Pseudohumicola variispora Sastoque, Cano & Stchigel, 2025

Pseudohumicola variispora Sastoque, Cano & Stchigel , sp. nov. MycoBank MB 847751. Fig. 11 View Fig .

Etymology: From Latin variis -, diverse, and - spora, spore, due to the morphological variability of the conidia.

Typus: Spain, Canary Islands, La Palma, Fuencaliente (Los Canarios), isolated from soil of Teneguía volcano, 15 Jul. 2008, coll. M. Calduch & A.M. Stchigel, isol. A.P. Sastoque (holotype CBS H-25244, culture ex-type FMR 18822 View Materials = CBS 149960 View Materials ) .

On potato carrot agar after 4 wk at 25 °C: Mycelium abundant, composed of hyaline, septate, branched, smooth- and thin-walled, 0.5–3 μm wide hyphae. Conidiophores undifferentiated. Conidiogenous cells integrated to the vegetative hypha. Conidia mostly holoblastic and 1-celled, solitary, sessile, on short conical denticles or on short side branches from the hyphae ( Fig. 11E View Fig ), smooth- and thick-walled, covered by mucilaginous and dark brown sheath, becoming verruculose when old ( Fig. 11E, J View Fig ), rarely 2−3-celled, sometimes generating secondary conidia to form short chains (2−3-celled) ( Fig. 11E–H View Fig ), occasionally intercalary (holothallic), then 1−2-celled ( Fig. 11I View Fig ), brown, globose, subglobose, oblate, ellipsoid, obovoid, piriform, occasionally ovoid or cylindric, (3–)7–8(–9) × (4–)7–10(–15) μm, mostly truncated at the base or at both ends (when intercalary), secession rhexolytic ( Fig. 11E–J View Fig ). Acremonium-like synasexual morph and sexual morph not observed.

Culture characteristics (after 7 d at 25 ° C): Colonies on PCA 9–12 mm diam., circular and flat; margin lobulated to irregular; surface showing white (4A1) aerial mycelium in the central area, surrounded by a black (4F1) superficial area and with cream (4B3) margins; soluble pigment absent; reverse black (4F2) to smoke brown (4F1) with yellowish white margins (4A2). Colonies on OA 28–30 mm diam., flat, circular and expansive; margin entire and regular; surface dry, opaque, with floccose white (6A1) aerial hyphae only in the central area, margins cream (4A3) without aerial hyphae and chocolate (6F4) short, radiated lines at the bottom; soluble pigment absent; reverse yellowish brown (5F8) in the centre with short radiated lines and margins yellowish-white (3A2). Colonies on CMA 11–14 mm diam., circular and flat; margin entire and regular; surface canary yellow (2B7) with scarce greyish white (4B1) aerial hyphae in the centre, margins uncoloured; soluble pigment absent; reverse greyish yellow (2B5). Colonies on MEA 17–18 mm diam., flat and circular; margin filamentous and undulated; surface light yellow (3A5) in the centre to cream (4A3) without aerial hyphae; soluble pigment absent; reverse butter-yellow (4A5) in the centre and margins cream (4A3). Culture iconography after 2 wk of incubation on PCA, OA, CMA and MEA ( Fig. 11A–D View Fig , respectively). Minimum, optimum and maximum temperature of growth on PDA after 7 d: 12 °C, 30 °C and 40 °C, respectively.

Notes: Pseudohumicola variispora was placed in a fully supported clade close to P. lutea COAD 3127 and P. debertoldii CBS 460.76, but as a different species in a basal branch ( Fig. 1 View Fig ). Pseudohumicola variispora differs from P. lutea by presence of 2−3-celled sessile conidia and 1−2-celled intercalary conidia, and by the formation of thick-walled verrucose conidia in P. variispora , while P. lutea does not produce intercalary conidia, the conidia are unicellular and thick but smooth-walled ( Oliveira et al. 2023). Pseudohumicola variispora differs from P. debertoldii in having lateral, terminal and intercalary 2−3-celled conidia covered by mucilaginous and dark brown sheath, and sometimes produces secondary conidia to form short chains (2−3-celled) and does not present an acremonium-like asexual morph.