The Antarctic region is one of the most extreme environments on Earth, characterized by high UV radiation, elevated salinity, limited availability of water and nutrients, and extremely low temperatures. While studies on fungi often focus on filamentous forms and bioprospecting, macroscopic fungi, such as those in the order Agaricales, receive less attention. Since the discovery of Omphalina antarctica in the 1950s, later reclassified as Arrhenia, the genus Omphalina has been represented by Omphalina pyxidata and Omphalina rivulicola in Antarctica. Given the anticipated increase in fungal biodiversity in Antarctica due to climate change, investigating fungal species distribution and monitoring existing populations is crucial. Based on comprehensive morphological and phylogenetic analyses of Agaricales fungi from the Byers Peninsula, Livingston Island, Antarctica, we propose the formal description of four novel species within the genus Omphalina (family Omphalinaceae): Omphalina deschampsiana, Omphalina ichayoi, Omphalina frigida, and Omphalina schaeferi. The unique morphological characteristics of these species, along with molecular data from DNA sequence analyses, clearly differentiate them from other extant species within the genus. These new species identifications augment the known fungal biodiversity of Antarctica and underscores the importance of continued research in polar regions.

Microbial biofilms are important components in macrophyte decomposition, and their composition depends on the decomposition stage and host plant quality. Here, we investigated how macrophyte tissue quality (i.e., C:N:P stoichiometry and phenolic contents) influences epiphytic microbial biofilms during litter decomposition. Consecutive experiments were conducted to (1) modify the C:N:P stoichiometry and phenolic content of the freshwater macrophyte Elodea nuttallii by manipulating light and nutrient availability and (2) test how the modified tissue quality affected epiphytic microbial biofilm diversity and community composition before and during macrophyte decomposition. Our results showed that shading led to lower C:N ratios (28.6 to 12.6) and higher phenolic content (10.8 to 19.2 µg/mg dry weight). Simultaneously, shading affected the epiphytic bacterial and fungal community composition, and these shifts correlated with the macrophyte C:N ratio. While no effects of macrophyte tissue quality on decomposition rates were observed, the epiphytic bacterial community composition on the litter was significantly affected by light treatment, time, and their interaction. Bacterial community composition shifted from a high abundance of Comamonadaceae to a more diverse community over time. Overall bacterial diversity was lower on the litter grown in the shaded mesocosms. Fungal diversity and community composition during litter decomposition were not affected by litter quality. Overall, our results reveal a structuring role of macrophyte tissue quality on its associated microbial biofilm and uniquely show a continuation of light-driven changes in epiphytic bacterial community composition after exposure. We conclude that light-driven changes in C:N stoichiometry are a crucial factor in shaping epiphytic microbial communities during macrophyte decomposition.

Corticium ochraceofulvum and Corticium subseriale, two taxa with narrowly fusoid leptocystidia currently placed in Phlebia, are studied by morphology and nuclear rDNA sequences. Phylogenetic analyses show that the two species belong in Phanerochaete, despite having constantly clamped hyphae. Study of the type of Xerocarpus cacao shows that it is an older name for Corticium subseriale. The type of Phanerochaete calotricha is studied and material corresponding to the type sequenced. Specimens identified as Phanerochaete calotricha but differing genetically are described as Phanerochaete volubilis. Phanerochaete avellanea and P. ericina are confirmed as members of Phanerochaete based on nrDNA sequences and study of type material. Sequences from North America published as Phanerochaete ericina belong to a different species. Odontia rufobrunnea is identified as an earlier name for Phanerochaete aculeata. Thelephora amphibolia is identified as an earlier name for Phanerochaete cumulodentata. Phanericium is introduced for Corticium tuberculatum and related species, and a new species, Phanericium gemellum, is described. The new combinations Phanericium americanum, P. rodriguezarmasiae, P. subglobisporum, and P. taiwanense are proposed. Corticium cremeo-ochraceum, Corticium joseferreirae, and Phanerochaete pallida are confirmed as distinct species and transferred to Phanerochaetella. An ITS sequence of Phanerochaetella joseferreirae from the type locality is provided and the identity of Corticium queletii is discussed. Two ITS sequences of Phanerochaetella exilis from the vicinity of the type locality are presented. An earlier published sequence of Phanerochaetella exilis is considered to represent an unknown species.

Although knowledge of arbuscular mycorrhizal fungi (AMF) in leaf litter remains limited, reports of their presence in this substrate have become increasingly frequent. However, the factors driving litter colonization and the identity of AMF species occurring in such conditions are still poorly understood. It has been suggested that these fungi may preferentially colonize litter during the early stages of decomposition. However, to date, no study has identified AMF species in this substrate, leaving their diversity, ecological roles, and contribution to decomposition largely unresolved. In light of this, leaf litter samples were collected from three Brazilian Atlantic Forest sites and analyzed using morphological and molecular approaches. According to the analysis, the bag exposure duration, litter quality (determined by a set of chemical: concentrations of carbon, nitrogen, phosphorus and physical traits of leaf (specific leaf area). Leaves that have higher stoichiometric ratios such as C:N and C:P and lower SLA are determined as a lower quality litter, while those having high concentrations of nitrogen and phosphorus and high SLA are determined as a high quality litter), and edaphic factors drove AMF colonization in leaf litter. Diversispora varaderana, Funneliformis caledonius, F. geosporus, Glomus spinuliferum, and Rhizoglomus irregulare were reported for the first time in association with leaf litter. Furthermore, D. varaderana and F. caledonius represented new records for Brazil and the Brazilian Atlantic Forest, respectively. These findings highlight leaf litter as a promising habitat, complementing previous studies on soils for AMF diversity and their ecological role in decomposition, along with its biotechnological applications.

No summary available.

Root-knot nematodes (Meloidogyne spp.) are important pests of numerous crops worldwide. Some members of this genus have a quarantine status, and accurate species identification is required to prevent further spreading. DNA barcoding is a method for organism identification in non-complex DNA backgrounds based on informative motifs in short DNA stretches (≈600 bp). As part of the EU 7th Framework project QBOL, 15 Meloidogyne species were chosen to compare the resolutions offered by two typical DNA barcoding loci, COI and COII, with the distinguishing signals produced by two ribosomal DNA genes (small and large subunit rDNA; SSU ≈ 1,700 and LSU ≈ 3,400 bp). None of the four markers distinguished between the tropical species Meloidogyne incognita, M. javanica and M. arenaria. Taking P ID (Liberal) values ≥0.93 as a measure for species delimitation, the four mtDNA and rDNA markers performed well for the tropical Meloidogyne species complex, M. enterolobii, M. hapla, and M. maritima. Within cluster III A (Holterman et al. Phytopathology, 99, 227–235, 2009), SSU rDNA did not offer resolution at species level. Both mtDNA loci COI and COII did, whereas for LSU rDNA a longer fragment (≥700 bp) is required. The high level of mitochondrial heteroplasmy recently reported for M. chitwoodi (Humphreys-Pereira and Elling Nematology, 15, 315–327, 2013) was not found in the populations under investigation, suggesting this could be a regional phenomenon. For identification of RKNs, we suggest the combined use of SSU rDNA with one of three other markers presented here.