New insights into acremonium-like fungi in Hypocreales: A taxonomic and phylogenetic perspective

Abstract

Acremonium-like fungi represent a morphologically reduced and polyphyletic group with ecological roles ranging from saprophytes and endophytes to opportunistic pathogens, and with demonstrated potential for producing bioactive secondary metabolites. Convergent morphologies and incomplete molecular data have long hampered their taxonomic resolution. Recent studies, combining morphological features, phylogenetic analyses, and ecological and host associations have classified acremonium-like species within the orders Cephalothecales, Coniochaetales, Glomerellales, and Hypocreales. Furthermore, Acremonium s. str. is restricted to the family Bionectriaceae. However, many acremonium-like species remain to be discovered, and there are still gaps in our understanding of their ecological functions and potential applications in biotechnology. In this study, we evaluated 402 isolates of acremonium-like fungi from the CBS culture collection, including isolates that had not yet undergone molecular analysis. Isolates were analysed based on morphological characters and molecular phylogeny, for which DNA sequence data were obtained from the internal transcribed spacer regions 1 and 2 and 5.8S nuclear ribosomal RNA gene (ITS), partial 28S large subunit (LSU) nrDNA, and the protein-coding genes RNA polymerase II second largest subunit (RPB2) and translation elongation factor 1-alpha (TEF1). Our results place those isolates into the orders Hypocreales and Trichosphaeriales, distributed in 18 families and 149 species. The most represented family is Bionectriaceae, followed by Sarocladiaceae and Trichosphaeriaceae. We introduce two new families, seven new genera, and 33 novel species, along with four new combinations. This study provides a robust phylogenetic framework for the order Hypocreales, resolving 29 families, thereby stablishing a strong foundation for future ecological, medical, and biotechnological studies on this taxonomically complex group.