Canariomyces asexualis 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 : 99

Canariomyces asexualis Sastoque, Stchigel & Cano , sp. nov. MycoBank MB 847933. Fig. 3 .

Etymology: From Latin a -, without, - sexus -, sex, and - alis, quality of, because the fungus lacks of sexual reproduction.

Typus: Spain, Canary Islands, La Palma, Fuencaliente (Los Canarios), from soil of Teneguía volcano, 15 Jul. 2008, coll. M. Calduch & A.M. Stchigel, isol. A.P. Sastoque (holotype CBS H-25249, culture ex-type FMR 19389 = CBS 149966 ) .

On oatmeal agar after 4 wk at 25 °C: Mycelium abundant, mostly aerial, septate, branching, smooth- and thin-walled hyphae when hyaline to subhyaline but granulose when pigmented, 1–4.5 μm wide, often coiled. Conidiogenous cells integrated to the hyphae, monoblastic, producing sessile conidia. Conidia 1-celled, solitary, arising laterally on the hyphae, subhyaline to olivaceous brown, smooth- and thin-walled, obovoid, pyriform, broadly fusiform, subglobose, ellipsoidal, clavate or heart-shaped, 3–6 × 2.5–4 μm ( Fig. 3E, F ). Sexual morph not observed.

Culture characteristics (after 7 d at 25 ° C): Colonies on PCA 35–36 mm diam., flat and circular; margin filamentous; surface natural (4B3) without aerial hyphae and with grey (3E1) radiate superficial mycelium; soluble pigment absent; reverse beige (4B3) and pale yellow in the centre (4A3). Colonies on OA 39–40 mm diam., flat, circular, and expansive; margin filamentous; surface beige (4B3) to golden (4C6) without aerial mycelium; soluble pigment absent; reverse uncoloured to golden (4C6). Colonies on CMA 22–23 mm diam., flat, circular, and expansive; margin filamentous; surface without aerial mycelium, champagne (4B4) in the central area with radiate soot brown (5F5) superficial mycelium and uncoloured margins; soluble pigment absent; reverse sepia (5E4). Colonies on MEA 34–35 mm diam., flat and circular; margin entire; surface with hair brown (5F2) superficial mycelium radiated, sparse floccose white (5A1) aerial mycelium just in the centre and natural (4B3) margins; soluble pigment absent; reverse like surface. Culture iconography after 4 wk of incubation on PCA, OA, CMA and MEA ( Fig. 3A–D , respectively). Minimum, optimum and maximum temperature of growth on PDA after 7 d: 12 °C, 35 °C and 40 °C, respectively.

Notes: Canariomyces asexualis was placed in a fully supported terminal clade together with Canariomyces microsporus CBS 276.74 and CBS 161.80, but in a separate branch as a distinct species ( Fig. 1 ). Canariomyces asexualis lacks a sexual morph and differs morphologically from Canariomyces microsporus in the size and shape of conidia ( Can. microsporus produces obovoid to clavate conidia, measuring 4–10.5 × 2–3.5 μm, whereas Can. asexualis forms obovoid, pyriform, broadly fusiform, subglobose, ellipsoidal, clavate, or heart-shaped conidia, measuring 3–6 × 2.5–4 μm) ( Mouchacca 1973, Wang et al. 2019a).

Figures

Fig. 3. Canariomyces asexualis CBS 149966. A–D. Colonies on PCA, OA, CMA, MEA (4-wk-old; 25 °C; surface, left; reverse, right). E, F. Conidia sessile, 1-celled, solitary and widely variable in shape. 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.