Westerdykella dispersa K. Cejp & A. A. Milko (1964)

Cheng, Kai-Wen, Yang, Jiue-in, Srimongkol, Piroonporn, Stadler, Marc, Karnchanatat, Aphichart & Ariyawansa, Hiran A., 2025, Fungal frontiers in toxic terrain: Revealing culturable fungal communities in Serpentine paddy fields of Taiwan, IMA Fungus 16, pp. e 155308-e 155308 : e155308-

Westerdykella dispersa K. Cejp & A. A. Milko (1964)

Fig. 15

Description.

Sexual morph Cleistothecia 187–296 µm diam, globose to subglobose, glabrous, dark brown to black when mature, superficial or submerged in PDA. Peridium single-layered, light brown, translucent, membranous, angular cells. Asci subglobose to ovoid, hyaline when immature, brown when mature, 32 - spored, 11.0–13.6 µm × 9.7–11.8 µm (x ̄ = 12.3 × 10.8 µm, L / W ratio = 1.14, n = 30). Ascospores ellipsoidal, smooth, subhyaline to light brown, 2 guttules, no germ-slits, 1.8–2.7 µm × 3.7–4.5 µm (x ̄ = 2.3 × 4.0 µm, L / W ratio = 1.82, n = 50). Asexual morph Conidiomata abundant on PDA at 25 ° C, 7 days post-inoculation, 44–88 µm, globose, subglobose to irregular due to fusion of two or more, glabrous, brown, ostiolate, superficial. Conidia borne terminally in camel brown gelatinous mass, ellipsoidal, subglobose, some pyriform, smooth, hyaline, 0 to 2 guttules, 1.8–2.7 µm × 3.1–4.0 µm (x ̄ = 2.1 × 3.3 µm, L / W ratio = 1.62, n = 50).

Culture characteristics.

Colony exhibit rapid growth, reaching 80 mm daim with slightly diffuse and beige margins, yellow to pale orange pigmentation radiating outward in a concentric ring pattern, texture velvety to slightly cottony. The cleistothecia and abundant conidiomata caused the center to appear black or dark yellow.

Material examined.

TAIWAN • Guanshan Township , Taitung County, 23°02'12.8"N, 121°11'22.6"E, serpentine soil in rice field, 3 rd November 2022, K. W. Cheng, living culture NTUPPMCC 22-260 to 270 .

Notes.

Westerdykella dispersa have a global distribution and have been isolated from diverse substrates, including soil from the Netherlands and Nigeria ( Arenal et al. 2007), freshwater ecosystem sediments in Brazil and Korea ( da Silva et al. 2003; Goh et al. 2021), marine sediments in China and Spain ( Xu et al. 2017; Guerra-Mateo et al. 2024), as endophytes of Phragmites australis in Italy ( Angelini et al. 2012), and in rare cases, isolated from a neutropenic patient ( Clum 1955; Sue et al. 2014). In the multi-locus phylogenetic analysis conducted in this study, strains identified as W. dispersa were separated into three distinct clusters designated as Clades A, B, and C (Fig. 13 ). Strains NTUPPMCC 22-260 , 22-261, 22-263 and 22-266 grouped with the ex-type strain of W. dispersa ( CBS 297.56 ) in Clade B. Two other representative strains, CBS 390.61 and CBS 288.67 , along with our strains NTUPPMCC 22-262 , 22-264, 22-265, and 22-267 to 22-270, formed a separate clade (Clade C), which is sister to the main W. dispersa lineage. Additionally, strain CBS 508.75 formed a basal clade (also referred to as Clade A) relative to Clades B and C, complicating the delineation of precise species boundaries. When comparing sequence identity, the representative strain NTUPPMCC 22-269 , which clusters in Clade C, showed 97.6 % similarity (925 / 948 bp) in the tub 2 gene to the ex-type strain of W. dispersa ( CBS 297.56 ). This strain also formed a strongly supported clade (80 % bootstrap support) sister to the clade containing the ex-type strain in single gene phylogeny of tub 2 (See Suppl. material 2: fig. S 1). However, no significant genetic divergence was observed between these strains in the ITS and LSU regions (ITS: 433 / 437 bp, identities 99.1 %, including 3 gaps; LSU: 824 / 830 bp, identities 99.4 %, including 4 gaps). As shown in Fig. 15 , although PDA cultures exhibited slight variation in colony coloration ( NTUPPMCC 22-266 representing Clade B and NTUPPMCC 22-269 representing Clade C; yellow to pale orange versus grayish-white to pale gray-green), other micromorphological features did not show notable differences (See Suppl. material 1: table S 4). Additionally, relying solely on culture characteristics is not a reliable method for delineating fungal species ( Jeewon and Hyde 2016). Therefore, based on molecular similarity, phylogenetic placement, and morphological consistency, we tentatively identify strains in three clades as W. dispersa . The observed genetic variation may be related to their geographical origin or the specific habitats from which these strains were isolated. Consistent with previous studies ( Sue et al. 2014), both sexual and asexual stages were observed in culture for W. dispersa in the present study. This report represents the first record of W. dispersa in Taiwan.

Figures

Figure 13. Maximum likelihood (ML) phylogenetic tree based on a concatenated dataset of ITS, LSU, and tub 2. In total, 56 strains representing 17 taxa were included in the concatenated dataset, with 2314 characters (ITS 459 bp, LSU 865 bp, and tub 2 990 bp) including alignment gaps. The tree was rooted with Preussia funiculata Huhndorf 2577 and P. typharum CBS 107.69. MLB ≥ 70 % and BPPs ≥ 0.95 were shown at each node; values lower than these thresholds are indicated by a hyphen (–). The scale bar indicates the number of estimated substitutions per site. The strains introduced in this study are in red and novel species are in bold. The ex-type strains are marked with T.

Figure 15. Morphology of Westerdykella dispersa NTUPPMCC 22-266. A, B 14 - days-old colony on PDA; C Ascomata (red arrow) and conidiomata (blue arrow); D Squashed ascomata; E Conidiomata and ostiolate; F Peridium; G Asci; H Ascospores; I Conidia. Morphology of Westerdykella dispersa NTUPPMCC 22-269. J, K 14 - days-old colony on PDA; L Ascomata (red arrow) and conidiomata (blue arrow); M Ascospores; N Conidia. Scale bars: 0.5 mm (C, L); 0.1 mm (D); 20 µm (E – G, M); 10 µm (H, I, N, O).