Pseudohumicola glauca (De Bert.) Sastoque, Stchigel & Cano, 2025

Sastoque, A. P., Cano-Lira, J. F. & Stchigel, A. M., 2025, Soil ascomycetes from Spain. XIV. The Chaetomiaceae of La Palma (Canary Islands), Persoonia 54 (1), pp. 93-117 : 108-109

Pseudohumicola glauca (De Bert.) Sastoque, Stchigel & Cano , comb. nov. MycoBank MB 853458. Fig. 9 .

Basionym: Humicola glauca De Bert., Canad. J. Bot. 54: 2757. 1976.

Typus: Italy, nematode-infested soil, 1970, coll. and isol. M. de Bertoldi (lectotype designated here CBS H-7238, MBT 10026348, culture ex-type CBS 462.76 = MUCL 19429 = FMR 19938 ) .

On potato carrot agar after 2 wk at 25 °C: Mycelium composed of hyaline, septate, branched, smooth- and thin-walled, 1–2 μm wide hyphae. Conidiophores absent. Conidiogenous cells integrated to the hyphae. Conidia holoblastic, unicellular, solitary, sessile or on short conical denticles or on short side branches ( Fig. 9E ), less frequently in short chains or forming few-celled clusters ( Fig. 9F ), or intercalary (holothallic; Fig. 9F ), smooth- and thick-walled, covered by a mucilaginous and dark brown substance, becoming verrucose to reticulate when old, pale olivaceous brown to brown, globose, subglobose, oblate, ellipsoid, obovoid, piriform, occasionally ovoid or cylindric, (4–)7–8(–9) × (4–)8–10(–15) μm ( Fig. 9E, F ). Acremonium-like synasexual morph and sexual morph not observed.

Culture characteristics (after 7 d at 25 ° C): Colonies on PCA 30–31 mm diam., flat and circular; margins filamentous and regular; surface chocolate (6F4) at the centre, with a white (6A1) aerial mycelium, margins yellowish white (4A2); soluble pigment absent; reverse dark brown (6F2) at the centre, surrounded by a chocolate (6F4) halo, margins yellowish-white (4A2). Colonies on OA 37–39 mm diam., flat and circular and expansive; margins filamentous and regular; surface dark brown (5F8), with a floccose white (4B1) aerial mycelium at the centre, margins cream (4B3); soluble pigment absent; reverse dark brown (5F8) at the centre, marble-white (5B2) at the margins. Colonies on CMA 31–34 mm diam., flat and circular; margins filamentous and regular; surface dark brown (5F5) at the centre, with a scarce white (5A1) aerial mycelium, margins yellowish white (4A2) to uncoloured; soluble pigment absent; reverse similar in colour than the surface. Colonies on MEA 35–36 mm diam., flat and circular; margins filamentous and regular; surface brown (5E5) with a floccose white (8A1) aerial mycelium at the centre, margins yellowish white (4A2); reverse cream (4A3) but brown (5E4) at the centre. Culture iconography after 2 wk of incubation on PCA, OA, CMA and MEA ( Fig. 9A–D , respectively). Minimum, optimum and maximum temperature of growth on PDA after 7 d: 15 °C, 30 °C and 37 °C, respectively.

Additional material examined: Spain, Canary Islands, La Palma, Fuencaliente (Los Canarios), isolated from Teneguía volcano soil, 15 Jul. 2008, coll. M. Calduch & A.M. Stchigel, isol. A.P. Sastoque (culture FMR 18982 = CBS 150904 ) .

Notes: Humicola glauca CBS 462.76 was placed close to P. semispiralis CBS 723.97 ( Fig. 1 ), and consequently transferred to the genus Pseudohumicola . Pseudohumicola glauca differs from Pseudohumicola semispiralis by lacking a sexual morph and by the size and shape of conidia [globose, subglobose, oblate, ellipsoid, obovoid, piriform, occasionally ovoid or cylindric, (4–)7–8(–9) × (4–)8–10(–15) μm in P. glauca vs globose to oblate, sometimes ovoid, (8.5–)9–11 μm diam. in P. semispiralis ] ( Udagawa & Cain 1969, Wang et al. 2019b).

Figures

Fig. 9. Pseudohumicola glauca CBS 462.76. A–D. Colonies on PCA, OA, CMA, MEA (2-wk-old; 25 °C; surface, left; reverse, right). E. Conidia single cell, aseptate, sessile or on short denticles (DIC). F. Conidia solitary or on short chains (PC). Scale bars = 10 μm.

Fig. 1. Maximum likelihood of the tree obtained from the concatenated ITS-LSU-rpb2-tub2 (3215 bp) alignment of the nucleotide sequences from our strains and those retrieved from the GenBank. Bayesian posterior probabilities (PP) ≥ 0.95 and the RAxML bootstrap support values (BS) ≥ 70 % are presented at the nodes (PP/BS). Thickened branches indicate full support (PP = 1 and BS = 100 %). The new species and combinations are indicated in bold. T represents the ex-type strain of the species. NT represents the ex-neotype strain of the species.