Parafuscosporella xishuangbannaensis R. Zhu & H. Zhang, 2023

Wang, Lin, Dong, Wei, Yang, Jun-Xian, Zhu, Rong, Zhang, Huang & Yu, Ze-Fen, 2023, Parafuscosporella xishuangbannaensis sp. nov. (Fuscosporellales, Sordariomycetes) from submerged wood in China, Phytotaxa 587 (3), pp. 218-228 : 221-226

Parafuscosporella xishuangbannaensis R. Zhu & H. Zhang , sp. nov. ( FIGURES 2 & 3 )

Index Fungorum number: IF900242; Facesoffungi number: FoF 14014

Etymology: in reference to Xishuangbanna, from where the holotype was collected.

Holotype: IFRD 9461

Saprobic on decaying wood submerged in freshwater. Sexual morph: undetermined. Asexual morph: Hyphomycetous. Colonies on natural substrata punctiform, granular, gregarious, black, glistening. Mycelium partly immersed, partly superficial, composed of septate, branched, smooth-walled, hyaline hyphae. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, monoblastic, integrated, terminal, hyaline, cylindrical, 2.8– 4.7 × 3.3–4.9 μm (x = 3.6 × 3.8 μm, n = 20). Conidia acrogenous, obovoid to subglobose, brown to dark brown, with a septum near the base, smooth-walled, 18–29 × 14–27 μm (x = 23.8 × 21.5 μm, n = 30); basal cell wedge-shaped, paler than the other cells, 1.5–5 × 3.5–7.5 μm (x = 2.8 × 5 μm, n = 20).

Cultural characteristics: Conidia germinating on PDA within 24 hours. Germ tubes are produced from the basal cell. Colonies on PDA are very slow-growing, reaching 10 mm diameter after 12 weeks at 20–25˚C, pale yellow to yellow from above and below, with sparse mycelium, entire at the edge. Conidiophores reduced to conidiogenous cells. Conidiogenous cells cylindrical, hyaline to pale brown, 10–32 × 2–5.5 μm (x = 21.5 × 3.5 μm, n = 20). Conidia globose to subglobose, aseptate or with a septum near the base, smooth, hyaline when young, pale brown to brown at maturity, 20–28 × 17–27 μm (x = 23.4 × 21.5 μm, n = 30), sometimes with a wedge-shaped, paler cell at the base, 2.5–8(–21) × 2.5–4.5 μm (x = 5 × 4 μm, n = 30).

Material examined: CHINA. Yunnan Province, Xishuangbanna, Manfeilong reservoir, on submerged decaying wood of an unidentified plant, 7 November 2020, R. Zhu, N 94 ( IFRD 9461 , holotype), ex-living culture IFRDCC 3133 .

Notes: The multi-locus phylogenetic analyses of combined LSU, SSU, ITS and rpb2 sequence data show that our strain forms a separate branch in Parafuscosporella and clusters with two strains of P. pyriformis ( FIGURE. 1 ). Morphologically, our isolate is similar to P. pyriformis in having obovoid to subglobose conidia and overlapping conidial size. However, the two taxa can be easily distinguished by the characteristics of the conidiophores. Parafuscosporella pyriformis has numerous, cylindrical or moniliform conidiophores ( Yang et al. 2020), while the conidiophores of our new isolate are reduced to conidiogenous cells. Additionally, the conidia of the new isolate forming in culture are bigger than those of P. pyriformis (20–28 × 17–27 μm vs. 8–12 × 7–12 μm). Comparisons of nucleotides show that there are three (0.3%, including 2 gaps) and 20 (3.4%, including 4 gaps) nucleotide differences in LSU and ITS regions respectively, which supports them to be different species as per the guidelines of Jeewon and Hyde (2016). Based on the morphological and molecular differences, we introduce our isolate as a new species in Parafuscosporella , namely P. xishuangbannaensis . Morphologically, P. moniliformis and P. mucosa are similar to P. xishuangbannaensis in their globose to subglobose conidia in culture. However, the shape of conidiogenous cells and conidia on the natural substrates are different. The conidiogenous cells of P. xishuangbannaensis are only cylindrical as per the description above, while those of P. mucosa are globose, subglobose, ellipsoidal or clavate. The conidia of P. xishuangbannaensis are obovoid to subglobose, while those of P. moniliformis are ellipsoidal to broadly obpyriform and those of P. mucosa are obovoid to obpyriform ( Yang et al. 2016).

Figures

FIGURE 1. Maximum likelihood majority rule consensus tree based on a dataset of combined LSU, SSU, ITS and rpb2 sequence data. Bootstrap support values for maximum likelihood (ML BS) equal to or greater than 75% and Bayesian posterior probabilities (BI PP) equal to or greater than 0.95 are given near the nodes. The strain numbers are noted after the species names. The ex-type strains are in bold and the new isolate is in red bold. The tree is rooted with Canalisporium grenadoideum (SS03615) and Savoryella aquatica (SS 03801).

FIGURE 2. Parafuscosporella xishuangbannaensis (IFRD 9461, holotype) a, b Colonies on natural substrate. c Squash mount of conidia. d, g Conidiogenous cells with conidia. e–j Conidia. Scale bars: c = 20 μm, d = 10 μm, e–j = 5 μm.

FIGURE 3. Sporulation of Parafuscosporella xishuangbannaensis on PDA. a, b Culture on PDA, a from above, b from reverse. c–l Conidiophores, conidiogenous cells and conidia from culture. Scale bars: c–g, i–l = 20 μm, h = 10 μm.