Meliola fusconigra Khan M. B. & T. C. Wen, 2025

Meliola fusconigra Khan M. B. & T. C. Wen sp. nov.

Fig. 3 View Figure 3

Etymology.

From Latin, “ fusco ” meaning dark and “ nigra ” meaning “ black, ” referring to the distinct dark black colonies of species on natural substrate.

Diagnosis.

Appressoria clavate, brown, unilateral, and antrorse; ascomata globose to subglobose with a central ostiole. Phialides flask-shaped, well-developed, and mixed with appressoria; ascospores cylindrical to oblong, large, smooth-walled, and dark brown at maturity.

Holotype.

China • Yunnan Province, Laifengshan National Forest Park, Muhammad Binyamin Khan , 26 July 2024, HKAS 146645 View Materials , GenBank accession numbers PV 298261 (SSU) and PV 298245 (LSU).

Additional materials examined.

China • Yunnan Province, Gaoligongshan, Muhammad Binyamin Khan , 27 July 2024, HKAS 146646 View Materials , HKAS 146647 View Materials , and HKAS 146648 View Materials , GenBank accession numbers PV 299282 , PV 298262 , and PV 298263 (SSU); PV 446596 , PV 297977 , and PV 454349 (LSU)

Habitat.

On leaving leaves of Xylopia aethiopica .

Description.

Biotrophic on the surface of living leaves of X. aethiopica . Colonies 4–8 mm in diameter, epiphyllous, dense to subdense, dark black. Hyphae superficial, black, straight to substraight, branched, black dark at septa, each cell 18–88 μm long (x ̄ = 53 μm, n = 10), loosely reticulate, with dark black setae. Hyphal setae 291–306 × 2–6 μm (x ̄ = 298 × 4 μm, n = 10), narrowly cylindrical, rounded to acute at the apex. Appressoria 24–28 × 11–15 μm (x ̄ = 26 × 13 µm, n = 20), 2 - celled, brown, clavate, substraight, formed near the septa, unilateral, antrorse. Ascomata up to 250 μm in diameter, superficial, subdense, dark brown, globose to subglobose, with a central ostiole. Peridium comprises hyaline inner cell and dark brown outer wall with textura angularis. Hamathecium with evanescent paraphyses. Ascospores 48–60 × 15–21 μm (x ̄ = 54 × 18 µm, n = 20), 3–4 seriate, cylindrical or oblong, hyaline when young, becoming dark brown when mature, 4 - septate, constricted at the septa, rounded at both ends, smooth-walled. Asexual morph: Phialides 40–30 × 5–9 μm (x ̄ = 35 × 7 µm, n = 10), opposite to unilateral, sometimes alternate, flask-shaped, few mixed with appressoria, ampulliform.

Notes.

Phylogenetic analyses showed that M. fusconigra forms a sister clade to M. aristolochiae-tagalae with strong statistical support (MLBS = 90 %), confirming their close evolutionary relationship (Fig. 1 View Figure 1 ). Both species share similarity in colony and peridium cell colour, orientation of appressoria, and shape of appressoria, ascomata, and ascospore ( Zeng et al. 2022). However, notable differences can be observed between M. fusconigra and M. aristolochiae-tagalae in the colour of superficial hyphae and the size of individual cells of superficial hyphae, appressoria, ascomata, ascospores, and phialides, and host species ( Zeng et al. 2022). This morpho-anatomical comparison with the phylogenetically allied species represents M. fusconigra as a distinct new species.