Acrocalymma guizhouense Q.Y. Shao, Y.F. Han & Z.Q. Liang, sp. nov. (Fig. 2)

MycoBank No.: MB843642

Type:— CHINA. Guizhou Province, Guiyang City, Guizhou University, the rhizosphere soil of potted Perilla frutescens (N 26°44′, E 106°67′), 29 August 2019, Q.Y. Shao, dried holotype HMAS 351907, ex-holotype CGMCC 3.208 53 (= GZUIFR H22.027).

Colonies on PDA attaining 31 to 33 mm in diameter after 14 days at 25°C, suborbicular, raised, dense, fluffy to velvety with smooth aspects, slightly undulate at the margin, white to light gray, absent pigment and exudates; reverse: black to light brown in the center, white at the margin. Colonies on OA 44 mm diameter after 14 days at 25°C, circular, slightly raised, sparse, fluffy, with a smooth edge, taupe; reverse: brown to light brown. Colonies on MEA attaining 27 to 28 mm diameter after 14 days at 25°C, suborbicular, slightly raised, fluffy, with irregular edge, white to pale yellow; reverse: orange to yellow. Vegetative hyphae septate, hyaline, smooth, 1.0–2.5 μm wide, thin walled with dumbbellshaped or guttulate content. Chlamydospores hyaline, smooth, subglobose or lageniform, with guttulate content, in short to long chains.

After 30 days of incubation at 25°C on PDA, the colonies almost covered the whole plate, fluffy, white to light brown, and black granular substances were visible. Through stereoscopic microscope (Motic China Co., Ltd, SZM-171) observation, these granular substances are pycnidia of this strain. Pycnidia 300–400 × 230–300 µm (av. = 353 × 250 μm, n = 10), semi-immersed to superficial, dark brown or black, globose or subglobose, separate but aggregated in clusters, papillate, with a central ostiole. Peridium 18–20 µm wide, composed of 5–8 layers of brown cells, arranged in a textura angularis, thick-walled, cells towards the inside hyaline to lightly pigmented, at the outside, darker. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 5–8 × 1.5–2.5 µm (av. = 6 × 2 μm, n = 20), discrete, cylindrical or lageniform, hyaline, formed from the inner layer cells of pycnidium wall. Conidia 9–13 × 1.5–2.5 µm (av. = 11 × 2 μm, n = 50), cylindrical to fusiform, unicellular, solitary, hyaline, smooth, straight, aseptate, thin walled with guttulate content, truncate at the base and becoming a little narrower at apex, one apex with small flabellate apical appendage. Sexual morph: Undetermined.

Etymology:— guizhouense, referring to Guizhou Province where the type locality was situated.

Additional specimens examined:— CHINA, Guizhou Province, Guiyang City, Guizhou University, N 26°44′, E 106°67′, from rhizosphere soil of potted medicinal plant Perilla frutescens, 29 August 2019, Q.Y. Shao. The dried cultures GZAC H22.028 and H22.029 and their living cultures GZUIFR H22.028 and GZUIFR H22.029 deposited in the Institute of Fungus Resources, Guizhou University, China (GZAC). The living cultures were kept in sterile 30% glycerol and deposited in a -80°C freezer.

Geographical distribution:— Guizhou Province, China.

Notes:— Phylogenetically, A. guizhouense clustered together with the other eleven known Acrocalymma in a clade with high support value, but formed a separated subclade (Fig. 1). Morphologically, among the known Acrocalymma species, A. Walkeri, A. pterocarpi and A. hongheense were observed to have sexual morph (Trakunyingcharoen et al. 2014, Jayasiri et al. 2019, Mortimer et al. 2021). In this study, three strains (CGMCC 3.208 53, GZUIFR H22.028 and GZUIFR H22.029) isolated from the rhizosphere soil of the potted Perilla frutescens only observed asexual morphs, but no sexual morph. Our strains tally with it being an Acrocalymma species in having globose, semi-immersed, ostiolate pycnidia, cylindrical or lageniform, hyaline conidiogenous cells and hyaline, smooth, guttulate, cylindrical to fusiform conidia (Trakunyingcharoen et al. 2014, Tennakoon et al. 2021). Acrocalymma guizhouense differs from the other species in having the narrowest conidia, with a width ranging from 1.5-2.5 µm. Therefore, morphological and molecular phylogenetic results indicated that these isolates are a new species in the genus Acrocalymma, described here as A. guizhouense.