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

Association between corticolous myxomycetes and tree vitality in Cryptomeria japonica

The bark of live trees provides an important microhabitat for corticolous myxomycetes. However, the association between the presence of myxomycetes and health of host trees has not been studied in detail. In this study, we aimed to investigate the relationship between tree vitality and myxomycetes on the bark of Cryptomeria japonica trees in a montane forest in western Japan. The vitality of trees was categorized into four grades based on the visual assessment of tree shape and leaf density in the upper branches. Myxomycetes on the bark surface were examined using the moist chamber culture method. A decline in tree vitality increased bark pH and decreased electrical conductivity of the bark exudates. Seventeen myxomycete species were recorded in 74 C. japonica trees. The structure of myxomycete communities varied between healthy and unhealthy trees, and species diversity increased as the vitality declined. The relative abundance of Cribraria confusa decreased as the vitality declined, while that of Paradiacheopsis solitaria increased. The results showed that acidophilic myxomycetes grew on healthy C. japonica bark, but changes in bark pH associated with vitality decline led to the weakening of acidity and shifted the community structure; thus, corticolous myxomycete diversity was enhanced as tree vitality decline.

Ecological assemblages of corticulous myxomycetes in forest communities of the North-East Ukraine

Corticulous myxomycetes remain one of the least surveyed ecological groups of terrestrial protists. These organisms develop on the bark of trees, mostly feeding on bacteria and microalgae. Their microscopic size and fast developmental cycle (3–5 days) complicate the study of these organisms, and therefore data their on ecological relationships and patterns of biodiversity corticulous myxomycetes remain controversial. On the territory of the southwest spurs of the Central Russian Upland (Northeast Ukraine), no special studies on these organisms have been conducted. During 2017–2020, in nine forest sites located in this territory, we collected samples of bark of 16 species of tree plants, on which sporulating myxomycetes were then identified using the moist chamber technique in laboratory conditions. A total of 434 moist chambers was prepared, and 267 (61.5%) of which were found to contain myxomycete fruiting bodies. In total, we made 535 observations, finding 20,211 sporocarps. As a result, in the surveyed territory, we found 38 species of corticulous myxomycetes, belonging to 18 genera, 10 families, 7 orders, and 2 subclasses of Myxomycetes. Among the species of corticulous myxomycetes, the most abundant were Echinostelium minutum, Arcyria pomiformis, Macbrideola cornea, Perichaena chrysosperma, Licea kleistobolus, Paradiacheopsis fimbriata, Cribraria violacea, Enerthenema papillatum, A. cinerea, and L. operculata. The greatest species richness in the examined biota was observed for genera Comatricha, Licea, Paradiacheopsis and Perichaena, families Amaurochaetaceae and Trichiaceae, orders Stemonitidales, Trichiales and Physarales. By species diversity, dark-spored myxomycetes (Collumellomycetidae) somewhat exceeded bright-spored myxomycetes (Lucisporomycetidae). Badhamia versicolor, Didymium dubium, D. sturgisii, Macbrideola decapillata, and Perichaena luteola are new species for the surveyed area. Four species of myxomycetes were collected in Ukraine for the first time: Hemitrichia pardina, Licea floriformis, L. pygmea, and Macbrideola argentea. Quantitative and qualitative structure of myxomycete consortia developing on different species of substrate-forming plants demonstrated significant differences. The highest level of similarity was demonstrated by Fraxinus excelsior and Acer platanoides, and a relatively strong relationship was seen between Pinus sylvestris and Tilia cordata. The central cluster comprised F. excelsior, A. platanoides and P. sylvestris. By the sum of values of Bray-Curtis coefficient, Quercus robur appeared to be most distinctive plant species by quantitative composition of myxomycete consortia. F. excelsior and T. cordata are the most favourable for the development of corticulous myxomycetes. In all the analyzed consortia, the dominant species belonged to the Stemonitidales and Trichiales orders, while the remaining orders were represented by notably fewer species. Relative species richness of Stemonitidales was the highest in consortia of P. sylvestris, the contribution of Liceales was the greatest in A. platanoides and P. sylvestris, the percentage of Echinosteliales and Physarales was the highest on F. excelsior, the share of Cribrariales was especially large on A. platanoides. Trichiales were represented on all the analyzed substrates to almost the same extent. Representatives of Cribrariales and Physarales were completely absent on P. sylvestris, the species of Clastodermatales – on all species of plants, except Q. robur. Prevalence of bright-spored myxomycetes was determined for consortia of Acer platanoides, the dominance of dark-spored myxomycetes – for F. excelsior, P. sylvestris and Q. robur. The obtained data indicate the presence of stable complexes of corticulous myxomycetes, associated with different species of trees in the forest ecosystems of Northeast Ukraine. This encourages further study of the structure of myxomycete consortia with tree species that were not included in this study and determining the influence of physical-chemical properties of the bark of different plant species on the discovered peculiarities of myxomycete communities.

Species diversity of corticolous myxomycetes in Tianmu Mountain National Nature Reserve, China

The species diversity of corticolous myxomycetes on 4 vegetation types in the Tianmu Mountain National Natural Reserve, eastern China, was examined from 2011 to 2012. A total of 1440 moist chamber cultures were prepared with bark samples, which yielded several hundred collections representing 42 species in 20 genera. It was found that 79% of cultures produced some evidence (either plasmodia or fruiting bodies) of myxomycetes. Eight species (Comatricha elegans, Cribraria confusa, Licea pusilla, Cribraria microcarpa, Collaria arcyrionema, Licea biforis, Arcyria cinerea, and Clastoderma debaryanum) were abundant (exceeding 3% of all records), but about a third of all species were classified as rare. Species richness (S = 33) and diversity (exp[H'] = 16.60, S/G = 1.74) of corticolous myxomycetes were the most diverse in the deciduous broadleaf forest. The species recorded from coniferous forest showed the lowest species richness (S = 21) but the highest evenness (J' = 0.91). The cluster analyses were based on the Bray-Curtis similarity matrix, and the results indicated that corticolous myxomycete assemblages were distributed by a seasonal and annual pattern. Canonical correspondence analysis showed that season and pH were key factors in determining species distribution.

Evolution of the plankton paleome in the Black Sea from the Deglacial to Anthropocene

The complex interplay of climate shifts over Eurasia and global sea level changes modulates freshwater and saltwater inputs to the Black Sea. The dynamics of the hydrologic changes from the Late Glacial into the Holocene remain a matter of debate, and information on how these changes affected the ecology of the Black Sea is sparse. Here we used Roche 454 next-generation pyrosequencing of sedimentary 18S rRNA genes to reconstruct the plankton community structure in the Black Sea over the last ca. 11,400 y. We found that 150 of 2,710 species showed a statistically significant response to four environmental stages. Freshwater chlorophytes were the best indicator species for lacustrine conditions (>9.0 ka B.P.), although the copresence of previously unidentified marine taxa indicated that the Black Sea might have been influenced to some extent by the Marmara Sea since at least 9.6 ka calendar (cal) B.P. Dinoflagellates, cercozoa, eustigmatophytes, and haptophytes responded most dramatically to the gradual increase in salinity after the latest marine reconnection and during the warm and moist mid-Holocene climatic optimum. According to paired analysis of deuterium/hydrogen (D/H) isotope ratios in fossil alkenones, salinity increased rapidly with the onset of the dry Subboreal after ~5.2 ka B.P., leading to an increase in marine fungi and the first occurrence of marine copepods. A gradual succession of dinoflagellates, diatoms, and chrysophytes occurred during the refreshening after ~2.5 ka cal B.P. with the onset of the cool and wet Subatlantic climate and recent anthropogenic perturbations.

Aspergillus and Penicillium identification using DNA sequences: barcode or MLST?

Current methods in DNA technology can detect single nucleotide polymorphisms with measurable accuracy using several different approaches appropriate for different uses. If there are even single nucleotide differences that are invariant markers of the species, we can accomplish identification through rapid DNA-based tests. The question of whether we can reliably detect and identify species of Aspergillus and Penicillium turns mainly upon the completeness of our alpha taxonomy, our species concepts, and how well the available DNA data coincide with the taxonomic diversity in the family Trichocomaceae. No single gene is yet known that is invariant within species and variable between species as would be optimal for the barcode approach. Data are published that would make an MLST approach to isolate identification possible in the most well-studied clades of Aspergillus and Penicillium.