Melnikomyces linderae M. L. Chen & X. Luo sp. nov.

Fig. 5

Etymology.

The epithet “ linderae ” refers to the host genus Lindera, from which the fungus was originally isolated.

Holotype.

HKAS 133201.

Description.

Sexual morph not observed. Asexual morph: Conidiophores 8.2–46.0 × 0.9–1.7 μm, macronematous, unbranched or branched, thick and smooth-walled, erect, straight or slightly flexuous, septate, subcylindrical, light brown to brown, usually paler towards apex, reduced to conidiogenous cells. Conidiogenous cells 3.5–15.9 × 0.7–1.5 μm, polyblastic, integrated, terminal or intercalary, pale brown to brown, sympodial, with one or more denticles in the apical region, denticles cylindrical, pale brown, 0.4–1.0 μm long. Conidia 3.0–6.4 × 1.8–2.7 μm, solitary, ellipsoidal to obovoid, occasionally slightly clavate, aseptate when young, 1 - septate when mature, sometimes 2 - septate, slightly constricted at the septum, hyaline to light brown, verrucose, rhexolytic secession. Chlamydospores 3.6–7.6 × 3.6–7.0 μm, lateral, intercalary or terminal, globose to subglobose, somewhat ellipsoid, hyaline to dark brown, thick and smooth-walled, in short or singly chains.

Culture characteristics.

Colonies on PDA reaching 2.1 cm diam. after 14 d at 28 ° C, flat, cottony to floccose, smooth margins, cream-colored to brown; reverse dark brown, margin cream-colored. On OA, cottony to floccose, dark brown to medium brown, with sparse to moderate aerial hypha; reverse brown.

Material examined.

China • Anhui Province, Huangshan City, Huangshan District, 30°1.74'N, 117°32.99'E, elevation 273 m, root of L. aggregata, 13 August 2023, Meng-Lan Chen, SRPZ 15-7 - 1 (Holotype: HKAS 133201, ex-type culture: KUNCC 24-17617, ex-isotype culture: KUNCC 25-20169).

Notes.

Melnikomyces linderae features pale brown to brown, narrow conidiophores (8.2–46.0 × 0.9–1.7 μm) together with polyblastic conidiogenous cells that bear cylindrical denticles. The verrucose, 1 (– 2) - septate conidia are 3.0–6.4 × 1.8–2.7 μm and are released by rhexolytic secession; globose to subglobose chlamydospores are present. Phylogenetically, M. linderae formed a sister clade to M. vietnamensis (Fig. 2). A comparison of nucleotide base pairs between them revealed differences of 24 / 527 bp (4.55 %, including 3 gaps) and 8 / 748 bp (1.06 %, no gaps) in the ITS and LSU sequences, respectively. Morphologically, M. linderae (KUNCC 24-17617) is distinguished from M. thailandicus (CBS 145767) and M. vietnamensis (CBS 136209) (Crous et al. 2014; Hernández-Restrepo et al. 2020). Melnikomyces thailandicus and M. vietnamensis have larger conidia than M. linderae. Those of M. thailandicus are smooth, fusoid, subhyaline, (8 –) 9.5–12 (– 13) × (2 –) 2.5 (– 3) μm, while those of M. vietnamensis are fusoid-ellipsoidal, (7 –) 9–10 (– 11) × (2.5 –) 3 (– 3.5) μm. Furthermore, M. thailandicus and M. vietnamensis have distinctly wider conidiophores (2.0–3.0 μm and 1.5–2.0 μm, respectively) than M. linderae (0.9–1.7 μm). Therefore, strains KUNCC 24-17617 and KUNCC 25-20169 are introduced herein as M. linderae sp. nov.