Guttulate freshwater fungus (Paramirandina guttulata) joins Paramirandina aquatica and Paramirandina cymbiformis

NEWS - Guttulate freshwater fungus (Paramirandina guttulata H.W. Shen, K.D. Hyde & Z.L. Luo, sp. nov.) is a morphologically striking hyphomycete species collected from a freshwater habitat in Dujuanhu Lake in Yunnan Province, China, at an elevation of 2500 m as new to science based on unique morphological features and combined phylogenetic analysis of LSU and ITS sequences.

Paramirandina was introduced by Liu et al. (2023) to accommodate two lignicolous freshwater fungi from lotic habitats in Guizhou Province, with Paramirandina aquatica as the type species. This genus is morphologically similar to Heliocephala and Mirandina, but can be distinguished by the morphology of conidia and conidiogenous cells.

During the investigation of lignicolous freshwater fungi from a highland lake in Yunnan Province, the researchers discovered the striking hyphomycete on submerged woody substrates. Detailed morphological descriptions and comprehensive phylogenetic analyses confirmed the distinctiveness and phylogenetic placement of the species within Paramirandina.

The new species is similar to P. aquatica and Paramirandina cymbiformis. However, P. guttulata can be distinguished from P. aquatica by its longer and clustered conidiophores (264–310 × 4.5–5 µm vs. 138–200 × 4.5–8 µm) and slightly larger conidia (33–38 × 6–7.5 µm vs. 23–34 × 4–7.5 µm). It differs from P. cymbiformis by having clustered conidiophores and larger conidia (33–38 × 6–7.5 µm vs. 24–30 × 5–6.5 µm).

Comparison of ITS nucleotide bases and LSU sequence data between P. guttulata and P. aquatica showed differences of 7.5% (51/531 bp, including 11 gaps) and 1.6% (13/813 bp, without gaps), respectively. LSU sequences between P. guttulata and P. cymbiformis showed differences of 1.6% (12/768 bp, without gaps).

DESCRIPTION

Saprobic on submerged decaying wood in a freshwater lake. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies on natural substrates effuse, hairy, mostly in small groups, sometimes scattered, dark brown, with whitish conidial masses at the apex. Mycelium mostly immersed, composed of branched, septate, hyaline to brown, smooth-walled hyphae. Conidiophores (230–)264–310(–330) × 4.5–5(–6) µm (x̄ = 287 × 5 µm, n = 35), macronematous, mononematous, erect, gregarious, unbranched, cylindrical, straight to flexuous, septate, gradually tapering from the base to the apex, with the base transitioning from dark brown to hyaline towards the apex. Conidiogenous cells (31–)40–60(–70) × 4–5 µm (x̄ = 50 × 5 µm, n = 20), polyblastic, integrated, terminal, indeterminate, sympodial, cylindrical, pale brown to hyaline, smooth. Conidia (31–)33–38(–44) × 6–7.5 µm (x̄ = 35 × 7 µm, n = 40), acropleurogenous, solitary or in chains, fusiform, cymbiform, fusoid-clavate, straight or slightly curved, truncate at the base, obtuse at the apex, hyaline, 4–6-septate, smooth, guttulate, sometimes bearing a new conidium at the apex.

Culture characteristics: Conidia germinating on PDA medium and germ tubes produced from both ends of conidium within 12 h. Colonies on PDA medium reaching 1–1.5 cm diam. after one month at room temperature (around 25°C) in dark, circular, with dense, velvety, pale brown to brown mycelium from above, brown from below.

Original research

Shen H-W, Bao D-F, Wu N, Al-Otibi F, Luo Z-L, Hyde KD (2024). Paramirandina guttulata (Microthyriaceae, Microthyriales), a new lignicolous freshwater fungi from a plateau lake in Yunnan Province, China. Biodiversity Data Journal 12: e137989, DOI:10.3897/BDJ.12.e137989

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