Pseudothielavia terricola X. W. Wang & Houbraken (2019)

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-

Pseudothielavia terricola X. W. Wang & Houbraken (2019)

Fig. 32

Description.

Sexual morph Cleistothecia 105–145 µm diam, non-ostiolate, globose, glabrous, black when mature, solitary to aggregated, mostly superficial, some submerged in PDA, aerial mycelium covered. Peridium brown, semi-translucent, membranous, textura epidermoidea. Asci subglobose to pyriform, hyaline when immature, eight-spored, 23.7–27.0 µm × 20.5–23.5 µm (x ̄ = 25.5 × 22.5 µm, L / W ratio = 1.13, n = 10). Ascospores 1 celled, olivaceous brown when mature, subglobose to ellipsoidal, some smooth, apical germ pore, 9.3–11.7 µm × 6.7–9.0 µm (x ̄ = 10.5 × 7.6 µm, L / W ratio = 1.39, n = 20). Asexual morph undetermined.

Culture characteristics.

Colony reaching 50 mm diam with thick white aerial mycelium, fluffy, edge irregularly, wavy margin, and similar to reverse side of the colony.

Material examined.

TAIWAN • Guanshan Township , Taitung County, 23°02'12.8"N, 121°11'22.0"E, serpentine soil in rice field, 2 nd November 2022, K. W Cheng, living culture NTUPPMCC 22-293 and NTUPPMCC 22-294 .

Notes.

Two strains ( NTUPPMCC 22-293 and NTUPPMCC 22-294 ) isolated in this study clustered within the clade containing ex-type strains, along with other representative strains of Pseudothielavia arxii and Pse. terricola , with strong statistical support (100 % / 1.00) (Fig. 33 ). Although both Pse. arxii and Pse. terricola exhibited no clear phylogenetic variation in our tree or in previous studies, they can be distinguished by differences in ascospore morphology ( Wang et al. 2019). The morphology of our strain ( NTUPPMCC 22-294 ) exhibited an apical germ pore, similar to that of Pse. terricola ( CBS 165.88 ) (Fig. 32 ). According to its original description ( Wang et al. 2019; Noguchi et al. 2022), Pse. arxii lacks an apical germ pore and instead possesses an oblique to lateral germ pore. Therefore, based solely on morphological similarity, we identified our strain as Pse. terricola . However, further studies are required to determine whether Pse. arxii and Pse. terricola represent two distinct species or a single species. This study represents the first discovery of a Pseudothielavia species in Taiwan.

Figures

Figure 32. Morphology of Pseudothielavia terricola NTUPPMCC 22-294. A, B 14 - days-old colony on PDA; C Ascomata; D Squashed ascomata; E Immature ascus; F Ascospores. Scale bars: 1 mm (C); 50 µm (D); 20 µm (E, F).

Figure 33. Maximum likelihood (ML) phylogenetic tree based on a concatenated dataset of ITS, LSU, rpb 2, and tub 2. In total, 26 strains representing 21 taxa were included in the concatenated dataset, with 2315 characters (ITS 531 bp, LSU 556 bp, rpb 2 809 bp, and tub 2 419 bp) including alignment gaps. The tree was rooted with Triangularia longicaudata CBS 252.57. 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.