Cytospora piceicola Ilyukhin & Markovsk., 2025

Ilyukhin, Evgeny, Chen, Yanpeng, Markovskaja, Svetlana, Shami, Ashwag & Maharachchikumbura, Sajeewa S. N., 2025, Comprehensive genome analysis of two Cytospora (Cytosporaceae, Diaporthales) species associated with canker disease of spruce: C. piceae and C. piceicola sp. nov., MycoKeys 117, pp. 89-119 : 89-119

Cytospora piceicola Ilyukhin & Markovsk. sp. nov.

Fig. 4

Etymology.

The name refers to the host genus, Picea , from which the fungus was first isolated.

Holotype.

Canada • Ontario, Lincoln , 43°06'39.0"N, 79°19'15.4"W, isolated from cankered wood (branches) of Picea glauca , April 2020, E. Ilyukhin (holotype BILAS 51884 , ex-holotype living culture BILAS 51886 = EI-20, isotype DAOM 985024 , DAOMC 256985 ).

Description.

Sexual morph: not observed in culture. Asexual morph: Conidiomata appearing after 25 days of incubation on MEA, rare, pycnidial, solitary, globose to subglobose, dark grey to black when dry, with few ovoid locules, (610 –) 824–1071 (– 1380) μm diam. Conidiophores micronematous, hyaline, smooth-walled, reduced to unbranched conidiogenous cells. Conidiogenous cells enteroblastic, phialidic, lageniform, or ampulliform (7.5 –) 8.8–10.6 (– 13.0) × (1.0 –) 1.3–1.7 (– 2.0) μm. Conidia abundant, relatively small, single, hyaline, aseptate, slightly curved, allantoid, thin-walled (3.5 –) 3.8–4.9 (– 5.5) × (1.0 –) 0.8–1.3 (– 1.5) μm.

Culture characteristics.

Colonies on MEA white to light brown with short aerial mycelium tufts in the center, becoming darker with age, relatively slow-growing (28 mm in diameter) after 7 days of incubation. Hyphae hyaline, smooth, branched, and septate.

Notes.

Based on ITS sequence data, C. piceicola is 99 % similar to C. globosa MFLU : 16-2054 (554 / 559, 3 gaps) and C. pinastri CBS 113.81 (540 / 545, 0 gaps). But combined multi-gene phylogenetic analysis clearly distinguished C. piceicola from these two species (ML / BI = 95 / -). The new species, C. piceicola , differs from C. globosa (4–6.5 × 1–2 µm) and C. pinastri (4–7 × 1–1.3 μm) by having shorter conidia and clearly lageniform or ampulliform conidiogenous cells ( Hayova and Minter 2013; Li et al. 2020). The culture characteristics cannot be used for species discrimination as they are either unavailable ( C. pinastri ) or different media has been used ( C. globosa ). Thus, C. piceicola is considered a novel species based on both molecular data and morphological characteristics.

Figures

Figure 4. Asexual morph of C. piceicola A isolation source (cankered branches of P. glauca) B adverse and reverse view of seven-day-old culture on MEA C pycnidia (with locules) on the surface of the colony after 25 days of incubation D conidiogenous cells E conidia. Scale bars: 1 mm (C); 5 μm (D, E).