Pestalotiopsis alpinicola X. X. Luo & Jian Ma 2024, sp. nov.

Pestalotiopsis alpinicola X. X. Luo & Jian Ma sp. nov. Fig. 2 Type. China • Yunnan Province, Xishuangbanna Dai Autonomous Prefecture, Mengla County, Menglun Town, Tropical Botanical Garden, on diseased leaves of Alpinia zerumbet, 23 June 2022, X. X. Luo (holotype HJAUP M 1644.221; ex-type living culture HJAUP C 1644.221). Etymology. Referring to the host genus, Alpinia from which it was collected. Description. Leaf tip blight and irregular pallid leaf spots. Asexual morph on PDA: Conidiomata acervular, globose, 710–1110 μm diam., solitary or aggregated in clusters, black. Conidiophores indistinct and reduced to conidiogenous cells. Conidiogenous cells hyaline, smooth, cylindrical to ampulliform. Conidia fusiform, straight or slightly curved, 18.1–21.8 × 4.7–5.9 μm (x ̄ = 19.7 × 5.5 μm, n = 50), 4 - septate, slightly constricted at the septa; basal cell conical, 2.6–4.4 μm (x ̄ = 3.6 μm) long, hyaline or sometimes pale brown, smooth, thin-walled, with a single filiform appendage, unbranched, 3.6–6.2 μm (x ̄ = 5.1 μm) long; three median cells doliiform to cylindrical, smooth, 10–13 μm (x ̄ = 12 μm) long, concolorous or sometimes darker at the two upper cells, somewhat constricted at the septa, second cell from the base pale brown to brown, 3.5–4.5 µm (x ̄ = 4.1 μm) long, third cell brown, 3.3–4.2 µm (x ̄ = 3.8 μm) long, fourth cell pale brown to brown, 3.6–4.5 µm (x ̄ = 4.1 μm) long; apical cell conical to acute, hyaline, smooth, thin-walled, 3.1–4.5 µm (x ̄ = 3.6 μm) long, with 1–3 (mostly 2) filiform appendages, arising from the apical crest, unbranched, 13.1–20.9 µm long. Sexual morph not observed. Culture characteristics. Colonies on PDA grow fast, flat and spreading, growing all over the Petri dish after 2 weeks at 25 ° C in darkness, white, with flocculent aerial mycelium and entire edge, forming black conidiomata, and reverse pale straw. Additional specimen examined. China • Yunnan Province, Xishuangbanna Dai Autonomous Prefecture, Mengla County, Menglun Town, Tropical Botanical Garden, 23 June 2022, X. X. Luo. On diseased leaves of Alpinia zerumbet; paratype HJAUP M 1644.222, living culture HJAUP C 1644.222. Note. Two strains (HJAUP C 1644.221 and HJAUP C 1644.222) of Pestalotiopsis alpinicola isolated from leaf spots of Alpinia zerumbet clustered with P. lithocarpi (CFCC 55100 and CFCC 55893) with 95 % ML / 0.68 BI bootstrap support (Fig. 1). The ex-type strain HJAUP C 1644.221 is closely related to P. lithocarpi (CFCC 55100) and comparisons of their nucleotides showed 20 bp differences (2 %, including zero gap) nucleotide differences in three loci. Moreover, P. alpinicola is morphologically distinguished from P. lithocarpi Ning Jiang by its smaller conidia (4.7–5.9 μm vs. 6–7 μm) with shorter three median cells (10–13 μm vs. 12.5–14 μm) and fewer apical appendages (1–2 vs. 3–4) (Jiang et al. 2022).