Index Fungorum number: IF 900644; Facesoffungi number: FoF 15295; FIGURE. 4

Etymology: Referring to the host plant Berchemia polyphylla var. leioclada, on which the fungus was collected

Holotype: KUN-HKAS 131985

Endophytic in fresh leaves of Berchemia polyphylla var. leioclada. Sexual morph: not observed. Asexual morph: Conidiomata pycnidial in culture on PDA, globose or irregular, brown to dark brown, solitary or in groups, embedded, erumpent, white to cream conidial drops exuded from ostioles. Conidiomatal wall brown to dark brown, composed of several layers of brown to dark brown cells of textura angularis. Conidiophores 9–17 × 2–3 µm (x = 12.9 × 2.3μm, n = 25), cylindrical to subcylindrical, tapering to straight towards the apex, 1–2 septate, densely aggregated, hyaline, subhyaline to pale brown at the base, smooth-walled. Conidiogenous cells phialidic, terminal, cylindrical to subcylindrical, hyaline. Alpha conidia 5–6 × 1.5–2.5 µm (x = 5.6 × 2μm, n = 32), ellipsoidal to obovoid, or fusoidellipsoid, rounded or subobtuse at apex, acutate or subtruncate at the base, hyaline, aseptate, smooth-walled, with 0-1 small-guttules. Beta conidia 19–26 × 1–1.5 μm (x = 22.4 × 1.3μm, n = 30), filiform, slightly curved, tapering towards the ends, aseptate, hyaline, not guttulate. Gamma conidia not observed.

Cultural characteristics: Cultures on MEA initially white, growing slowly and entirely covering the 9cm Petri dish after 14 days, velvety appearance with whit aerial mycelium, white on surface, white to pale brown on reverse.

Material examined: CHINA, Guizhou Province, from Berchemia polyphylla var. leioclada leaves, 27 June 2022, S.X. Zhou, A12J-1 (KUN-HKAS 131985, holotype), ex-type culture GMBCC 20000.

GenBank numbers: ITS = PP049022, HIS3 = PP056095, TEF1-α = PP056096, TUB2 = PP056097.

Notes: In our phylogenetic analysis, Diaporthe berchemiae formed a distinct lineage between D. ellipsospora and the clade of D. nanjingensis and D. jinxiu (FIGURES. 5, S 2). Diaporthe ellipsospora was introduced based on the sexual morph (Dissanayake et al. 2020), while D. berchemiae is reported by the asexual morph. Therefore, we are unable to compare the morphology between these two species, but phylogenetically they are distinct (Figures 5, S 2). The comparison of ITS region between D. berchemiae and D. ellipsospora revealed 41 bp (7.9%) differences which strongly support our new isolate as a new species.

Diaporthe berchemiae is similar to D. jinxiu and D. nanjingensis in having hyaline, cylindrical, smooth-walled conidiophores, phialidic, cylindrical conidiogenous cells, and hyaline, aseptate, ellipsoidal alpha conidia. However, D. berchemiae differs from D. jinxiu and D. nanjingensis in having 0-1 small-guttulate alpha conidia, whereases, the conidia of D. jinxiu and D. nanjingensis with two large guttules. In addition, the alpha conidia of D. jinxiu are rounded at both ends, while the alpha conidia are rounded or subobtuse at the apex and acutate or subtruncate at the base in D. berchemiae (Wang et al. 2021). Diaporthe berchemiae has much shorter beta conidia (19–26 vs. 29.7–37.1(-39.7) um) than those of D. nanjingensis and the conidiogenous cells of D. nanjingensis are muti-guttulate, which were not observed in D. berchemiae (Wan et al. 2023). The PHI test revealed no significant recombination event between Diaporthe berchemiae and the closely related taxa (Φw = 0.22) (FIGURE. 6). Therefore, we introduce our new isolate as a new species based on both phylogeny and morphological analyses.