Allocucurbitaria botulisporaValenz.-Lopez, Stchigel, Guarro & Cano, in Valenzuela-Lopez, Cano-Lira, Guarro, Sutton, Wiederhold, Crous & Stchigel, Stud. Mycol.90: 52 (2017)

Index Fungorum number: IF 819770; MycoBank number: MB 819770, Facesoffungi number: FoF 09660

Etymology From Latin botulus-, sausage, and –spora, spores, due to the shape of the conidia.

Description – Hyphae pale brown, smooth- and thin-walled, septate, 1.5–2.5 μm wide. Conidiomata pycnidial, brown, confluent, superficial (OA), glabrous, subglobose to ovoid, 60–160 × 60–120 μm diam, with 1–2 papillate ostiolar necks; pycnidial wall of textura angularis, 2–4 layered, 10–30 μm thick, composed of pale brown to brown, flattened polygonal cells of 3–10 μm diam. Conidiogenous cells phialidic, hyaline, smooth-walled, ampulliform, 5–8 × 2–2.5 μm. Conidia aseptate, hyaline, smooth- and thin-walled, cylindrical to allantoid, 3–5 × 1–1.5 μm, guttulate. (Jaklitsch et al. 2018)

Culture characteristics – Colonies on OA reaching 26–29 mm diam after 7 d at 25 ± 1 °C, flattened, greyish yellow (M. 4C6); reverse olive brown (M. 4D5). Colonies on MEA reaching 22 mm after 7 d at 25 ± 1 °C, slightly floccose, yellowish white (M. 4A2); reverse pale orange (M. 5A3) to deep orange (M. 5A8). NaOH spot test negative. Crystals absent. Optimal temperature of growth and sporulation 25 °C; minimum temperature of growth 15 °C; maximum temperature of growth 37 °C.

Material examined –USA, from human scab on leg, 2009, D.A. Sutton (holotype CBS H-23028, ex-holotype living cultures CBS 142452 = UTHSC DI16-273 = FMR 13764).

Notes – The strain CBS 142452 (= UTHSC DI16-273) was originally assigned to Pyrenochaeta (Valenzuela-Lopez et al. 2016). Morphologically, this strain displays a morphology more similar to phoma-like taxa (with glabrous pycnidia) than to species of Pyrenochaeta (because of its setose conidiomata). In our phylogenetic analysis, this fungus was placed in an uncertain taxonomic position within Cucurbitariaceae. Therefore, we proposed to accommodate CBS 142452 as a new species of the new genus Allocucurbitaria.

Figure 1 – Allocucurbitaria botulispora (CBS 142452). A, B. Colony on OA (front and reverse). C, D. Colony on MEA (front and reverse). E. Pycnidia forming on OA. F. Pycnidium. G. Conidiophores. H. Conidia. Scale bars: F = 50 μm. G, H = 10 μm.