Pseudofusicoccum kimberleyense Pavlic, T.I. Burgess & M.J. Wingf., Mycologia 100(6), 857 (2008).
Index Fungorum number: IF 512049, MycoBank number: MB 512049;
Saprobic on Dipterocarpus alatus woody litter. Sexual morph: Ascomata 218–279 μm diam., 160–320 μm high (x̅= 250 × 227 µm, n = 5), uniloculate, appearing as black spots on host bark surface, subglobose to globose, solitary or scattered, immersed to semi-immersed, coriaceous. Peridium 35.5–60(–62) μm wide (x̅= 47 μm, n = 35), two strata composed of cells of textura angularis, outer stratum of dark brown to black thick-walled cells combining at the outside with the host tissues, inner stratum lightly pigmented to hyaline. Hamathecium comprises hyaline pseudoparaphyses arising from a basal stromatal tissue and shorter than asci. Asci (70–)80–140(– 155) × 19–25(–28) μm (x̅= 105 × 22 μm, n = 30), 8-spored, bitunicate, fissitunicate, with thick outer wall, inner wall raised in center, clavate to cylindric-clavate, straight to curved, with short, knob-like pedicel, apically rounded with a moderately distinct ocular chamber. Ascospores 19.5– 30 × 10.5–14.5 μm (x̅= 24 × 12 μm, n = 35), biseriate, overlapping, ovoid to clavate, wide and rounded at apex, hyaline, aseptate, smooth-walled, straight, finely guttulate surrounded by a thin mucilaginous sheath. Asexual morph: Undetermined.
Culture characteristics – Ascospores germinated on PDA within 24 h, and a germ tube emerged from one end cell. Colonies reached 90 mm diam. after 10 days at room temperature (25–28 °C), curled, with umbonate elevation, dense, fluffy appearance, narrow towards the margin, non-pigmented, at the upper surface radiating from brown to grey outwardly, and from the reverse, opaque black.
Material examined – Thailand, Chiang Rai Province, Doi Tung National Park, on dead wood of Dipterocarpus alatus (Dipterocarpaceae), 26 March 2022, N. Afshari, 2C1T1R2a (MFLU 24-0398); living culture MFLUCC 24-0527.
GenBank numbers – ITS: PQ800230, tef1-α: PV138146, tub2: PX753045.
Known hosts – Adansonia gibbosa, Acacia synchronica, Eucalyptus sp., and Ficus opposita (Pavlic et al. 2008), Carya illinoinensis (Rolim et al. 2020), Acacia mangium, Pinus massoniana, and Eucalyptus sp. (Li et al. 2023b), Dipterocarpus alatus (this study).
Known distribution – Australia (Pavlic et al. 2008), Brazil (Rolim et al. 2020), China (Li et al. 2023b), Thailand (this study).
Notes – Based on BLASTn search of ITS– tef1-α–tub2 sequences in GenBank, it was found that our isolate shows high similarity to P. kimberleyense (ex-type strain, CBS 122058) with 99.52%, 100%, and 100% similarity, respectively. Additionally, in the phylogenetic tree, P. kimberleyense (MFLUCC 24-0527) is closely related to CBS 122058 and CBS 122059 strains, showing 81% ML/ 1.0 PP support values (Fig. 9). Our strain was isolated from decaying wood of Dipterocarpus alatus in Thailand, while the ex-type strain was collected on dying branches of Adansonia gibbosa, Acacia synchronica, Eucalyptus sp., and Ficus opposita in Western Australia (Pavlic et al. 2008). It has also been isolated in Brazil and China (Rolim et al. 2020, Li et al. 2023b). According to the multilocus phylogenetic results of ITS, tef1-α, and tub2 DNA matrix, we report our strain as the first recorded sexual morph of P. kimberleyense. This is also the first report of P. kimberleyense from Dipterocarpus alatus in Thailand.
Figure 1 – Phylogram generated from maximum likelihood analysis based on the combined ITS, tef1-α, and tub2 sequence data of Pseudofusicoccum. Tree topology of the maximum likelihood analysis is similar to the Bayesian analysis. Twenty-one strains are included in the combined analyses, which comprised 1,270 characters (ITS = 520, tef1-α = 298, and tub2 = 452) in the combined dataset. The best RAxML tree with a final optimization likelihood value of – 3124.719755 is presented. The matrix had 215 distinct alignment patterns, with 12.38% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.197834, C = 0.311332, G = 0.265322, T = 0.225512; substitution rates AC = 0.615930, AG = 2.767036, AT = 0.769769, CG = 0.593671, CT = 5.579173, GT = 1.000000; gamma distribution shape parameter α = 0.210720. In the Bayesian analysis, average standard deviation of split frequencies at the end of 2,000,000 MCMC generations was calculated as 0.004506. The evolutionary models TIM3ef+I, 4807 TrN+G, and TIM3+I were applied to ITS, tef1-α, and tub2 sequence data, respectively, in BI analysis. Bootstrap support values for maximum likelihood greater than or equal to 80% and Bayesian posterior probabilities greater than or equal to 0.90 are given above the nodes. The strain codes are noted after the species names. The tree is rooted with Lasiodiplodia pseudotheobromae (CPC 22758) and L. theobromae (MFLUCC 12-0293). Ex-type strains are in bold. The isolates generated in this study are indicated in bold and blue.
Figure 2 – Sexual morph of Pseudofusicoccum kimberleyense (MFLU 24-0398, a new host record). a, b Close-up of ascomata on Dipterocarpus alatus woody litter. c Vertical section through ascoma. d Section of peridium. e–f Hamathecium and asci. g–k Asci. l Ascus in Melzer’s reagent. m Ocular chamber in Melzer’s reagent. n–s Ascospores. t A germinated ascospore. u, v Colony on PDA from above and reverse. Scale bars: a = 1 mm, b = 500 μm, c = 50 μm, d–m, t = 20 μm, n–s = 10 μm.