Parafuscosporella nilotica Abdel-Aziz sp. nov.

Index Fungorum number: IF 557838; MycoBank number: MB 557838; Facesoffungi number: FoF 09199; Fig. 1

Etymology – Named after the River Nile, where this fungus was collected.

Holotype – CBS H-22128

Saprobic on the surface of decaying submerged wood in a freshwater river. Sexual morph Undetermined. Asexual morph Colonies on natural substrate, effuse, black. Mycelium partly immersed, partly superficial, composed of septate, hyaline hyphae, 1.5–3 μm wide. Conidiomata 300–600 μm diam. (x̅=421 μm, n=10), sporodochial, scattered, sphaerical to cushion-shaped, with jelly-like cover, gelatinous. Conidiophores micronematous, mononematous, either reduced to conidiogenous cells and conidia born directly on hyphae or when present unicellular, cylindrical to clavate, smooth-walled, hyaline, 3–7 μm long, 1.5–3 μm wide. Conidiogenous cells holoblastic, monoblastic, integrate. Conidial secession rhexolytic. Conidia 18–22×11–15 μm (x̅=21×13.5 μm, n=50), acrogenous, obpyriform, with a septum near the base, smooth, brown to dark brown, basal cell paler.

Culture characteristics – Conidia germinating on PDA within 24 h at 25 °C and germ tubes produced from both ends. Colonies on PDA reaching 1–1.5 cm diam. after 1 month at 25 °C, dark-brown, same from below.

Material examined – EGYPT, Sohag City, the River Nile, on decaying submerged wood, 14 August 2012, F.A. Abdel-Aziz (CBS H-22128, holotype), ex-type living culture (MF 1312).

GenBank numbers – ITS=MN921198, SSU=MN921199.

Notes – Phylogenetic analyses of ITS placed Parafuscosporella nilotica as distinct novel species within the Parafuscosporella clade with 87% MLBS, 95% MPBS, 0.98 BYPP support (Fig. 2). Parafuscosporella nilotica differs from the other Parafuscosporella species in having simple, micronematous, cylindrical to clavate conidiophores, whereas other species have macronematous, mostly moniliform, with globose to subglobose, ellipsoidal or clavate cells (Fig. 1). Parafuscosporella nilotica has much smaller conidial sizes than all species; 18–22×11–15 μm vs 20–29 × 13–19 μm for P. aquatica; (37.5–)40–47.5 × (25–)27.5–42.5 µm for P. garethii; 28–37×14–21 μm for P. moniliformis; 26.5–36 × 12–26 μm for P. mucosa and 23–30×16–26 μm for P. pyriformis (Boonyuen et al. 2016; Yang et al. 2016, 2020).

Figure 1 – Parafuscosporella nilotica (CBS H-22128, holotype). a, b Vertical section through sporodochium. c, d Squash of sporodochium. e–l Conidia at different stages of development. Scale bars: a, c=120 µm, b, d=20 µm, e, i=10 µm, f–h, j–l=5 µm

Figure 2 – Phylogenetic relationship of Parafuscosporella nilotica with related taxa in Fuscosporellaceae based on the nucleotide sequences of the ITS. The maximum likelihood (ML) tree (-ln likelihood=4928.50) was constructed in MEGA X (Kumar et al. 2018). The maximum parsimonious data set of the combined genes consisted of 25 taxa with 3 representatives of Savoryellales are used as the outgroup taxa. The dataset includes 503 total characters, of which 175 were constant, 30 parsimony-uninformative and 298 parsimony-informative. The parsimony analyses of the data matrix yielded 3 equally most parsimonious trees with a tree length of 1021 steps [consistency index (CI)=0.6298, homoplasy index (HI)=0.3702, retention index (RI)=0.7816, rescaled consistency index (RC)=0.4923]. Phylogenetic trees obtained from ML, maximum parsimony (MP) and Bayesian inference posterior probabilities (BIPP) were similar in topology. Bootstrap support on the nodes represents MLBS and MPBS equal to or greater than 50%. Branches with a BYPP of equal to or greater than 95% are in bold. The new taxon is in yellow box