Description and life cycle of a new Physarum (Myxomycetes) from the Atacama Desert in Chile

A new species of Physarum (Myxomycetes), Physarum atacamense is described in this paper, and details are provided on its life cycle as observed in spore-to-spore culture in agar. The new species was collected during studies of the Atacama Desert in Chile. It has been collected directly in the field and isolated in moist chamber cultures prepared with material from an endemic cactus. The combination of characters that make this species unique in the genus are its large fusiform nodes of the capillitium, its long, bicolored stalk and the very dark brown and densely warted angular spores. The morphology of specimens of this myxomycete was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details and life cycle stages are included in this paper. The importance of resistant stages in the life cycle of this myxomycete is stressed, and the close association of this myxomycete with its plant substrates is discussed.     

Two new species of Perichaena (Myxomycetes) from arid areas of Russia and Kazakhstan

Two new myxomycete species from dry steppe and desert communities of the Caspian Lowland (Russia) and central Kazakhstan are described and illustrated. They are placed tentatively within genus Perichaena, which does include species with a reduced capillitium and single-layered peridium. Both species were found repeatedly in moist chamber cultures; P. heterospinispora appeared on leaf litter and twigs, whereas P. polygonospora occurred on leaf litter and weathered dung of rodents. Both species have spore ornamentation that is unique for members of genera Licea and Perichaena. The spore ornamentation of the first species includes scattered large, pyramid-like spines 0.9-1.2 microm high that sometimes have enlarged ends. Among these spines the spore surface is covered by evenly and densely distributed warts that are visible only by SEM. The second species is characterized by angular spores with a coarse network of rounded ridges. The areas among these ridges bear scattered composite warts 0.3-0.5 microm high that sometimes coalesce to form clusters but more often are distributed evenly and densely and are visible only by SEM. The stability of the taxonomic characters of both species was confirmed by several collections from different regions obtained in 2 y. The morphology of the fructifications of the two myxomycetes was examined with both scanning electron and light microscopy, and micrographs of all relevant features are presented.     

Spore to spore culture of Didymium operculatum, a new Myxomycete from the Atacama Desert of Chile

A new species of Didymium (Myxomycetes), D. operculatum, is described in this paper, and details of its life cycle are provided. The new species was recorded during studies of the Atacama Desert in Chile. It has been collected directly in the field and isolated in moist chamber cultures prepared with material from an endemic cactus. The distinguishing characters of this species are its dehiscence by means of an apical operculum combined with a whitish calcareous stalk and the banded reticulate ornamentation of the spores. The morphology of this new myxomycete was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included in this paper. Some comments are made on the patterns of distribution of Didymium species in arid lands and adaptive characters enabling this genus to colonize such extreme environments. It is proposed that a longer cycle and the ability to resort to resistant forms many times during their development reflect the response of these myxomycetes to the largely unfavorable conditions of their environment.     

Inflorescences of Neotropical herbs as a newly discovered microhabitat for myxomycetes

An assemblage of myxomycetes associated with inflorescences of large Neotropical herbs, a microhabitat not previously known to support these organisms, is described and characterized ecologically from a number of study sites in Costa Rica, Ecuador, and Puerto Rico. Thirty-one different taxa were found among 652 specimens of myxomycetes recorded in the field or obtained from 358 moist chamber cultures prepared with decaying floral parts. A comparison with the results of 696 moist chamber cultures prepared with various other litter substrates showed that thirteen myxomycete taxa occurred more often on inflorescences. Six taxa had a strong preference for this microhabitat, and three of those seem to be new for the Neotropics. Correspondence analysis of the data set compiled for inflorescences indicated that the assemblage of myxomycetes was relatively consistent across all of the various study sites. The actual myxomycete substrates were the rapidly decaying floral parts enclosed by the massive, still living bracts. Richest in myxomycetes were species of Heliconia and Costus. Here, nectar residuals probably promoted a rapidly developing community of yeasts and bacteria. A high density of these organisms was indicated by the frequent occurrence of myxobacteria in the moist chamber cultures prepared with floral parts. Results from canonical correspondence analysis suggested that a substrate pH between 8 and 9 and the presence of massive, compact inflorescences on plants occurring at lower elevations in localities with moderate annual rainfall provide optimal conditions for inflorescence-inhabiting myxomycetes. An incidental dispersal of myxomycete spores by birds that pollinate the flowers or feed upon the fruits seems possible and may have accounted for the high degree of preference exhibited by some of the inflorescence-inhabiting myxomycetes, for which the term "floricolous" is proposed.     

Spatiotemporal distribution and dynamic changes of myxomycetes in subtropical forests of China

The spatiotemporal distribution and dynamic changes of species composition of myxomycetes in humid subtropical forests of Houhe National Nature Reserve in southern China were studied by collecting samples of bark and ground litter within four seasons for isolation of myxomycetes in moist chamber cultures and by collecting fruiting bodies in the field from June to October. A total of 725 specimens of myxomycete fruiting bodies representing 77 species of 25 genera were registered, among them 302 records/51 species from field collections and 423 records obtained from 600 moist chamber cultures of ground litter and bark of living trees, which resulted in 35 and 39 species, respectively. Cornuvia serpula and Perichaena microspora were recorded for the first time in China. Both myxomycete species richness and diversity were significantly different in ground litter among sites and field collections among months. NMDS combined with Permanova indicated that the site had a greater impact on the myxomycete community of bark and litter than the season, while the month of field collections had a greater impact than the sampling sites. CCA and VPA analysis showed that the bark-inhabiting myxomycete species were mainly affected by spatial variables, while the litter-inhabiting and field collected species were more affected by climatic factors.     

Description and culture of a new succulenticolous Didymium (Myxomycetes)

A new succulenticolous Myxomycete species, Didymium wildpretii, found on decaying remains of various species of cacti, is described from two arid zones of the world. This species was collected from central Mexico, at the southern limit of the Chihuahuan Desert, and from the Canary Islands (Spain). The new species has small, pale yellow sporocarps, 0.1-0.7 mm high, that are sessile or have short, orange-yellow, calcareous stalks and small, uniformly warted spores. The stability of the taxonomic characters of the species was confirmed with both moist chamber cultures and spore-to-spore culture on agar. Life cycle events are described from germination to sporulation. Myxomycete specimens were examined with scanning electron microscopy and light microscopy, and micrographs of relevant morphological details are included.     

Vertical distribution and assemblages of corticolous myxomycetes on five tree species in the Great Smoky Mountains National Park

Corticolous myxomycetes of the Great Smoky Mountains National Park were studied in relation to their association with certain tree species and height of occurrence in the forest canopy. Using the double-rope climbing method, bark was collected at 3 m increments to the tops of trees of five different species. Bark samples from 25 trees were used to prepare 418 moist chamber cultures maintained and observed 4 wk. Eighty-four myxomycete species were identified, including 30 species not known to occur in the park. Tree species, pH, height in tree and water-holding capacity of the bark samples were analyzed to determine the relationships of myxomycete assemblages cultured on the bark. Results suggested that myxomycete community composition among selected tree species were similar, but occurrence and abundance of certain species were related to differences in bark pH. Community similarity values among trees of different species show that trees with the most similar myxomycete communities also have the most similar bark pH. Most myxomycete species in this study have a pH optimum. No variation in species richness was detected at different heights in the trees, and most species were obtained at all heights up to at least 24 m. The water-holding capacity of the bark could not be correlated with species richness or abundance of myxomycetes that inhabit the bark of living trees. This is the first study to characterize myxomycete communities of tree canopies.     

Myxomycetes developed on litter of common Finnish trees in moist chamber cultures

Fallen leaves were collected from the Finnish trees Alnus gtutinosa & A. incana, Betula pendula & B. pubescens, Picea abies, Pinus sylvestris and Populus tremula , and used to establish 400 moist chamber cultures. From these emerged 132 specimens of Myxomycetes belonging to 14 species. One of them, Didymium dubium Rostaf. was also cultivated from spore to spore in artificial media. The three Arcyria species that emerged developed only on coniferous litter and the four Didymium species only on deciduous litter. Echinostelium minitum de Bary is the only myxomycete species that emerged on leaves of all the five trees.
Alnus litter gave rise to the greatest number of myxomycete specimens. Betula leaves seemed to be the most unfavourable of the substrates. The common species of Myxomycetes that have appeared only on bark of living trees in the moist chambers set up by the author include Paradiacheopsis fimbriata (G. Lister & Cran) Hertel and P. solitaria (Nann.–Brem.) Nann.–Brem. Species occurring only on deciduous leaves or grains are Didymium difforme (Pers.) S. F. Gray, D. dubium Rost. and D. squamulosum (Alb. & Schw.) Fr.     

New foliicolous lichens from New Zealand 3

Podotara gen. nov. (incertae sedis) is described. It is based on the foliicolous taxonP. pilophoriformis sp.nov., which is described and illustrated. Characteristic of the new genus and species are globose and stipitate apothecia and 3-septate, hyaline, thin-walled ascospores with annular thickening of the septa.Scoliciosporum lividum sp. nov. (Scoliciosporaceae) differs from all species of its genus known to date by its leprose grey thallus, its livid, globose, dull apothecia, and its 3-septate ascosoores spirally contorted in the ascus.     

Biecheleria tirezensis sp. nov. (Dinophyceae,Suessiales), a new halotolerant dinoflagellate species isolated from the athalassohaline Tirez natural pond in Spain

A new euryhaline and eurythermal dinoflagellate species, Biecheleria tirezensis sp. nov., is described based on samples taken from an extreme environment, the athalassohaline and particularly sulphate-rich Tirez natural pond (Spain). This species is able to survive in salinities from almost fresh water up to 56 and over a 5–25°C temperature range. Thus, the ecological characteristics of this isolate differentiate it from other species of the same genus. Its morphology, as examined by light, scanning and transmission electron microscopy, shows that the cells are almost spherical, with several series of amphiesmal vesicles. It also has a single elongate amphiesmal vesicle (EAV) observed by SEM and the eyespot has a type E structure, typical of Biecheleria. Spherical and smooth cysts were observed in old cultures. The pigment composition is typical of a peridinin-containing dinoflagellate. Phylogeny inferred from nuclear rDNA SSU, ITS and LSU sequences showed the isolate belongs to the genus Biecheleria, closest to B. cincta and B. brevisulcata. Modelling and analysis of the secondary structure of its ITS2 region, and that of other species of the same genus and some representatives of the most closely related genera, indicated that the isolate represents a new species clearly separated from but related to B. cincta. The criterion of the presence of Compensatory Base Changes (CBCs) in the secondary structure of the ITS2 region as an indicator of species differentiation confirmed this, supporting the establishment of the Tirez pond isolate as a new species of Biecheleria.     

Macroecology of high-elevation myxomycete assemblages in the northern Neotropics

A number of recent studies have been directed towards developing a more complete understanding of myxomycete ecology throughout the world. However, the lack of comparative data obtained using standard methodologies makes the results of these studies somewhat speculative. The objective of this investigation was to examine the evidence of macroecological patterns in myxomycete assemblages in high-elevation areas of the northern Neotropics. For this, a series of study areas in Mexico, Guatemala, and Costa Rica, as well as two external study areas (one in the United States and the other in Thailand), were selected to compare the diversity-environment relationships exhibited by myxomycetes. Altogether, the 2592 moist chamber cultures prepared yielded a total of 1377 myxomycete records, representing 89 different species. A trend of decreasing species richness with decreasing latitude was observed for the species assemblages associated with the study areas in the Neotropics. As latitude increased, species assemblages in the Neotropical study areas became increasingly similar to the temperate study area. The difference in species richness between study areas in Mexico and Thailand, along with the results obtained for a series of macroclimatic patterns evaluated in the study areas of the Neotropical region, suggests that forest structure plays an important role in the structure of myxomycete assemblages. In contrast, soil chemical characteristics and the pH of the substrates present seem to be indirectly related to the diversity estimators used for analysis, suggesting that they are probably more important at a smaller ecological scale.     

Morphological and molecular characterization of a new succulenticolous Physarum (Myxomycetes,Amoebozoa) with unique polygonal spores linked in chains

A new plasmodiocarpic and sporocarpic species of myxomycete in the genus Physarum is described and illustrated. This new species appeared on decayed leaves and remains of succulent plants (Agave, Opuntia, Yucca) growing in arid zones. It differs from all other species in the genus in having polyhedral spores linked in chains like a string of beads, a unique feature within all known myxomycetes. Apart from detailed morphological data, partial sequences of both the small-subunit ribosomal RNA and elongation factor 1-alpha genes, generated from four isolates collected in two distant regions, i.e., Mexico and Canary Islands, are also provided in this study. Combined evidence supports the identity of the specimens under study as a new species.     

A new species of Waltheria (Sterculiaceae) from Somalia

Waltheria laxa , sp. nov., is described from near Mogadishu in south-central Somalia. The species seems to be unique in the mainly neotropical genus Waltheria in its free stamens. It is also unusual in its comparatively long-pedicelled flowers with a distinctly stipitate ovary.     

Myxomycete biodiversity of the Colorado Plateau

A rapid biodiversity assessment for myxomycetes (plasmodial slime moulds) was carried out during a two-week field trip to the Colorado Plateau (western U.S.A.). Due to the very arid climate of the region, the moist chamber culture technique formed a major part of the survey. A total of 1165 records belonging to 93 species and 1 variety from 27 genera was collected from the 433 moist chamber cultures prepared with the bark surface of living plants, litter and weathered dung of herbivorous animals. Only 31 specimens of 16 wood-inhabiting species were collected in the field, mainly at higher elevations. Subsequent moist chamber cultures produced numerous bark-inhabiting species that are usually considered to be rare, including Echinostelium coelocephalum, Protophysarum phloiogenum, and Macbrideola declinata. The most common litter-inhabiting species were Didymium mexicanum and Badhamia melanospora (mainly on decaying parts of Opuntia spp. and Agave spp.); the most abundant coprophilous species were Badhamia cf. apiculospora, Fuligo cinerea, Perichaena liceoides, and Licea tenera. Both, species richness and diversity, increase from sagebrush desert to pine-juniper open woodland and pine-oak woodland. The myxomycete biota of the Colorado Plateau displays a high level of similarity to those of other arid regions of the world (mean coefficient of community C_s = 0.67), differing considerably from temperate (mean C_s = 0.34), boreal (mean C_s = 0.49) and tropical biotas (mean C_s = 0.42).     

Influence of bark pH on the occurrence and distribution of tree canopy myxomycete species

This study compares the occurrence and distribution of myxomycete species in the canopy of living trees and neighboring grapevines. Corticolous myxomycetes of three temperate forests in southeastern USA were studied on six tree species (30 trees) and grapevines (30 vines) to determine distribution and occurrence of myxomycete species relating to geographic location, host species, and bark pH. The double-rope climbing technique was used to access the canopy and sample bark up to 16.5 m. Bark samples were examined in 580 moist chamber cultures and 44 myxomycete species were identified representing 21 genera, averaging 3.0 +/- 2.1 species per sample site. Jaccard's coefficient determined community similarity between five individuals of six tree species, Acer saccharum, Fraxinus americana, Liquidambar styraciflua, Liriodendron tulipifera, Platanus occidentalis and Tsuga canadensis, and neighboring grapevines, Vitis aestivalis and V. vulpina. Vertical variation in species richness was significantly different only for Platanus occidentalis and might be attributable to flaking of bark with increasing height in the canopy. Tsuga canadensis and neighboring grapevines had greatest community similarity. Cribraria violacea was observed on all tree and grapevine species except T. canadensis and neighboring grapevines. Occurrence and species assemblages of myxomycetes were associated with bark pH, not geographic location. Bark of V. aestivalis (pH 4.5) was more acidic than neighboring T. canadensis (pH 4.1), compared to grapevines of the same species neighboring other tree species. Results indicated that most species are not regionally restricted, and although some myxomycetes are associated with a certain pH range, others develop on any substratum. Future research protocols for corticolous myxomycetes should emphasize sampling adequate amounts of substrata in a local region from different host species that have a wide range of bark pH, ensuring a representative sample of species for an entire region.     

Lepidoderma cristatosporum, a new species of myxomycete from Australia

A new species of myxomycete, Lepidoderma cristatosporum, is described from Australia. This species is represented by material collected on subantarctic Macquarie Island. Photographs of fruiting bodies and morphological features as observed under light microscopy are provided, along with micrographs of spore ornamentation as observed by scanning electron microscopy. In addition, the new species is compared with other taxa belonging to the genera Lepidoderma and Diderma, especially with the type material of Lepidoderma crustaceum, a very similar species, and Diderma ochraceum and D. sauteri, two species also muscicolous, for which microphotographs are provided.     

后河保护区柳杉林中黏菌群落组成

柳杉是中国特有树种,对于广泛分布于森林生态系统的黏菌而言,单纯的柳杉林是一种特殊的生境。为探索柳杉林中黏菌的物种多样性,本研究在武陵山区东北部的湖北省后河国家级自然保护区柳杉林样地中采集柳杉树皮和凋落物,在120个培养湿室中,发生黏菌的湿室68个,占56.67%。从两种基物上获得黏菌6目7科12属24种,优势种为混淆筛菌Cribraria confusa,相对丰度达到19.01%。柳杉林凋落物上发生的黏菌种类和数量高于柳杉树皮,凋落物和柳杉树皮上发生的黏菌共有种为4种,种群间的Sørensen相似性系数为Cs=0.333。在不同季节间,黏菌物种的群落组成与多样性也表现出差异,春季Shannon-Wiener多样性指数Hʹ=0.2987±0.1564,夏季Hʹ=0.1105±0.0949,秋季Hʹ=0.1968±0.0589,冬季Hʹ=0.2726±0.0875。黏菌物种数量发生最多的是春季和冬季,均有15种,仅在春季发生的黏菌物种为粗壮发菌Comatricha suksdorfii、鲜黄绒泡菌Physarum luteolum、暗红团网菌Arcyria denudata和极小无丝菌Licea minima,仅在冬季发生的黏菌物种为钙丝绒泡菌Physarum decipiens、小筛菌Cribraria microcarpa和暗褐无丝菌Licea belmontiana。典型对应分析（canonical correspondence analyses,CCA）表明,影响柳杉林中黏菌物种群落组成与多样性的主要环境因素是基物类型。