Trichobotrys effusa (Berk. & Br.) Petch

Zhang, Wen-Jing, Xu, Gui-Ping, Liu, Yu, Gao, Yang, Song, Hai-Yan, Hu, Hai-Jing, Zhou, Jian-Ping, Chen, Ming-Hui, Fan, Deng-Mei, Hu, Dian-Ming & Zhai, Zhi-Jun, 2024, Multi-gene phylogenetic analyses revealed two novel species and one new record of Trichobotrys (Pleosporales, Dictyosporiaceae) from China, MycoKeys 106, pp. 117-132 : 117-132

Trichobotrys effusa (Berk. & Br.) Petch , Ann. R. bot. Gdns Peradeniya 9: 169 (1924)

Fig. 4

Description.

Saprobic on the stems of decaying wood in freshwater habitat. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies effuse, grayish to nut brown, velvety. Mycelium mostly superficial, creeping and twining, composed of septate, branched, subhyaline to pale brown hyphae. Conidiophores 2–4 μm wide (x ̄ = 2.7 μm, n = 20), up to 650 μm long, mononematous, erect, straight or somewhat curving, columniform, moderately branched, verruculose, septate, thick-walled, echinulate, light brown to nut brown, gradually attenuated distally to an infertile, setiform apex. Conidiophore branches 7–26 × 2–4 μm (x ̄ = 14.0 × 3.2 μm, n = 16), fertile, 0–1 (– 2) - septate, verruculose, light brown to dark brown, individual cells typically have a slight swelling. Conidiogenous cells 3–10.5 × 2.5–6.5 μm (x ̄ = 6.6 × 4.0 μm, n = 10), monoblastic or polyblastic, integrated and terminal on lateral branches, apical or lateral; columniform or cannulate, erect or slightly curved, with several seriated conidiogenous locations, light brown to dark brown. Conidia 3.5–5 μm diam (x ̄ = 4.4 μm, n = 30), catenulate, simple or branched apical chains, aseptate, spherical, verruculose, echinulate, sometimes guttulate, transparent to dark brown or red brown.

Cultural characteristics.

Conidia germinating on PDA within 24 h. Colonies incubated on PDA media at 25 ° C attaining 11.5 mm diam after 11 days, in natural light, circular, white, cottony, with white dense aerial mycelium; reverse yellow, white at the margin part.

Material examined.

China. Guangxi Province: Guigang City, Pingtianshan National Forest Park , on decaying wood submerged in a freshwater stream, alt. 980.84 m, near 23.19 ° N, 109.51 ° E, 11 March 2023 and 16 May 2024, Wan Hu and Z. J. Zhai, HG 13 and HG 13-1 ( HFJAU 10296 , HFJAU 10372 ), ex-type living culture, JAUCC 6359 = JAUCC 6826 .

Notes.

According to phylogenetic analysis (Fig. 1 ), we can find that our new isolates cluster with Trichobotrys effusa FS 524 and T. effusa YMJ 1179 with high support (BS / PP = 100 / 1). Morphologically, our new collections are similar to the holotype of T. effusa except for the slightly larger conidia (3.5–5 μm vs. 3–4 μm), longer conidiophores (up to 650 μm vs. up to 200 μm), and slightly different colors in mycelium (grayish to nut-brown vs. dark purple-brown) ( Petch 1924). The difference in color might be due to the discrepancy in incubation time and the exposure to light or different observation angles under the microscope. The differences in the size of conidiophores and conidia are also occurring in another record of T. effusa , in which the conidiophores and conidia are described as being up to 1000 μm long and 5–7 μm in diameter, respectively ( Morgan-Jones et al. 1987). The differences among the holotype and our new collections suggest that factors such as habitat and incubation time may influence the size of conidia and conidiophores. Similar observations have also been discovered in the asexual morph of other fungal species ( Yang et al. 2018 b; Zhang et al. 2022; Shen et al. 2024). Owing to the unavailable molecular sequences in the holotype of T. effusa and the deficiency of morphological descriptions about T. effusa FS 524 and T. effusa YMJ 1179 , the possibility cannot be excluded that our new isolates are a different species to T. effusa . However, there are no significant morphological differences between our collections and the holotype. Therefore, we propose to identify the new collections as T. effusa until more strains have been examined. The new collection was collected from submerged, decaying wood in Guangxi Province, which is a new discovery in freshwater habitat in China.

Figures

Figure 1. Phylogenetic tree of Dictyosporiaceae inferred from the combined regions (ITS-LSU-SSU- tef 1 - α) using Maximum Likelihood (ML) analysis. The Periconia igniaria clade was used as the outgroup. PP ≥ 0.95 and BS ≥ 75 % were indicated around the branches. The new sequences generated in this study are given in red and type strains are in bold.

Figure 4. Trichobotrys effusa (HFJAU 10296, HFJAU 10372) a colonies on the substrate b conidiophores with conidia c portion of conidiophore with fertile lateral branches d – f conidiogenous cell with conidia g, h conidia i germinating conidia j, k culture on PDA from above (j) and reverse (k). Scale bars: 100 µm (a); 20 µm (b, c); 5 µm (d – i); 5 mm (j, k).