In this study, fungal strain ARI-25-A13 was isolated from an ambrosia beetle collected using beetle traps deployed in an apple orchard. To achieve species-level identification, cultural and morphological characteristics, as well as molecular phylogenetic analyses, were conducted. On potato dextrose agar (PDA), colonies were initially salmon-colored and gradually transitioned to olive to brown with age, whereas colonies on malt extract agar (MEA) retained a salmon coloration throughout incubation. Morphologically, adelophialides were short, thin-walled, and inconspicuous, and neither collarettes nor discrete phialides were observed. Conidia were hyaline, ellipsoidal to cylindrical, frequently slightly curved, and measured 3.7‒5.9 × 1.4‒2.6 μm. Chlamydospores were hyaline, globose to ellipsoidal, formed terminally or intercalarily, occurring singly or in short chains, and measured 4.0‒8.0 × 3.3‒4.5 μm. Phylogenetic analysis based on the internal transcribed spacer (ITS), large subunit ribosomal DNA (LSU), β-tubulin (TUB), and actin (ACT) gene sequences placed ARI-25-A13 in the same clade as Coniochaeta luteoviridis. Collectively, the morphological traits and multilocus phylogenetic evidence support the identification of ARI-25-A13 as C. luteoviridis. This study provides the first mycological characterization of C. luteoviridis isolated from an ambrosia beetle.