Xenoacrodontium juglandis Crous, sp. nov.

MycoBank number: MB 841827; Index Fungorum number: IF 841827; Facesoffungi number: FoF12730;

Etymology. Name refers to the host genus Juglans from which it was isolated.

Mycelium consisting of hyaline, smooth-walled, branched, septate, 1–1.5 μm diam hyphae. Conidiophores reduced to conidiogenous cells arising directly from hyphae, hyaline, smooth- and thin-walled, subulate, straight to flexuous, prolif- erating sympodially, forming a rachis in upper part, 20 – 40 × 2 – 3 μm, with multiple subdenticulate loci, slightly thickened and refractive, not darkened. Conidia solitary, hyaline, aseptate, smooth- and thin-walled, guttulate, ellipsoid, with obtuse apex, (4 –)5(– 6) × 2(– 2.5) μm; hilum slightly thickened, not darkened, 0.5 μm diam.

Culture characteristics — Colonies erumpent, spreading, surface folded, with moderate aerial mycelium and feathery, lobate margin, reaching 12 mm diam after 2 wk at 25 °C. On MEA surface pale luteous, reverse ochreous; on PDA and OA surface and reverse pale luteous.

Typus. NETHERLANDS, Gelderland Province, Beuningen, river Waal, on Jug­ lans regia (Juglandaceae), 17 Oct. 2020, A.L. van Iperen, HPC 3489 (holotype CBS H-24840, culture ex-type CPC 40016 = CBS 148301, ITS, LSU, actA, cmdA, his3, rpb2 and tef1 (first part) sequences GenBank OK664746.1, OK663785.1, OK651136.1, OK651145.1, OK651150.1, OK651176.1 and OK651194.1)

Notes — Acrodontium was shown to be a genus in Terato­-sphaeriaceae, with several acrodontium-like species belonging to other orders (Videira et al. 2016). Xenoacrodontium is presently a monotypic genus in a new family, Xenoacrodonti­ aceae, clustering with isolate CBS 580.67 (isolated as culture contaminant, Houston, Texas, and identified as Acrodontium salmoneum), which appears to represent a second species in the genus.

Based on a megablast search of NCBIs GenBank nucleotide database, the closest hits using the ITS sequence had highest similarity to ‘Acrodontium salmoneum’ (strain ANER3, GenBank MK370695.1; Identities = 466/511 (91 %), 17 gaps (3 %)), Stachybotrys reniformis (strain CBS 136198, GenBank KU846740.1; Identities = 494/575 (86 %), 29 gaps (5 %)),and Stachybotrys nephrospora (strain ATCC 18839, GenBank AF081476.2; Identities = 494/575 (86 %), 29 gaps (5 %)). Closest hits using the LSU sequence are ‘Acrodontium sal­ moneum’ (strain CBS 580.67, GenBank MH870773.1; Identities= 793/800 (99 %), no gaps), Sarocladium brachiariae (as Sa­ rocladium sp. XBL-2015; strain HND5, GenBank KP715271.1; Identities = 762/800 (95 %), no gaps), and Sarocladium impli­ catum (strain CBS 125892, GenBank MH875549.1; Identities= 763/802 (95 %), two gaps (0 %)). Only distant hits with members of Hypocreales were obtained when the actA, cmdA, his3, rpb2 and the tef1 (first part) sequences were used in blastn and megablast searches.