Zaanenomyces quadripartis Crous & Osieck, sp. nov.

MycoBank number: MB 841805; Index Fungorum number: IF 841805; Facesoffungi number: FoF;

Etymology. Name refers to the expansion of the WI research infrastructure (D-wing; quadripartis (‘the fourth part’), during the Westerdijk year (2017), celebrating Johanna Westerdijk, who was the first female professor in the Netherlands (10 February 1917).

Mycelium consisting of hyaline, smooth-walled, branched, septate, 1.5 – 2 μm diam hyphae. Conidiophores solitary, arising from superficial mycelium, erect, subcylindrical, unbranched, brown, smooth-walled, 1– 4-septate; base swollen or with rhizoids, conidiophore with or without brown nodulose swellings, thick-walled, 15 –100 × 2.5–3.5 μm. Conidiogenous cells terminal, integrated, forming a rachis with pimple-like denticles, slightly thickened and darkened, not refractive, 0.5 μm diam, 10 – 35 × 2.5 – 3.5 μm. Conidia solitary, forming a dry mass at apex, narrowly obclavate, straight to flexuous, apex subobtuse, base obconically truncate, (1–)4-septate, hyaline, smooth- walled, guttulate, hilum thickened and darkened, 0.5 –1 μm diam, (12 –)23 – 30(– 35) × (2.5 –)3 μm; conidia becoming pro- minently constricted at septa with age.

Culture characteristics — Colonies erumpent, spreading, with sparse aerial mycelium and smooth, lobate margin, reaching 3 mm diam after 7 d at 25 °C. On MEA surface and reverse sienna; on PDA surface and reverse pale luteous; on OA surface pale luteous.

Typus. NETHERLANDS, Utrecht Province, Nieuw Wulven, near Houten, 1.5 m a.s.l., N52°02’45” E05°10’34”, on dead culm of Juncus effusus (Juncaceae), 8 Jan. 2021, E.R. Osieck, HPC 3563 = WI-09/#4195 (holotype CBS H-24849, culture ex-type CPC 41073 = CBS 148310, ITS and LSU sequences GenBank OK664721.1 and OK663760.1).

Additional material examined. NETHERLANDS, Utrecht Province, Nieuw Wul- ven, near Houten, on dead culm of Juncus effusus (Juncaceae), 8 Jan. 2021, E.R. Osieck, HPC 3565 = WI-11, CBS H-24818, culture CPC 41013 = CBS 148272, ITS and LSU sequences GenBank OK664722.1 and OK663761.1.