Collybiopsis beijingensis R.L. Zhao & W.Q. Yang, 2025

Collybiopsis beijingensis R.L. Zhao & W.Q. Yang , sp. nov. Figure 2 View FIGURE 2 .

Fungal name: FN 572124

Diagnosis: The prominent features of this species include a greyish orange to brownish and medium-sized pileus; medium-sized basidiospores (6.4–8.9 × 3.3–3.9 µm) with ornamentation less developed; scattered to gregarious on rotting pine needles.

Holotype: China, Beijing, Miyun District, Bulaotun Town, Yunfeng Mountain , 28 August 2023, Bin Cao, Minyu Zhu and Bei Han, ZRL20234937 ( HMAS 282425 View Materials , GenBank accession-ITS: PQ408926, LSU: PQ40895 ).

Etymology: ‘ beijing ’ refers to the location ( Beijing)where the type specimen was collected.

Macroscopic description:— Pileus 14‒25 mm wide, shallowly depression to plane by maturity, wavy edges, surface smooth, dry, greyish orange (6B3) to brownish (7D8 to E8). Lamellae subdistant, L= 6–9, I= 1–3, almost free to adnate, in two major ranks with no anastomosis, whitish to yellowish white (3A2). Stipe 48–56 × 4‒5 mm, central to eccentric, cylindrical, when fresh reported as concolorous with pileus, apex yellowish white (3A2) to light brown (6D4), edge even. Context thin, white (3A2). Odor and taste not recorded.

Microscopic description:— Basidiospores 6.4–8.9(9.2) × (3.1) 3.3–3.9(4.5) µm, Q= 1.9–2.3, avQ = 2.1, broadly ellipsoid, amygdaliform, smooth, thin-walled, hyaline, non-dextrinoid, with drops. Basidia 23.6–26.5(32.6) × 4.1– 6.2(6.7) µm, 2 or 4 sterigmata, sterigmata 2.1–3.5 µm long, clavate, often constricted, sterigmata robust, slightly curved, oil droplets present. Cheilocystidia (25.2)30.1–36.7(37.7) × 4.5–6.3 (9.3) µm, broadly clavate, irregular, sometimes lobed, hyaline, thin-walled. Pleurocystidia (21.9)25.5–33.5 × (3.8)4.2–6.6 µm, abundant, clavate, subulate, sometimes lobed, contents homogeneous to heterogeneous with crystal-like inclusions, hyaline, firm-to thick-walled. Caulocystidia absent. Trama hyphae cylindrical, often sub-inflated, smooth, non-dextrinoid 1.7–5.8 µm wide. Pileipellis cylindrical, smooth, sometimes swollen, thin-walled, 2.2‒7.9 µm wide hyphae; Stipitipellis cylindrical, parallel along stipe, smooth, sometimes swollen, thin-walled, 2.4‒4.5 µm wide hyphae. Clamp connections present in all tissues.

Habitat and distribution: Scattered to gregarious on rotting pine needles in coniferous forest from summer to autumn.

Additional specimens examined: China, Beijing, Miyun District, Xinchengzi Town, Yunxiu Valley , 15 August 2023, Bin Cao, Min-yu Zhu and Bei Han, ZRL20232835 ; China, Beijing, Miyun District, Bulaotun Town, Yun feng Mountain , 28 August 2023, Bin Cao, Min-yu Zhu and Bei Han, ZRL20234938 ; China, Beijing, Mentougou District, Pearl Lake Scenic Area , 5 September 2023, Jia-xin Li, Wen-qiang Yang and Ze-zhi Wang, ZRL20232473 ; China, Beijing, Yanqing District, Luo jia tai Village , 18 August 2023, Jia-xin Li, Wen-qiang Yang and Ze-zhi Wang, ZRL20233443 .

Notes: Collybiopsis beijingensis can be easily distinguished by its greyish orange to brownish pileus. Microscopically, this new species has medium-sized spores with less developed ornamentation. In the field, this new species is morphologically similar to C. confluens ( Hughes & Petersen 2015) , which is known as a representative example of intra-specific variation between continents ( Kim et al. 2022). Collybiopsis confluens is distinguishable from C. beijingensis by its denser lamellae and larger cheilocystidia (34–77 × 2.5–4 µm) ( Hughes & Petersen 2015), which the two species are phylogenetically distant from each other. Collybiopsis ramealis is another morphological similar species to this new species. However, this known species has a smaller basidiocarp ( 2–20 mm), bigger basidiospores (7.8–11 × 2.5–4 µm) and different type of pileipellis ( Noordeloos 1983; Desjardin et al. 1997; Kim et al. 2022). In this study, phylogenetic analysis demonstrated that five specimens of this new species formed a cohesive cluster with full support ( Fig 1 View FIGURE 1 ). Additionally, they were sister to C. peronata ( Fig 1 View FIGURE 1 ). Collybiopsis peronata fewer and buff lamellulae (1–3), a thicker stipe ( 3–8 mm), longer basidia (20–40 µm), and longer cheilocystidia (25–90 × 5–10 µm) ( Noordeloos et al. 1999; Kim et al. 2022).