Cytospora diatrypelloidea G.C. Adams & M.J. Wingf., in Adams, Wingfield, Common & Roux, Stud. Mycol. 52: 121 (2005)

Index Fungorum number: IF 500223; MycoBank number: MB 500223; Facesoffungi number: FoF 15305; Figs. 1, 2

Associated with leaf spots and necrosis, debris and dead branches of Myrtaceae species. Sexual morph: not observed. Asexual morph: Conidiomata pycnidial, aggregated and abundant with pale yellow cirrhi in ten-day-old cultures. Conidiophores hyaline, branched or unbranched. Conidiogenous cells phialidic, narrowing at the apices, 6.9–8.9–9.8 × 1.5–1.7–2.0 µm (n = 20). Conidia hyaline, aseptate, allantoid, eguttulate, 4.9–5.4–8.9 × 1.0–1.5–2.5 µm (n = 20).

Culture characteristics – Colonies on PDA at 21 °C and incubated under black light were slow growing, 10–12 mm in diameter after three days and 15–25 mm in diameter after seven days; with uneven margin expansion, raised, pale olive-gray to olive-black on the surface with a greenish irregular margin, olive-black on reverse.

Material examined – NEW ZEALAND, from leaf spots on Eucalyptus leucoxylon, August 2016, R. Thangavel, PHEL T16_01761A. Culture stored at the International Collection of Microorganisms from Plants (ICMP24058); Pauatahanui, from leaf necrosis on Eucalyptus sp., April 2018, R. Thangavel, PHEL T18_01389; Lower Hutt, from leaf necrosis on Corymbia ficifolia, September 2020, K. Hofer, PHEL T20_02185; and Auckland, from leaf spot on Eucalyptus nitens, December 2020, R. Thangavel, PHEL T20_03057.

Known hosts and distribution – AUSTRALIA, on Eucalyptus sp. (Summerell et al. 2006) and E. globulus (Adams et al. 2004); NEW ZEALAND, on Eucalyptus sp., E. nitens, E. leucoxylon, and Corymbia ficifolia (this study).

GenBank – OR807322, PP068838, PP068839, PP068840 (ITS), OR808084 (LSU), OR814105 (act), OR814109 (rpb2), OR814113 (tef1), OR814117 (tub2).

Notes – Multi-gene phylogeny using combined ITS, LSU, rpb2 and act sequences demonstrated that our isolate and the type strain of C. diatrypelloidea (CMW8549) clustered into a well-supported clade (Fig. 1). There is limited sequence data available for the type strain of C. diatrypelloidea, but only a single nucleotide difference in the ITS region was found to our isolate. Additional DNA regions were sequenced in this study to provide additional reference sequence data. Since the first find of C. diatrypelloidea in New Zealand in 2016, the fungus has been associated with leaf necrosis on Eucalyptus sp., leaf necrosis on Corymbia ficifolia and leaf spot on Eucalyptus nitens. While Australian records of C. diatrypelloidea are from dead branches (Adams et al. 2004) and leaf litter (Summerell et al. 2006), the New Zealand detections are from fresh symptomatic leaf material indicating that C. diatrypelloidea could be plant pathogenic. However, further studies are needed to confirm pathogenicity of C. diatrypelloidea. This is the first published record of C. diatrypelloidea from New Zealand and first report from a non-Eucalyptus host. Corymbia ficifolia belongs to Myrtaceae, suggesting that C. diatrypelloidea could be present in a wider range of hosts in Australia and New Zealand, where this plant family is wide-spread and species-rich.

Figure 1 – Maximum likelihood (GTR + G + I) tree illustrating the phylogenetic placement of the Cytospora species discussed in-text (in bold) within the genus. This phylogenetic tree is based on the alignment of concatenated ITS, act and rpb2 sequences. Branches are labelled with bootstrap prob abilities = 70% across 1,000 bootstrapping replicates, and type specimens are denoted by a superscript “T”. Diaporthe vaccinii CBS 160.32 was used as an outgroup.

Figure 2 – Cytospora diatrypelloidea (ICMP24058). a Colony on PDA media after 7 days. b Close up of colony edge. c Conidiomata on colony surface with pale yellow cirrhi. d, e Conidiogenous cells. f, g Conidia. Scale bars = 10 µm.