Dictyosporium pandanicola Tibpromma & K.D. Hyde, in Tibpromma et al., Fungal Diversity: 93: 20 (2018)

Index Fungorum number: IF 554481; MycoBank number: MB 554481; Facesoffungi number: FoF 04491; Fig. 1

Saprobic on submerged decaying wood. Sexual morph Undetermined. Asexual morph Colonies, punctiform, sporodochial, scattered, dark brown to black, glistening. Mycelium mostly immersed, composed of smooth, septate, branched, hyaline to pale brown hyphae. Conidiomata sporodochia on the natural substrate in small groups, dark brown. Conidiophores 10–20×2.5–3 µm, micronematous, mononematous, cylindrical, subhyaline to pale brown, septate, smooth, sometimes reduced to conidiogenous cell. Conidiogenous cells holoblastic, integrated, indeterminate, subhyaline to pale brown. Conidia 40–48×20–25 µm (x̅=44×23 µm, n=35), solitary, oval to ellipsoid, cheiroid, smooth-walled, consisting of 5–6 arms, 9–13-euseptate in each arm, with a basal connecting cell, yellow–brown to brown with age, sometimes with a hyaline, globose, apical appendage.

Culture characters – Conidia germinated on PDA within 24 h. Colonies on PDA reaching 2.5–3.5 cm diam., after 4 weeks at room temperature, colonies irregular, medium dense, white to yellow in top view. In reverse, yellow in the middle and white at the margin.

Material examined – THAILAND, Surat Thani Province, Sai Daeng, on decaying wood submerged in a small river, 2 October 2017, Z.L. Luo, B77 (MFLU 20-0425, new record), living culture, MFLUCC 18-0331.

GenBank numbers – ITS=MZ490792, LSU=MZ490775, TEF1-α=MZ501208.

Notes – In the phylogenetic analysis (Fig. 2), the new isolate of Dictyosporium pandanicola (MFLUCC 18-0331) clusters with Di. pandanicola (MFLU 16-1886) with high bootstrap support (100% MLBS, 0.97 BYPP). In addition, there is only 1 base pair difference observed in the ITS region between these two strains. These two strains share some similar characters such as micronematous conidiophores, holoblastic conidiogenous cells and oval to ellipsoid, cheiroid, yellow–brown to brown conidia with 5–6 arms and overlapping conidia size (40–48×20–25 μm vs. 30–50×15–33 µm). However, conidia of MFLUCC 18-0331 sometimes have a hyaline, globose, apical appendage. While conidia of MFLU 16-1886 lack apical appendages. This difference in appendages may be because of the different habitats. MFLU 16-1886 was collected form a terrestrial habitat on Pandanus, while MFLUCC 18-0331 was collected from a freshwater habitat on submerged wood. Based on both morphology and molecular data, we consider the isolate MFLUCC 18-0331 and Di. pandanicola to be conspecific.

Figure 1 – Dictyosporium pandanicola (MFLU 20-0425, new record). a–c Colonies on wood. d–h Conidiophores, conidiogenous cells and conidia. i–j, l–n Conidia. k Conidiophores. o Germinated conidia. p Mycelium. q, r Culture on MEA (upper and lower view). Scale bars: d–i, k–p=20 μm, k=10 μm

Figure 2 – Phylogenetic tree generated from maximum likelihood (ML) analysis based on combined LSU, ITS and TEF1-α sequence data for the species from Melanommataceae. Periconia igniaria (CBS 379.86 and CBS 845.96) are used as the outgroup taxa. The dataset comprised 2694 characters after alignment including gaps (LSU=1245 bp; ITS=537 bp, TEF1-α=912 bp and RPB2=1006 bp). The RAxML analysis of the combined dataset yielded a best scoring tree with a final ML optimization likelihood value of − 14912.416315. The matrix had 871 distinct alignment patterns, with 36.52% undetermined characters or gaps. Estimated base frequencies were as follows: A=0.239281, C=0.249660, G=0.270492, T=0.240568; substitution rates AC=1.684833, AG=3.636355, AT=2.551537, CG=0.785971, CT=9.189334, GT=1.000000; gamma distribution shape parameter α=0.180969. Support values for maximum likelihood (MLBS) above than 75% and Bayesian posterior probabilities (BYPP) greater than 0.95 are given at the nodes. Ex-type strains are in bold and newly generated sequence is in blue