Rhodoveronaea aquisubtropica H. Zhang & J. Ma sp. nov.

Fig. 2

Etymology.

“aqui-’’ refers to aquatic habitat of this fungus, and ‘‘-subtropica’’ means the climate type where the fungus was collected.

Holotype.

GZAAS 25-0665.

Description.

Saprobic on decaying wood in a freshwater habitat. Sexual morph Undetermined. Asexual morph Hyphomycetous. Colonies on wood effuse, hairy, scattered or aggregated, brown. Mycelium partly superficial, partly immersed, composed of branched, septate, guttulate, smooth-walled, hyalina to brown hyphae. Conidiophores 204–270 × 4.9–7 μm (x ̄ = 241.5 × 6 μm, n = 20), macronematous, mononematous, erect, flexuous, solitary, cylindrical, smooth-walled, septate, unbranched, black brown, mid brown, paler towards the apex. Conidiogenous cells polyblastic, integrated, terminal, determinate, sympodial, forming a rachis with subdenticulate loci, flexuous, pale brown to subhyalina, pigmented, with inconspicuous denticles. Conidia 10.5–13.5 × 4–5.5 μm (x ̄ = 12.5 × 4.7 μm, n = 25), acropleurogenous, aggregated in slimy masses, ellipsoidal to narrowly obovoid, 1–3 - septate, mostly 3 - septate, smooth-walled, pale yellowish brown, guttulate, thin-walled, sometimes slightly constricted at the septa.

Culture characteristics.

Conidia germinating on PDA within 12 hours, producing germ tubes from the conidial body. Colonies on PDA are circular with a raised surface and entire margin, reaching 30 mm in diameter after 36 days at room temperature (approximately 25 ° C), and are brown to reddish brown in color on both the surface and reverse sides.

Material examined.

China • Guizhou Province, Chishui City, Chishui River, on decaying submerged wood in a freshwater habitat, 10 October 2024, Hong Zhang & Jian Ma, CS 12 (GZAAS 25-0665, holotype), ex-type living cultures GZCC 25-0635; Ibid., CS 18 (GZAAS 24-0083, paratype), living culture GZCC 24-0170.

Notes.

In our phylogenetic tree (Fig. 1), our isolates (GZCC 25-0635 and GZCC 24-0170) formed a sister clade to Rhodoveronaea aquatica (GZCC 20-0447 and MFLUCC 18-1339) with 76 % ML support. A comparison of LSU, ITS, SSU, and tef 1 - α sequences between Rhodoveronaea aquatica (MFLUCC 18-1339) and R. aquisubtropica (GZCC 25-0635) and reveals their nucleotide differences of 3 / 774 bp (0.4 %, without gap), 20 / 502 bp (4 %, including 4 gaps), 5 / 852 bp (0.6 %, including 3 gaps), and 29 / 882 bp (3.3 %, without gap), respectively, indicating that they are distinct species. Morphologically, Rhodoveronaea aquisubtropica (GZAAS 25-0665) differs from R. aquatica (MFLU 18-1593, ex-type) by its narrower conidiophores (204–270 × 4.9–7 μm vs. 182–310 × 9–13 μm), and smaller conidia (10.5–13.5 × 4–5.5 μm vs. 23–27 × 9–11 μm) (Luo et al. 2019). Therefore, we introduce Rhodoveronaea aquisubtropica as a novel species based on the multi-gene phylogenetic analysis and morphological differences.