Clonostachys rogersoniana Schroers, Studies in Mycology 46: 109 (2001)

Index Fungorum number: IF 485131; Mycobank number: MB 485131; Facesoffungi number: FoF 07755; Fig. 1

Fungicolous on a bolete mushroom. Sexual morph: Not observed. Asexual morph: on the host, Mycelium white cottony mass. On PDA, hyphomycetous, Hyphae 1–3.5 μm (x̅=2.5 μm, n=30) wide, branched, septate, hyaline, hyphal coils observed. Conidiophores scattered on the agar media or arising from the aerial hyphae, mostly dominant towards the margin, hyaline, penicillate, septate, stipes 60–170×2–6 μm (x̅= 117 × 4 μm, n = 20). Penicilli 55–78 × 50–96 μm (x̅=66.5×73 μm, n=20), solitary to gregarious, bi- to quarter verticillate, non sporodochial; branches of the penicillus divergent, each branch terminating in metulae and adpressed phialides. Phialides 10–26×1.7–3.6 μm (x̅=16.5×2.6 μm, n=30), in whorls of 2–4, narrowly flask-shaped, slightly tapering toward the apex. Intercalary phialides not observed. Conidial masses white to light yellow. Conidia 5–9×1.5–4 μm (x̅=6.5×2.5 μm, n=40, broadly ellipsoidal to oval, rarely minutely curved, ends broadly rounded, hilum laterally displaced, almost median or invisible, hyaline, smooth-walled.

Culture characteristics – Colonies on PDA attaining 60–70 mm diameter after 14 days at 25 °C, velvety to lanose, dense, aerial mycelium with hyphae arranged in strands, colony front initially white and develops brown spots when getting older, colony reverse white to medium brown with irregular margins.

Material examined – Thailand, Chiang Mai province: Mae Tang, Pa Pae, Ban Pha Deng, isolated from the white mycelium growing on a bolete mushroom, 07 July 2021, AJ. Gajanayake, MR 01 (inactive dry culture, MFLU 23-0484, new host record), living culture, MFLUCC 23-0203.

GenBank numbers – ITS=OR473265, tub2=OR804262.

Notes – Our isolate (MFLUCC 23-0203), clusters within Clonostachys rogersoniana with bootstrap support of 100% ML, 1.00 BYPP (Fig 2). Furthermore, the morphology of our isolate (MFLUCC 23-0203) resembles the original description and illustrations of C. rogersoniana by Schroers (2001). However, when our strain is compared with the strain described by Schroers (2001), there are slight dimensional differences (conidiophores: 60–170×2–6 μmvs 60–200 μm×3–5 μm, height of the penicilli: 55–78 μm vs. 50–100 μm, length of the phialides: 10–26 μm vs. 11.8–26.8 μm, conidia: 5–9 ×1.5–4 μm vs. 5.8–7.2×3–3.8 μm) in morphological structures. The reason may be the differences in the media in which the colonies were grown.

Clonostachys rogersoniana has been commonly isolated from soil whereas it has also been isolated from bark of dead twigs, leaf litter and decaying seed pods (Schroers 2001; Perera et al. 2020). This species has shown a cosmopolitan distribution while it has been mostly reported from warmer or tropical regions (Schroers 2001). Therefore, most probably C. rogersoniana spores from the soil on the bolete mushroom would eventually lead to growth as a fungicolous fungus. Previously, Clonostachys byssicola, C. subquaternata and C. rosea have been reported as fungicolous species (Sun et al. 2019). However, C. rogersoniana has been extensively studied for its potential to produce secondary metabolites whereby, a cordyceps-colonizing strain of C. rogersoniana was among them (Wang et al. 2017a, b; Wang et al. 2019; Han et al. 2020; Tapfuma et al. 2023). To the best of our knowledge, this is the first report of Clonostachys rogersoniana as a fungicolous fungus on a bolete mushroom, from Thailand.

Figure 1 – Clonostachys rogersoniana (MFLU 23–0203) a Host. b, c 14 days old colony on PDA (b. above, c. below). d Sporulation on PDA. e–g Conidiophores with phialides and conidial attachments. h Hyphal coils. Hyphal coils. i Conidia. Scale bars: a=2.5 cm, b, c=40 mm, d=200 μm, e, f=45 μm, g=30 μm, h=25 μm, i=5 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS and tub2 sequence data representing the Clonostachys species. Related reference sequences were downloaded from GenBank based on previously published data from Perera et al. (2020) and Zeng and Zhuang (2022). Seventy-six taxa are included in the combined analyses. Fusarium acutatum (CBS 402.97) and
Nectria cinnabarina (CBS 18987) are used as the outgroup taxa. The best scoring RAxML tree with a final likelihood value of − 13,172.451 is presented. The matrix had 639 distinct alignment patterns, with 19.91% of undetermined characters or gaps. The proportion of invariable sites was 0.316. Estimated base frequencies were as follows: A=0.250, C=0.250, G=0.250, T=0.250; substitution rates: AC=1.00000, AG=2.80366, AT=1.00000, CG=1.00000, CT=4.24917, GT=1.00000; gamma distribution shape parameter α=0.692. The value of the average standard deviation of the split frequencies of BYPP analysis was 0.008389. Bootstrap support values for ML equal to or greater than 70% and BYPP equal to or greater than 0.90 are given near the nodes. The newly generated sequence is in blue. The type strains are indicated in black bold