Design of potentially universal SSU primers in myxomycetes using next-generation sequencing

Catalogue of fungi in China 4: Didymiaceae and Physaraceae (Myxomycetes)

Myxomycetes play crucial ecological roles, yet their species diversity, distribution, and taxonomic relationships remain poorly understood. In this study, we examined 104 specimens from 19 provinces in China. Through morphological analysis, we identified a group of species with reduced lime formation, a feature typically associated with the Physaraceae, but with key morphological similarities to the Diderma. A comprehensive phylogenetic analysis was conducted using three genes (nSSU, EF-1α, and COI), resulting in a dataset of 452 sequences from 116 species. Notably, we identified a distinct clade within Didymiaceae containing species with fewer lime knots, a trait traditionally linked to Physaraceae. This clade, designated as the new genus Neodiderma, was phylogenetically positioned as a sister group to Diderma, potentially representing a transitional group between Didymiaceae and Physaraceae, supported by both morphological and molecular evidence. Eleven new species - N. macrosporum, N. pseudobisporum, N. verrucocapillitium, N. rigidocapillitium, N. rufum, Physarum guangxiense, P. subviride, P. nigritum, P. biyangense, P. neoovoideum, and P. jilinense - were identified from China, and their phylogenetic positions were analysed. Additionally, N. spumarioides (formerly Diderma spumarioides) was recombined. The new and recombined species were formally described and illustrated, and a key to the sections and species of Neodiderma and Physarum was provided.

Two New Species of the Genus Diderma (Physarales, Didymiaceae) in China with an Addition to the Distribution

Myxomycetes are an important component of terrestrial ecosystems, and in order to understand their diversity and phylogenetic relationships, taxonomic issues need to be addressed. In our 1985-2021 biodiversity investigations in Shaanxi Province, Jilin Province, the Inner Mongolia Autonomous Region, Hubei Province, and Henan Province, China, Diderma samples were observed on rotten leaves, rotten branches, and dead wood. The samples were studied, based on morphological features coupled with multigene phylogenetic analyses of nSSU, EF-1α, and COI sequence data, which revealed two new species (Diderma shaanxiense sp. nov. and D. clavatocolumellum sp. nov.) and two known species (D. radiatum and D. globosum). In addition, D. radiatum and D. globosum were newly recorded in Henan Province and the Inner Mongolia Autonomous Region, respectively. The paper includes comprehensive descriptions, detailed micrographs, and the outcomes of phylogenetic analyses for both the newly discovered and known species. Additionally, it offers morpho-logical comparisons between the new species and similar ones.

Allorecognition behaviors in Myxomycetes respond to intraspecies factors

Myxomycetes are multinucleate unicellular organisms. They form a Plasmodium that moves by protoplasmic flow and prey on microorganisms. When encountering intraspecifics, the plasmodium has the capacity for 'fusion', actively approaching and fusing its cells, or 'avoidance', altering its direction to avoid the other individual. This is an allorecognition ability. However, it remains unclear whether the range of allorecognition extends to other species, and its ecological significance is also obscure. Here, we conducted a quantitative evaluation of contact responses from closely related species of plasmodium to clarify the range of allorecognition behaviors in Myxomycetes. Behavioral assays demonstrated that allorecognition behaviors are specifically observed within individuals of the same species, indicating that these behaviors are a phenomenon unique to intraspecies interactions. Myxomycetes allorecognition is an extremely narrow and inward-focused behavior, suggesting a highly specialized mechanism.