Leptobacillium doupengense W. K. Lin, Y. M. Zhou & L. L. Lou 2026, sp. nov.

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Leptobacillium doupengense W. K. Lin, Y. M. Zhou & L. L. Lou sp. nov. Fig. 3 Etymology. The specific epithet refers to Doupengshan Scenic Area, the locality where the species was collected. Type. China, • Guizhou Province, Qiannan Buyi and Miao Autonomous Prefecture, Duyun City, Doupengshan Scenic Area (26°22'17"N, 107°23'31"E), from humus substrates accumulated within tree holes, October 2024, collected by Wen-Kai Lin (holotype: GZUIFR DPS 001, dried culture specimen; ex-type culture: GZUIFR DPS 003, derived from the holotype material). Description. Sexual morph: Not observed. Asexual morph: On PDA after 14 days at 25 ° C, colonies reached 35–40 mm in diameter. Colony surface white, raised, circular with entire margin, mycelium velvety to floccose, reverse smooth, pale yellow, orange-yellow to cream-yellow, with yellow pigment diffusing into the agar. Hyphae septate, hyaline, smooth-walled, 1–2 μm wide. Conidiophores arising from aerial hyphae, hyaline, septate, smooth-walled. Phialides mostly solitary, rarely verticillate, borne terminally on conidiophores or lateral branches, 15–23 × 1.8–2.2 μm (n = 30), tapering toward the apex. Conidia formed in slender chains, hyaline, fusiform to narrowly cylindrical, 3–4 × 0.5–1 μm (mean = 3.5 × 1.0 μm, n = 30). Chlamydospores absent. Habitat. On humus substrates collected from tree holes of unidentified tree species. Distribution. China, Guizhou Province, Qiannan Buyi and Miao Autonomous Prefecture, Duyun City. Notes. Phylogenetic analyses based on multi-locus sequence data revealed that Leptobacillium doupengense forms a distinct and well-supported clade. Phylogenetically, L. doupengense is placed in a subclade with L. coffeanum, L. symbioticum, L. filiforme, and L. xianyushanense. Pairwise sequence comparisons in the ITS region revealed that L. doupengense differs from L. coffeanum (COAD 2057) by 28 bp with 4 gaps (93.9 % similarity), from L. filiforme (URM 7918) by 25 bp with 3 gaps (94.6 %), from L. symbioticum (NBRC 113865) by 22 bp with 1 gap (95.2 %), and from L. xianyushanense (RCEF 6793) by 15 bp with 1 gap (96.7 %). Species delimitation in this study was based on an integrative taxonomic approach, including an independent and well-supported placement in the multi-locus phylogeny, ITS sequence divergence from closely related species, and diagnosable morphological differences. Morphologically, L. doupengense is similar to most species of Leptobacillium in producing long, slender chains of conidia. However, it can be distinguished from its closely related species by several morphological characteristics. Compared with L. coffeanum, L. doupengense produces conidia arranged in chains, whereas the conidia of L. coffeanum are produced in slimy heads (Gomes et al. 2018). Although L. doupengense is morphologically similar to L. xianyushanense, it differs from the latter in colony growth and colony surface morphology. On PDA at 25 ° C after 14 days, colonies of L. doupengense reached 35–40 mm in diameter and were slightly raised, smooth, and circular, without obvious divergent cracks. In contrast, colonies of L. xianyushanense grow more slowly, reaching 20–36 mm in diameter after 14 days at 25 ° C, and have a white, irregular floccose surface characterized by divergent cracks. Additionally, L. doupengense tends to produce shorter conidia (3–4 × 0.5–1 μm) than L. symbioticum (4.0–6.9 × 0.7–1.6 μm), L. filiforme (7.2–12.5 × 1.0 μm), and L. xianyushanense (3.8–5.6 × 0.5–1.2 μm) (Okane et al. 2020; Chen et al. 2021; Chang et al. 2024). Therefore, the combination of colony morphology, conidial size, ITS sequence divergence, and independent phylogenetic placement supports the recognition of L. doupengense as a distinct species within Leptobacillium.

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