<i>Acremonium quercivorum</i> ( <i>Hypocreales, Sordariomycetes</i> ), a New Species from Oak ( <i>Quercus</i> spp.) Growing in Algeria

<i>Acremonium</i> is a cosmopolitan and diverse genus of filamentous fungi, commonly isolated from soil and plant material, with several species recognized as opportunistic pathogens in both plants and humans. In this study, a novel species, <i>Acremonium quercivorum</i> sp. nov., is described from declining oak (<i>Quercus</i> spp.) trees in Algeria. This species is characterized by thin-walled hyphae, conidia oblong-ellipsoidal, and rounded at the apex, and subulate phialides with a thin neck at the apex. The multi-locus phylogenetic analyses combining ITS, LSU, RPB2, and TEF1 sequence data provide robust evidence supporting its distinction from <i>A. egyptiacum</i> and other closely related taxa. Comprehensive morphological descriptions, micrographs, and phylogenetic analyses of the new taxon associated with oak dieback are presented.