Leccinum septentrionale Y. Gao & C.L. Hou., 2024

Leccinum septentrionale Y. Gao & C.L. Hou. , sp. nov. ( Figs. 3 View FIGURE 3 , 4 View FIGURE 4 )

MycoBank: MB 851695

Diagnosis: —Characterized by pileus sub-hemispherical to plano-convex, yellowish-brown to brown when mature, surface tomentose, with dirty orange maculae; hymenophore surface grayish yellow to light grayish orange, not changing color when bruised. Basidiospores 12–20 × 4.7–7.5 μm. Basidia 24–40 × 10–17 μm.

Typification: — CHINA. Beijing: Yanqing District, Songshan (WGS84 coordinates: 115.45, 40.31, elevation 1211 m), associated with Pinus tabulaeformis Carriere and Quercus L., 23 August 2017, C.L. Hou. & J.Q. Li (holotype BJTC 113). GenBank: ITS = PP941787; LSU = PP941793; rpb2 = PP942346; tef1-α = PP942352.

Etymology: —The epithet “septentrionale ” refers to “northern China ” where the holotype was collected.

Basidiomata small to medium-sized. Pileus 3.5–6 cm in diam., sub-hemispherical to convex when young, plano-convex to applanate when mature; yellowish to slightly dirty orange (#d49d7e) when young, yellowish-brown (#b79980) to brown (#6e553f) when mature; surface tomentose, sometimes with dirty orange (#ce8e6b) maculae, dry but not glutinose, margin slightly dehisce, soft orange (#f1c679); context 5–13 mm thick in the center of pileus, white (#ffffff) to cream (#fffdd0) or dark yellow (#997e1c) to grayish white (#ada37d), not changing color when bruised; Hymenophore adnate to emarginate around apex of stipe; surface grayish yellow (#c0b697) to light grayish orange (#ded8c8), not changing color when bruised; pores subangular to roundish, 0.4–1 mm wide; tubes up to 18 mm long, concolor with hymenophore, not changing color when bruised. Stipe 5–10 × 0.7–1.5 cm, clavate to subcylindrical, always enlarged downwards; surface white (#ffffff), covered with dark brown (#2a1c0e) scabrous squamules, not changing color when bruised; context whitish (#f7f5f3), basal mycelium white (#ffffff), without color change when injured. The edibility is unknown.

Basidiospores (140/3/3) 12–20(–23) × 4.7–7.5(–8) μm, Q = 1.9–3.7, Q m = 2.7 ± 0.23, subfusiform to fusiform with slight suprahilar depression, smooth, thin-walled, with a large oleiferous guttule, or several guttules, hyaline to yellowish in H 2 O and KOH, yellowish in Melzer’s Reagent. Basidia (17–)24–40(–44) × 10–17 μm, clavate, 4-spored, hyaline to yellowish in H 2 O and KOH solution, yellowish in Melzer’s Reagent. Hymenophoral trama boletoid, hyphae subcylindrical, 3.5–9 μm wide, hyaline to yellowish in H 2 O and KOH solution, non-amyloid. Cheilo- and pleurocystidia 39–70 × 7–20 μm, abundant, subfusiform to fusiform, thin-walled, yellowish in H 2 O and KOH, brownish yellow in Melzer’s Reagent. Pileipellis a trichoderm composed of vertically arranged, subcylindrical, 3–9.5 μm wide hyphae, hyaline to yellowish brown in H 2 O and KOH solution, yellowish to brownish yellow in Melzer’s Reagent. Pileal trama made up of 3.5–13 μm wide filamentous hyphae, thin-walled, hyaline to yellowish in H 2 O and KOH, yellowish in Melzer’s Reagent. Clamp connections absent in all tissues.

Habit and habitat: —Solitary, scattered, or gregarious on the ground in mixed coniferous and broad-leaved forest dominated by Quercus and Pinus .

Additional specimens examined: — CHINA. Beijing:Yanqing District, Songshan (WGS84 coordinates: 115.49333, 40.3752778, elevation 1198 m), associated with Pinus tabulaeformis Carriere and Quercus L. spp., 17 August 2023, Hao Zhou, Yue Gao & Xin Tong (BJTC Z1642); CHINA. Beijing: Huairou District, Labagoumen (WGS84 coordinates: 116.45056, 40.9586111, elevation 1272 m), associated with Acer pictum Thunb. , 25 August 2020, Hao Zhou, X.Y. Shen & X.B. Huang (BJTC Z1235); CHINA. Beijing: Huairou District, Labagoumen (WGS84 coordinates: 116.46778, 41.0569444, elevation 1268 m), associated with Acer pictum Thunb. , 13 September 2023, Hao Zhou, Yue Gao & Xin Tong (paratype BJTC Z1662); CHINA. Beijing: Mentougou District, Baihua Mountain (WGS84 coordinates: 115.58361, 39.8366667, elevation 1216 m), associated with Quercus mongolica Fisch. ex Ledeb. , 22 August 2022, C.L. Hou, Hao Zhou, X.N. Sui & H.F. Yan (BJTC Z1536); CHINA. Beijing: Mentougou District, Baihua Mountain (WGS84 coordinates: 115.55778, 40.8138889, elevation 1223 m), associated with Quercus mongolica Fisch. ex Ledeb. , 16 August 2023, Hao Zhou, Yue Gao & Xin Tong (BJTC Z1638).

Commentary:— Leccinum septentrionale generally shares similar colors of hymenophore with Leccinum phaeocarpum P.M. Wang, X. Meng, Zhu L. Yang & Yan C. Li , however L. phaeocarpum , originally described from China, differs from L. septentrionale in its brown to pale brownish or even dirty white pileus, white stipe context staining greenish blue at the base when injured, and relatively small basidia measuring 24–33 × 8–12 µm ( Wang et al. 2023). Leccinum griseonigrum A.H. Sm., Thiers & Watling also has slender stems, but it changes blue when its white pileal context injured, has an avellaneous to dingy cinnamon-buff pileus, and has relatively small basidiospores measuring 13–16 × 4–5.5 µm ( Smith et al. 1967). Leccinum scabrum differs from L. septentrionale in its wrinkled and smoke-grey pileus, pale white hymenophore, turn pinkish when injured, and pale white basidiospores ( Gray et al. 1821; 1832; den Bakker & Noordeloos 2005). Leccinum pseudoborneense X.Meng & Yan C. Li & Zhu L. Yang also has pale brown to dark brown pileus, but its stipe staining asymmetric blue when injured ( Meng et al. 2021). Phylogenetically, L. septentrionale is related to Leccinum album X. Meng, Yan C. Li & Zhu L. Yang in the analyses of the multi-loci and ITS datasets, respectively ( FIGS. 1 View FIGURE 1 and 2 View FIGURE 2 ). However, L. album differs from L. septentrionale in its entirely white pileus, the white hymenophore staining indistinct greenish blue when injured, and the white stipe context always changing greenish blue at the base when injured ( Meng et al. 2021).