Acremonium, a versatile genus of fungi, thrives in diverse environments and is utilized in various industrial and pharmaceutical applications. Despite its extensive use, the taxonomic classification of Acremonium has been challenging due to its morphological plasticity and wide ecological distribution. This comprehensive study employs molecular phylogenetic analyses to unveil the polyphyletic nature of Acremonium, categorizing it into distinct orders of Sordariomycetes. The research examines 633 cultures from different global substrates, revealing significant taxonomic revisions and proposing new genera and species.
Polyphyletic Nature and Taxonomic Revisions
Recent advancements in molecular phylogenies have demonstrated that Acremonium is highly polyphyletic. Members of Acremonium s. lat. are now recognized to belong to at least three distinct orders of Sordariomycetes. To establish a natural classification for these fungi, the study conducted systematic analyses on 633 cultures from 89 countries. These cultures were collected from various substrates, including soil, plants, fungi, humans, insects, air, and water.
The phylogenetic relationships were inferred using three loci (ITS, LSU, rpb2), resulting in an overview phylogenetic tree that delimits orders and families. Further analyses combining four loci (ITS, LSU, rpb2, tef-1α) facilitated the delimitation of species at generic and family levels. As a result, the study assigned Acremonium-like species to 63 genera and 14 families within Cephalothecales, Glomerellales, and Hypocreales, introducing five new hypocrealean families.
New Genera and Species Descriptions
Among the significant findings, the study proposed 17 new genera and 63 new combinations, providing descriptions for 65 new species. Notably, one epitype and one neotype were designated to stabilize the taxonomy and usage of older names. The majority of Acremonium s. lat. species were found grouped in genera of Bionectriaceae, including the type species A. alternatum. A phylogenetic backbone tree for Bionectriaceae was constructed, recognizing 183 species and resolving 39 well-supported genera, including 10 new genera.
Key Inferences
• Molecular phylogenies reveal Acremonium’s polyphyletic nature, leading to significant taxonomic revisions.
• The study assigns Acremonium-like species to 63 genera and 14 families, including five new hypocrealean families.
• Descriptions of 65 new species and 17 new genera provide a more refined classification framework.
• DNA barcodes rpb2 and tef-1α are proposed for identifying taxa in Bionectriaceae.
The study highlights the importance of integrating molecular and morphological data to achieve a natural classification of fungi. By providing a comprehensive phylogenetic framework, the research offers valuable insights into the biodiversity and evolutionary relationships of Acremonium-like fungi. This refined classification not only enhances our understanding of fungal taxonomy but also supports various applications in industry and medicine.
Original Article: Stud Mycol. 2023 Jun;105:23-203. doi: 10.3114/sim.2023.105.02. Epub 2023 Jun 2. Hou LW, Giraldo A, Groenewald JZ, Rämä T, Summerbell RC, Zang P, Cai L, Crous PW (2023). Redisposition of acremonium-like fungi in Hypocreales. Studies in Mycology 105: 23-203. doi: 10.3114/sim.2023.105.02.

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