Acrocalymma poaceicola Tennakoon & S. Hongsanan, 2025

Acrocalymma poaceicola Tennakoon & S. Hongsanan , sp. nov.

Fig. 7 View Figure 7

Etymology.

Named after the host family ( Poaceae ) where this fungus was collected.

Holotype.

SZU 25-015 .

Description.

Saprobic on a dead leaf of Arundo pliniana ( Poaceae ). Sexual morph: Undetermined. Asexual morph: Conidiomata 60–70 × 80–110 µm ( x ̄ = 64 × 97 μm, n = 10), pycnidial, dark brown to black, solitary or clustered, immersed to semi-immersed, erumpent through host surface, unilocular, globose to subglobose, ostiolate. Conidiomatal wall 15–20 μm wide ( x ̄ = 17 μm), 3–4 layers of irregular cells arranged in a textura angularis, cells towards the inside hyaline, at the outside, light brown, thick-walled. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 5–10 × 2.5–5 µm ( x ̄ = 7.3 × 3.2 μm, n = 20), phialidic, hyaline, smooth, ampulliform to doliiform, proliferating with visible periclinal thickening at apex. Conidia 24–32 × 6–7.2 µm ( x ̄ = 30 × 6.8 μm, n = 20), hyaline, cylindrical with an obtuse apex, protuberant and with a rounded hilum at base, straight, aseptate, guttulate, smooth-walled, bearing a mucilaginous appendage (2–2.5 µm diam.) at the apex.

Material examined.

China • Yunnan Province, Kunming , on a dead leaf of Arundo pliniana ( Poaceae ), 12 July 2017, D. S. Tennakoon, DST 010 ( SZU 25-015 , holotype) • ibid. 21 July 2017, DST 015 ( SZU 25-016 , paratype) • ibid. 15 August 2017, DST 017 ( SZU 25-017 , paratype) .

Notes.

The morphology of our collection ( SZU 25-015 , SZU 25-016 , and SZU 25-017 ) tallies with Acrocalymma species in having pycnidial conidiomata, hyaline, ampulliform to doliiform conidiogenous cells, and aseptate, cylindrical to fusoid conidia ( Zhang et al. 2012; Hyde et al. 2013; Mortimer et al. 2021; Tennakoon et al. 2021). According to the multi-gene phylogeny (LSU, SSU, and ITS) here, our collection clusters with A. bilobatum isolates ( MFLUCC 20-0125 and K. L. Chen L 119) with 87 % ML and 0.95 BYPP statistical support. In addition, our collection isolates group together with 100 % ML and 1.00 BYPP statistical support. Our collection can be distinguished from A. bilobatum in having smaller conidiomata (60–70 × 80–110 µm vs 170–275 × 135–205 µm) and larger conidia (24–32 × 6–7.2 µm vs 7–12 × 2.5–4 µm) with bearing a mucilaginous appendage ( Calabon et al. 2023). A comparison of the 524 nucleotides across the ITS (+ 5.8 S) gene region of our collection ( SZU 25-015 ) and A. bilobatum ( MFLUCC 20-0125 ) shows 12 base pair differences (2.29 %). Therefore, we recognize that these three isolates belong to one species, which we introduce as a new species herein.