Sarocladium formosanum 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-

Sarocladium formosanum K. W. Cheng & H. A. Ariyaw. sp. nov.

Fig. 26

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 22-222 (Permanently preserved in a metabolically inactive state), ex-holotype NTUPPMCC 22-289 .

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 solitary, hyaline, straight to slightly flexuous, smooth-walled, arising from hyphal ropes or vegetative hyphae. Phialides subulate, hyaline, wide at the base, with, 13–30 µm long. Adelophialides and schizophialides not observed. Conidia unicellular, cylindrical with rounded ends, hyaline, smooth-walled, 1 - celled, few with inconspicuous 1 to 2 guttules on the end (s), sometimes aggregated in clusters forming a slimy head, 3.5–5.3 µm × 1.1–2.1 µm (x ̄ = 4.4 × 1.5 µm, L / W ratio = 3.08, n = 50).

Culture characteristics.

Colony exhibit slow growth, reaching 35 mm diam with flat, pale orange, wrinkled in the center, slimy, and smooth margin. The reverse side of the colony displayed similar characteristics.

Notes.

In the present study, Sarocladium formosanum forms a distinct clade with strong support (99 % / 1.00) based on multi-locus phylogenetic analysis (Fig. 27 ). Moreover, S. formosanum shows significant genetic divergence from its closest relatives, ex-type strain of S. strictum ( CBS 346.70 ) and S. bactrocephalum ( CBS 749.69 ) with 95.5 % identity to S. strictum (677 / 710 bp) and 93.1 % identity to S. bactrocephalum (661 / 710 bp) in the rpb 2 gene. Morphologically, S. formosanum lacks adelophialides, schizophialides, and chlamydospores, which distinguishes it from S. mali (Fig. 26 ; Hou et al. 2019). Several Sarocladium species have been recorded in Taiwan. S. spinificis was reported as an endophyte of the coastal grass Spinifex littoreus ( Yeh and Kirschner 2014) , while S. attenuatum , S. oryzae , S. sparsum , and S. spirale were isolated from rice grains and leaf sheaths ( Ou et al. 2020). However, our species, S. formosanum and S. serpentinicola , were isolated from serpentine environments and formed distinct clades from these previously reported species in the phylogeny. While this study establishes S. formosanum as a distinct species, future studies should aim to recover additional isolates from similar environments to further validate its phenotypic variation and ecological distribution.

Figures

Figure 26. Morphology of Sarocladium formosanum NTUPPMCC 22-289. A, B 14 - days-old colony on PDA; C – E Conidiophores and phialides; F Conidia. Scale bars: 10 µm (C – F).

Figure 27. Maximum likelihood (ML) phylogenetic tree based on a concatenated dataset of ITS, LSU, rpb 2, and tef- 1. In total, 45 strains representing 38 taxa were included in the concatenated dataset, with 2821 characters (ITS 497 bp, LSU 779 bp, rpb 2 734 bp, and tef- 1 811 bp) including alignment gaps. The tree was rooted with Parasarocladium breve CBS 150.62. 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.