Fusarium queenslandicum T.B. Potter, A.H. Sparks, Vaghefi & R.G. Shivas, sp. nov.

Index Fungorum number: IF 837495; MycoBank number: MB 837495; Facesoffungi number: FoF 09579; Fig. 1

Etymology. The name refers to the State of Queensland, from where this fungus was collected.

Holotype: – BRIP 70769a

Saprobic on dead stalk of Sorghum bicolor. Sexual morph Undetermined. Asexual Morph Conidiophores abundant on aerial mycelium, unbranched, lateral or terminal. Conidiogenous cells monophialides, subcylindrical. Microconidia in false heads on aerial mycelium, 4–25×3–4.5 µm, narrowly ellipsoidal or reniform, hyaline, aseptate. Sporodochia and macroconidia not seen. Chlamydospores 7–13×7–9 µm, abundant, globose to ellipsoidal, intercalary or terminal, single or in pairs, rough-walled.

Culture characteristics – Colonies on PDA reaching 90 mm at 24 °C after 28 d, surface appressed with velvety cream patches of aerial mycelium up to 1 cm diam., subhyaline on the agar; reverse pale buff; on SNA with sparse aerial mycelium, cream becoming pale violet in the central part; sporulation abundant on PDA, SNA, WA and carnation leaf pieces.

Material examined – AUSTRALIA, Goondiwindi, on dead stalk of Sorghum bicolor, 19 February 2018, N. Vaghefi, BRIP 70769a (holotype), includes an ex-type living culture.

GenBank numbers – RPB1 = MW038832, RPB2 = MW038833, TEF1-α = MW038834, TUB2=MW403138.

Notes – Fusarium queenslandicum belongs to the F. oxysporum species complex (Lombard et al. 2019a) based on sequence comparisons of the RPB1, RPB2, TEF1-α and TUB2 loci with those available in the Fusarium MLST database (http://www.cbs.knaw.nl/fusarium). The TEF1-α sequence of F. queenslandicum was identical to a culture (CBS 412.90 = NRRL 36464) collected from tomato in Israel that was identified as F. languescens. A pairwise comparison revealed 10 nucleotide variations between the TEF1-α sequence of F. queenslandicum and that of the extype culture of F. languescens (CBS 64578=NRRL 36531). The four-locus phylogeny based on sequences of CAL, RPB2, TEF1-α, and TUB2 clearly separated F. queenslandicum from F. languescens and other species within the FOSC (Fig. 2). Fusarium queenslandicum was isolated from an asymptomatic stalk of cultivated Sorghum bicolor (Fig. 1).

Figure 1 – Fusarium queenslandicum (BRIP 70769a, holotype). a, b Culture on PDA from surface and reverse. c Conidiophores with false heads. d Microconidia. e Chlamydospores. Scale bars: a, b=1 cm, c–e=10 µm

Figure 2 – Phylogram generated from Bayesian analysis based on combined CAL, RPB2, TEF1-α, and TUB2 sequence data representing Fusarium oxysporum species complex and related taxa. The second measure of branch support was obtained through Maximum Likelihood (ML) analysis of the same alignment using RAxML v. 8 (Stamatakis 2014) based on the GTR substitution model with gamma-distribution rate variation for each partition. Reference sequence were obtained from Lombard et al. (2019a) and Maryani et al. (2019). The tree is rooted to Fusarium foetens (CBS 120665). The analysis was performed using MrBayes v. 3.2.4 (Ronquist et al. 2012) based on the K80, K80+G, HKY+G, and SYM+I+G nucleotide substitution models selected for CAL, RPB2, TEF1-α, and TUB2, respectively, using PAUP v. 4.0 (Swofford 2003) and MrModeltest v. 2.3. (Nylander 2009). Maximum likelihood bootstrap support values (MLBS) greater than 80% are placed above the nodes and Bayesian posterior probabilities (BYPP) equal to or greater than 0.95.  Branches with BYPP=1.00 and MLBS=100% are thickened. Scale bar indicates the number of substitutions per nucleotide. Ex-type strains are in bold and newly sequence is in blue