     

吉林省不同地区基物黏菌湿室培养的初步研究

对采自吉林省不同地区的基物进行了黏菌的湿室培养,共获得5目7科17属42种黏菌,其中柄罐无丝菌（Licea operculata）、钉形钙皮菌（Didymium davus）和长轴绒泡菌（Physarum puniceum）为吉林省新记录种。     

<Emphasis Type="Italic">Sordaria fimicola</Emphasis>-like ascomycete isolated from <Emphasis Type="Italic">Pinus coulteri</Emphasis> needles in Slovakia

This is the first report of Sordaria fimicola-like ascomycete which was encountered during a diversity study of injured tissues of coulter pine in Slovakia. The fungus was identified as Sordaria fimicola by morphological analyses. Sequence analysis of internal transcribed spacer region (ITS) showed that the fungus is highly related to the ITS sequences of several S. fimicola isolates documenting wide ecological valence and geographical distribution of S. fimicola-like ascomycetes.     

Marine fungal lineages in the Hypocreomycetidae

Phylogenetic analyses of DNA sequences from protein coding and ribosomal nuclear loci support the placement of a number of marine fungal species associated with a well-supported clade containing fungicolous species of Melanospora and wood inhabiting Coronophorales. Three subclades containing marine species were recovered including Torpedospora radiata plus T. ambispinosa, Swampomyces species plus Juncigena adarca, and two Etheirophora species plus additional Swampomyces species. The monophyly of these three subclades, as well as a subclade containing representatives of Coronophorales and Melanospora, is well supported statistically. However, relationships among the different subclades remain largely unresolved. A sister relationship for this group with Hypocreales is significantly supported by Bayesian and ML methods. In addition to the Halospheariales and Lulworthiales, this clade, which is characterized by considerable morphological and ecological diversity, represents a third major clade of marine Sordariomycetes.