Parasarocladium formosum K. W. Cheng & H. A. Ariyaw., 2025

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-

Parasarocladium formosum K. W. Cheng & H. A. Ariyaw. sp. nov.

Fig. 24

Typification.

TAIWAN • Guanshan Township , Taitung County, 23°02'17.6"N, 121°11'26.3"E, serpentine soil in rice field, 3 rd November 2022, K. W. Cheng, holotype, NTUPPMH 22-221 (Permanently preserved in a metabolically inactive state), ex-holotype NTUPPMCC 22-288 .

Etymology.

Named after Formosa, the former name of Taiwan, where the type specimen was collected.

Description.

Sexual morph undetermined. Asexual morph Conidia were observed on WA. Conidiophores mostly solitary, phialidic, straight but some curved, smooth, hyaline, arising directly from aerial or substratal hyphe, unbranched, mono-phialides or adelophialides predominant, 7–18 × 2–3 μm. Conidia ellipsoidal, sometimes fusoid, hyaline, aseptate, smooth-walled, 1 - celled, several tiny guttules, arranged in slimy heads, 3.7–7.4 µm × 2.0–3.9 µm (x ̄ = 4.9 × 2.6 µm, L / W ratio = 1.94, n = 50).

Culture characteristics.

Colony exhibits slow growth, reaching 35 mm diam with creamy white, radially folded, slightly rugose at center region, smooth margin, reverse pale yellow.

Notes.

Parasarocladium formosum forms a distinct clade with strong support (94 % / 1.00), as a sister taxon to Pa. chondroidum in our multi-locus phylogenetic analysis (Fig. 25 ). Moreover, the ex-type strain of Pa. formosum ( NTUPPMCC 22-288 ) shows significant genetic divergence from its closest relative, the ex-type strain of Pa. chondroidum ( CBS 652.93 ), with 96.7 % identity in the ITS region (438 / 453 bp, including 4 gaps) and 93.1 % identity in the tef- 1 gene (752 / 808 bp). It is worth noting that Pa. chondroidum has been reported as an endophyte in Gramineae , whereas Pa. formosum NTUPPMCC 22-288 , although isolated from a paddy field, was recovered from soil and has not been identified as an endophyte ( Hou et al. 2023). Moreover, the conidia of our new species are slightly larger and straighter compared to the original description of Pa. chondroidum CBS 652.93 , which exhibited relatively smaller and curved conidia. (3.7–7.4 µm × 2.0–3.9 µm versus 3.4–8 µm × 1.2–2.5 µm) (Fig. 24 ; Hou et al. 2023). Based on these molecular and morphological differences, we propose our strain ( NTUPPMCC 22-288 ) as a novel species, Parasarocladium formosum .

Figures

Figure 24. Morphology of Parasarocladium formosum NTUPPMCC 22-288. A, B 14 - days-old colony on PDA; C – E Conidiophores, phialides, and conidiogenous cells; F Conidia. Scale bars: 20 µm (C); 10 µm (D – F).

Figure 25. Maximum likelihood (ML) phylogenetic tree based on a concatenated dataset of ITS, LSU, and tef- 1. In total, 19 strains representing 17 taxa were included in the concatenated dataset, with 2159 characters (ITS 505 bp, LSU 809 bp, and tef- 1 845 bp) including alignment gaps. The tree was rooted with Sarocladium ochraceum CBS 428.67. 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.