Coniella eucalyptorum (Crous & M.J. Wingf.) L.V. Alvarez & Crous, Stud. Mycol. 85: 15 (2016)

Index Fungorum Registration Identifier 817817, Fig. 2

Basionym: Pilidiella eucalyptorum Crous & M.J. Wingf., in Van Niekerk, Groenewald, Verkley, Fourie, Wingfield & Crous, (2004).

Pathogenic on leaves of E. camaldulensis . Sexual morph: Undetermined. Asexual morph: Conidiomata 80−140 μm long, 150−200 μm in diameter (n= 15), solitary or aggregated, globose, brown, and dark brown to black from the top. Conidioma wall consisting of 2–3 layers of hyaline textura prismatica and 4−5 layers of brown textura angularis cells. Conidiogenous cells 12–15 × 1–2 μm (x̄ = 13 × 2 μm, n = 20), annellidic, narrowing at the tip, smooth and hyaline. Conidia 10−13 × 3−6 μm (x̄ = 12 × 5 μm, n = 30), hyaline to pale brown, becoming dark brown at maturity, smooth, broadly ellipsoidal, both sides gradually tapering, smooth-walled, and multi-guttulate with one or two prominent guttules.

Culture characteristics: Colony on PDA reaching 25 mm diameter after seven days at 25 °C, colony circular, margin wavy, flat, velvety appearance, colony from above: pale pink to brown; reverse: light brown to dark brown.

Material examined: Sri Lanka, North Central Province, Polonnaruwa District, Aralaganwila, (Latitude 7.293889 Longitude 81.2109594) on leaves of E. camaldulensis, 5 th of May 2022, Rashika S. Brahmanage, RB-LP31, (NIFSCC-RB-LP31, UOCCC-RB-LP31 )

GenBank accession numbers: ITS = OR141147, LSU = OR143784, tef1-α = OR461287

Notes: Based on the morphological characteristics, our strain (NIFSMC-RB-LP31) is similar to the holotype of Coniella eucalyptorum (CBS 112640) collected from the leaves of Eucalyptus grandis × E. tereticornis hybrid (Alvarez et al. 2016). According to multi-gene phylogeny (ITS, LSU, and tef1-α), our strain (NIFSMC-RB-LP31) clustered with other strains of C. eucalyptorum (CBS 111023, CBS 112640, CBS 114134, and MFLU 17-0675) with 100% ML and 1.00 PP bootstrap support (Fig. 1). When comparing the ITS, LSU, and tef1-α gene regions, no base pair (0%) differences were observed between our strain (NIFSMC-RB-LP31) and the holotype of C. eucalyptorum (CBS 112640). Coniella eucalyptorum was previously recorded in Australia, Brazil, Chile, Indonesia, Malaysia, Mexico, Thailand, Venezuela, and Vietnam (Hyde et al. 2020). Therefore, we identified our fungal collection as the first geographical record from Sri Lanka.

Pathogenicity assay

Results of the pathogenicity test showed that the RB-LP31 strain (identified as C. eucalyptorum) can cause disease on only wounded host leaves. The initial symptoms were seen on wounded leaves after two to three days of inoculations with mycelial plugs (Fig. 3, e 1 – e 4). Small light-brown to brown lesions emerged at the inoculation site of the leaves. Subsequently, these lesions rapidly enlarged (diameter 2 – 5.5 cm) and transformed into brown to dark brown lesions after five days of inoculation. Symptoms continuously spread, and sparse white mycelia appeared on the lesions three days post-inoculation and subsequently spread throughout the host leaf. Initial symptoms were seen on wounded leaves treated with spore suspensions of C. eucalyptorum after 10–12 days of inoculation (Fig. 3, a 1 – a 4), and 1–3 cm lesions appeared after 16 days of inoculation. Non-wounded leaves inoculated with both spore suspensions and mycelial plugs showed no symptoms even after 16 days of inoculation (Fig. 3, b and f), similar to the negative control treatments (Fig. 3, c, d, g, and h). Based on the morphological characteristics, we identified the re-isolated fungus as C. eucalyptorum .