Neochalara spiraeae Crous, sp. nov.

MycoBank number: MB 841799; Index Fungorum number: IF 841799; Facesoffungi number: FoF;

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

Mycelium consisting of hyaline, smooth-walled, branched, septate, 3 – 4 μm diam hyphae. Conidiophores arising from bulbous base, or as extension of hyphae, frequently aggregated, cylindrical, brown, erect, thick-walled, unbranched, straight to slightly bent, 1– 4-septate, sometimes with the basal cell inflated, with terminal conidiogenous cell, 100 –170 × 6 – 8 μm. Conidiogenous cells phialidic, brown, smooth-walled, consisting of a subcylindrical venter that gradually merges into a pale brown cylindrical collarette; venter 30 – 40 μm long, 7–10 μm wide, neck collarette 30 – 50 μm long, 4 – 5 μm wide, ratio of mean lengths of collarette and venter 1 : 1. Conidia in long, unbranched chains, cylindrical with both ends truncate with marginal frill, medianly 1-septate, hyaline, guttulate, smooth- walled, (11–)12 –14(–16) × (3 –)4(– 4.5) μm, av. 13 × 4.

Culture characteristics — Colonies flat, spreading, with sparse aerial mycelium and smooth, lobate margin, reaching 30 mm diam after 7 d at 25 °C. On MEA surface luteous, reverse ochreous; on PDA surface and reverse ochreous; on OA sur- face ochreous.

Typus. NETHERLANDS, Gelderland Province, Wageningen, Belmonte Botanical Garden, on Spiraea japonica (Rosaceae), 28 July 2020, P.W. Crous, HPC 3291 (holotype CBS H-24865, culture ex-type CPC 39565 = CBS 148332, ITS and LSU sequences GenBank OK664715.1 and OK663754.1).

Notes — Although morphologically resembling members of the genus Chalara, the newly described species cannot be accommodated in any of the known Chalara species. Members of the genus Chalara with 1-septate conidia either have conidia with rounded ends, or a rounded apex and truncate base (Nag Raj & Kendrick 1976, McKenzie et al. 2002). However, N. spiraeae is distinct in having conidia with both ends being truncate. Furthermore, the distinct phylogenetic position also supports the taxonomical novelty. The present genus, Neocha­ lara, appears to be allied to orbiliopsis-like taxa, although data to support this potential link presently remains inconclusive.