Natipusilla aquatica Y.X. Shu, W. Dong & K.D. Hyde, in Dong et al., Fungal Diversity [15] (2025)

Index Fungorum number: IF 902615; MycoBank number: MB 902615; Facesoffungi number: FoF 17149; Fig. 1

Etymology – in reference to the aquatic habitats where the fungus was collected.

Holotype – MHZU 24-0585

Saprobic on submerged Taxodium distichum in fresh water habitats. Sexual morph: Ascomata 90–130 µm high, 90–125 µm diam. (x̄ = 107 × 123 µm, n = 5), scattered or gregarious, superficial, globose, pale brown, membranous, subhyaline when young, becoming brown with age, nonostiolate, apapillate. Peridium 15–20 µm thick, consisting of 4–6 layers of large, thick-walled cells of textura globulosa, dark brown to black in outer 1–3 layers, hyaline in inner 3–4 layers. Pseudoparaphyses 1.5–2.5 µm wide, septate, constricted at the septa, branched, few, persistent. Asci 60–110 × 20–30 µm (x̄ = 83 × 26 µm, n = 10), 8-spored, bitunicate, broadly clavate, short pedicellate when young, becoming sessile with age. Ascospores 28–35 × 9–11 µm (x̄ = 33 × 9.5 µm, n = 30), fusiform, slightly curved, 1-septate and hyaline when young, constricted at the septum, upper cell slightly broader than the lower cell, becoming 2–3-septate and brown with age, guttulate, surrounded by a thin, mucilaginous sheath, 2–3 µm wide. Asexual morph: undetermined.

Culture characteristics – ascospores germinating on PDA within 24 h. Colonies on PDA reaching 10–15 mm diam. after 15 days at room temperature, circular, with dense, velvety; from above, pale brown and dense in the middle; from below, dark brown, with smooth and light brown edge.

Material examined – China, Guangdong Province, Guangzhou City, N 23° 18′, E 113° 45′, on dead root of Taxodium distichum submerged in a small river, 21 September 2022, Y.X. Shu, FW2a (MHZU 24-0585, holotype); ex-type culture, ZHKUCC 24-1065; ibid., (MHZU 24-0586, isotype); ex-isotype culture, ZHKUCC 24-1066.

GenBank accession numbers – ZHKUCC 24-1065 = LSU: PQ276765, SSU: PQ276763; ZHKUCC 24-1066 = LSU: PQ276766, SSU: PQ276764.

Notes – Natipusilla aquatica clusters as a sister taxon to N. naponensis in our multi-locus phylogenetic analysis (Fig. 2). The two species exhibit similar morphology in the shape of asci and ascospores. However, N. aquatica can be distinguished from N. naponensis in having longer and thinner asci (60–110 µm × 20–30 µm vs. 65–69 µm × 24–36 µm), slightly shorter ascospores (28–35 µm long vs. 33–37 µm long), and the presence of a mucilaginous sheath (Ferrer et al. 2011). In terms of DNA sequence data comparison, there is a difference of 4.29% (36 out of 839) and 1.82% (19 out of 1040) in nucleotide variations within the LSU and SSU genes, respectively, between N. aquatica ZHKUCC 24-1065 and N. naponensis ILL AF217-1A. Therefore, N. aquatica is established as a novel species within Natipusilla.

Figure 1 – Natipusilla aquatica (MHZU 24-0585, holotype). a Ascomata on woody substrate. b Ascoma. c, d Section of an ascoma. e Pseudo-paraphyses. f, g Asci. h–j Ascospores. k Ascospore in Indian Ink. l, m Colony on PDA (front and below). Scale bars:  c = 50 µm, e = 5 µm, d, f, g = 20 µm, h–k = 10 µm.

Figure 2 – Maximum likelihood consensus tree inferred from the combined LSU and SSU multiple sequence alignments. Bootstrap support values for maximum likelihood (ML, first value) equal to or greater than 80% and Bayesian posterior probabilities from MCMC analyses (BYPP, second value) equal to or greater than 0.95 are given above the nodes. The scale bar indicates expected changes per site. The tree is rooted to Dendrographa decolorans Ertz13556 and D. decolorans Ertz13826. Ex-type strains are indicated with “T”. The newly generated sequences are indicated in red.