Scytalidium aurantiacum L. Beyer & Klingstrom

3.Scytalidium aurantiacumL. Beyer & Klingström, Svensk bot. Tidskr. 59: 35 (1965) Description and illustration. Klingström and Beyer (1965). Notes. Scytalidium aurantiacum was established to accommodate strain FF 21 isolated from pine pulpwood and strain FF 29 obtained from birch (Betula) pulpwood (Klingström and Beyer 1965). Scytalidium aurantiacum is phylogenetically closely related to S. album, S. assmuthi, S. rodionovae, S. circinatum, S. terrigenum, and S. tongrenense (Figs 1, 2). The distinctions between S. aurantiacum and S. album / S. assmuthi are provided in the notes for S. album and S. assmuthi, respectively. Scytalidium aurantiacum is distinguished from S. rodionovae, S. terrigenum, and S. tongrenense by its unknown sexual morph and hyaline arthroconidia (Klingström and Beyer 1965; Pavlov et al. 2018; Jeong et al. 2025). Scytalidium aurantiacum differs from S. circinatum by its bacilliformia arthroconidia, globose, or ellipsoidal chlamydospore-like cells (Klingström and Beyer 1965; Sigler and Wang 1990). Additionally, based on a pairwise comparison of ITS and LSU, S. aurantiacum (ex-type CBS 374.65) differs from S. rodionovae (ex-type 3 C) by 9 % (49 / 531 bp, five gaps) in the ITS and 9.8 % (88 / 896 bp, 61 gaps) in the LSU; from S. circinatum (ex-type CBS 654.89) by 8.9 % (47 / 530 bp, five gaps) in the ITS and 3.2 % (19 / 590 bp, no gap) in the LSU; from S. terrigenum (ex-type KNUF- 23-236) by 2.5 % (13 / 528 bp, one gap) in the ITS and 8.4 % (822 / 897 bp, 62 gaps) in the LSU; from S. tongrenense (ex-type CGMCC 3.28994) by 6.3 % (33 / 522 bp, six gaps) in the ITS and 8.8 % (79 / 896 bp, 79 gaps) in the LSU. This species not only causes blue stain in wood but also exhibits strong antagonistic effects against various wood-decaying fungi, particularly remaining effective at low temperatures (10 ° C) (Klingström and Beyer 1965; Strunz et al. 1972; Cease et al. 1989). Furthermore, the antibiotic metabolite scytalidin produced by S. aurantiacum has demonstrated antifungal activity, making it a candidate for antifungal agent development (Ayer et al. 1993). Dirginčiutė-Volodkienė and Pečiulytė (2011) demonstrated that S. aurantiacum exhibits significant tolerance to copper pollution, indicating its potential as a bioindicator for copper contamination and a candidate species for bioremediation applications.