Samsoniella aggestitenuipes Q. Y. Dong & S. Y. Gao 2026, sp. nov.

Samsoniella aggestitenuipes Q. Y. Dong & S. Y. Gao sp. nov. Fig. 3 Etymology. The epithet aggestitenuipes combines aggesti -, from Latin aggestus, referring to the conidial accumulation, with tenuipes, from Cordyceps tenuipes, reflecting a morphology similar to C. tenuipes but distinguished by synnematal branches that bear massive conidial aggregates. Holotype. China, • Sichuan Province, Chengdu City, Qionglai City, Tiantaishan County, isolated from the pupa of Lepidoptera, 21 August 2024, Quanying Dong (holotype CXAC 0015; ex-holotype living culture, CXCC 0015). Sexual morph. Undetermined. Culture characters. Conidial arrangement Isaria - like. Synnemata two or several, on the pupae of Lepidoptera buried in soil, white, up to 1.8–2.7 cm long. Stipes cylindrical, 0.6 mm wide, producing a mass of conidia at the branches of synnemata, powdery. Colonies on PDA attaining a diameter of 49–52 mm in 21 days at 25 ° C, white to cream-colored, soft cottony aerial mycelium, reverse pale yellow. Hyphae smooth-walled, branched, septate, hyaline, 1–2 µm wide. Synnemata arising from the middle body of pupae were irregularly branched, 1.8–2.7 cm long, 0.3–0.6 mm wide; cylindrical or clavate stipes with powdery white heads. Cultures readily produced phialides and conidia after 1 week on potato dextrose agar at 25 ° C showing a granular appearance due to profuse conidiation. Conidiophores cylindrical or clavate, hyaline, smooth-walled, simple to verticilate form 1–3, 5–10.5 × 2–2.5 µm, 1–2 µm wide (base), 2–2.5 µm wide (apex). Phialides from aerial mycelium straight to slightly flexuose, solitary or in whorls of two to four on each branch, cylindrical to flask-shaped, usually with a slightly swollen basal part, 6–28 × 1–2.5 µm, tapering gradually or abruptly from 1–2 µm (base) to 0.5–1.5 µm (apex). Conidia hyaline, subglobose, ovoid, or fusiform, smooth, one-celled, 2–4 × 1.5–2.5 µm, usually in chains. Other material examined. China, • Sichuan Province, Chengdu City, Qionglai City, Tiantaishan County, on the pupa of Lepidoptera, 21 August 2024, Quanying Dong (paratype CXAC 0016; ex-paratype living culture CXCC 0016). Host. Lepidoptera pupa. Known distribution. Sichuan Province, China. Commentary. Samsoniella aggestitenuipes displays typical genus-level characteristics such as solitary or whorled phialides and conidia varying from subglobose to ovoid or ellipsoid. It is distinguished by the following unique combination of morphological characteristics: phialides solitary or in whorls of 2–4, cylindrical, 6–28 × 1–2.5 µm; conidia mostly subglobose, ovoid, or fusiform, 2–4 × 1.5–2.5 µm, usually aggregated in chains. Furthermore, the species was isolated from a Lepidoptera pupa. Phylogenetically, S. aggestitenuipes is strongly supported (BS = 93 %, PP = 0.88) and clusters with S. coleopterorum and S. pseudogunnii, but it is distinguished from these two species by forming a separate clade within this group (Fig. 1). Morphologically, these two species differ from S. aggestitenuipes in the following ways. Samsoniella coleopterorum, a species described from China, has aculeate and relatively shorter phialides measuring 5.4–9.7 × 1.2–1.8 μm and smaller conidia, 1.7–2.5 × 1.2–1.8 μm vs. 2–4 × 1.5–2.5 µm (Chen et al. 2020). Samsoniella pseudogunnii, a species described from Guiyang, Guizhou Province, and also similar to S. aggestitenuipes in appearance, has relatively shorter phialides (6.8–11 × 2.2–2.4 µm vs. 6–28 × 1–2.5 µm) and relatively smaller conidia (2.8–3.2 × 1.7–2.1 µm vs. 2–4 × 1.5–2.5 µm) (Chen et al. 2021).