Systematic studies on coprinoid and psathyrelloid agarics (Agaricales, Basidiomycota, Fungi) of Kerala state

Abstract

Fungi are incredibly diverse and can be found in a wide range of life forms, making them ubiquitous organisms in the ecosystem. Their ecological and economic importance cannot be overstated, as they play vital roles in maintaining healthy environments and significantly impact our daily lives. However, despite their significance, fungi remain one of the least explored groups of biodiversity on our planet. Therefore, the greatest challenge of modern fungal taxonomy is to discover and document this tremendous diversity. The present study represents a crucial step in shedding light on the coprinoid and psathyrelloid agarics found in Kerala State. This study forms the first comprehensive effort to document and analyse the diversity of these fungal groups in this region and to unravel their intricate phylogenetic relationships. Coprinoid and psathyrelloid agarics are closely related groups of fungi with several similar features. They encompass a wide array of species, often occupying similar ecological niches and playing similar roles within the ecosystem as they are primarily decomposers, mostly saprophytic, contributing significantly to the decay of wood, dung, grassy debris and other types of forest litter. The present study had the following three objectives: 1. to study the diversity of the coprinoid and the psathyrelloid agarics of Kerala State; 2. to prepare a systematic account of the discovered taxa with keys, detailed descriptions, photographs of microscopic structures and colour photographs of basidiocarps; 3. to study the evolutionary relationships of the discovered taxa using the methods of molecular phylogenetics are the objectives of the present study. This study provides a detailed account of the coprinoid and psathyrelloid agarics collected from various localities of Kerala State. In this treatise, a total of 35 species representing 9 genera belonging to two families, namely Psathyrellaceae and Agaricaceae, are fully described, discussed and illustrated. The species descriptions were supplemented with author citations, synonyms and collection details. In addition, artificial keys to the family, genera, sections and species were provided wherever applicable. The major outcome of this study is the discovery of 20 species new to science. The new species included six species of Coprinopsis, five species of Candolleomyces, three species each from the genera Parasola and Psathyrella and one species each from the genera Tulosesus, Narcissea and Coprinus. Of these new species, five species, namely Coprinopsis fragilis, C. minuta, C. squamulosa, Parasola parvula and P. psathyrelloides were validly published during the course of this study. Among the 15 previously known species discussed in this treatise,9 were found to be the first records from India including Parasola lilatincta which was published during the course of this study and 11 formed the first records from Kerala. A total of 96 nucleotide sequences were generated as part of this study, which comprise 52 ITS and 44 nLSU sequences including the sequences from additional collections. All the 35 species described in this treatise successfully yielded ITS sequences. The Maximum Likelihood (ML) analyses were conducted using the ITS sequences. Nine separate data matrices were prepared for conducting the phylogenetic analyses of the discovered taxa. The phylogenetic analyses based on the nine data matrices resulted in nine phylograms. Of these nine phylograms, the first phylogram showed the overall placement of all the thirty- five species discovered and described during this study. The remaining eight phylogenetic trees illustrated the phylogenetic findings of the nine genera (Candolleomyces, Coprinellus, Coprinopsis, Coprinus, Hausknechtia, Narcissea, Parasola, Psathyrella and Tulosesus).