Colletotrichum poalesicola Norph. & X. C. Wang 2025, sp. nov.

Colletotrichum poalesicola Norph. & X. C. Wang sp. nov. Figs 4, 5 Etymology. The epithet refers to “dweller on Poales,” utilizing the Latin suffix - cola, meaning “inhabitant” or “dweller.” Type. China • Guizhou Province, Zunyi City, Symptomatic leave of Poaceae sp. (bamboo), 2024.03. 02, coll. Wang Xingchang, Rz 1-2 / GZ 28-1/28-2 (dried culture, HGUP 25-0041, holotype), ex-type living culture GUCC 25-0040. Description. Isolated from bamboo. Sexual morph: Not observed. Asexual morph: Conidiomata pycnidial, globose, dark brown, superficial on PDA, releasing conidia in a yellow mass, slimy, globose. Conidiophores either directly formed from hyphae or from a cushion of spherical hyaline cells, septate, and branched. Conidiogenous cells hyaline to pale brown, cylindrical to clavate, straight to flask-shaped, (17 –) 18–40 (– 53) × (3 –) 4–5 (– 5.8) μm (mean ± SD = 33 ± 0.9 × 4 ± 0.3 μm). Setae not observed. Conidia (12 –) 12.5–14 (– 15) × (6 –) 6.5–7.5 (– 8.5) μm (mean ± SD = 13 ± 0.8 × 7 ± 0.2 μm), n = 50, L / W ratio = 2.2, hyaline, aseptate, smooth-walled, ellipsoidal to cylindrical, one end rounded and one end acute or both ends rounded, guttulate, granular. Culture characteristics. Colonies on PDA reach 7–9 cm in diameter after 7 days at room temperature (± 25 ° C), exposed to 12 hours of light and 12 hours of darkness. The colonies are rhizoid to filamentous, dense, with a cottony or floccose surface and a filamentous margin. After 14 days, the colony appears white from above, producing grouped black and yellow pycnidia with orange conidial mass in the center and a white to pale-yellow reverse (Fig. 5 a, b). Material examined. China • Guizhou Province, Zunyi City, Symptomatic leaves of Poaceae sp. (bamboo), 2024.03. 02, coll. Wang Xingchang, Rz 1-2 / GZ 28-1/28-2 (dried culture, HGUP 25-0041, holotype), ex-type living culture GUCC 25-0040, GUCC 25-0057. Notes. Phylogenetic analyses based on multi-locus sequence data place Colletotrichum poalesicola within the C. boninense species complex, forming a distinct clade closely related to C. boninense sensu stricto with support of 61 % BSML, 51 % BSMP, and 0.75 BYPP (Fig. 1). Morphologically, C. poalesicola can be readily distinguished from its closest relatives by the dimensions and shape of its conidia. The conidia of C. poalesicola are shorter and broader, measuring (12 –) 12.5–14 (– 15) × (6 –) 6.5–7.5 (– 8.5) µm, compared to those of C. boninense, which are more narrowly ellipsoidal [(11.5 –) 13–15.5 (– 17) × (4 –) 5–6 (– 7) µm] (Moriwaki et al. 2003). Molecular differentiation is further supported by pairwise sequence comparisons between C. poalesicola and the type strain of C. boninense, which revealed notable base pair differences across multiple loci: ITS = 1 / 533 (0.18 %), gapdh = 4 / 251 (1.59 %), chs- 1 = 27 / 271 (9.96 %), act = 1 / 269 (0.37 %), β-tubulin = 1 / 495 (0.20 %), his 3 = 0 / 387 (0 %), and cal = 0 / 424 (0 %). The high level of divergence observed in the chs- 1 locus, in particular, provides strong molecular evidence for species delimitation. Moreover, results from the PHI recombination test revealed no significant recombination among C. poalesicola and C. boninense (Φw> 1.0; Fig. 4), further corroborating their genetic distinctiveness and independent evolutionary trajectory. In conclusion, the combination of robust phylogenetic support, consistent morphological differences, and significant molecular divergence justifies the recognition of Colletotrichum poalesicola as a novel species within the C. boninense species complex.