Laccaria carminostipes Y. D. Xu & Z. M. He 2025, sp. nov.

Laccaria carminostipes Y. D. Xu & Z. M. He sp. nov. Figs 2 a – c, 3, 6 a, b Etymology. ‘ carminostipes ’ (Latin), referring to the carmine stipe surface. Diagnosis. L. carminostipes exhibits a red-brown to orange-brown, translucent-striate pileus, salmon-pink adnate lamellae, a carmine equalstipe, globose to subglobose echinulate basidiospores, and a loosely interwoven pileipellis. Type. China • Hunan Province: Sangzhi County, Badagongshan National Nature Reserve, at 29.65000°N, 109.695833°E, alt. 1742 m, in broad forest with trees of Fagaceae and bamboo, 29 July 2019, Z. H. Chen 31553 (MHHNU 31553, holotype). Description. Basidiomata small to medium-sized. Pileus 15–45 mm in diam, applanate to plano-concave, umbilicate, surface always fibrillose, sometimes missing, red-brown (7 B 6–7) to orange-brown (6 A 5–7), becoming darker with age, subhygrophanous; margin slightly translucent-striate. Lamellae adnate, distant, salmon-pink (7 A 3), narrow (about 2 mm high), entire, ventricose. Stipe 70–90 × 3–7 mm, central, equal, hollow, often slightly flexible, carmine (7 C 6–8); surface with indistinct to distinct whitish fibrillose coating; base with white (1 A 1) tomentum. Context thin, whitish (2 A 1) to brownish (5 A 2). Basidiospores [100 / 4 / 4] (6.5) 7–9 (9.5) × (6) 6.5–8 (8.5) μm, Q = (0.88) 0.96–1.18 (1.33), Qm = 1.04 ± 0.08, mostly globose to subglobose, sometimes broadly ellipsoid, inamyloid, cyanophilous, echinulate; spines up to 1 μm long, ≤ 1 μm broad at base, distant; hilar appendix 1.0–1.8 μm long, prominent, truncate. Basidia 38–46 × 10–13 μm, clavate, mostly 4 - spored, rarely 2 - spored; sterigmata 6–8 μm long. Pleurocystidia and cheilocystidia not seen. Lamellar trama regular to subregular, composed of filamentous hyphae 3–6 μm wide. Pileipellis a cutis; hyphae loosely interwoven, thin-walled, cylindrical, 8–10 μm wide, in place with erect ends, with a brownish (3 A 2) intracellular pigment. Stipitipellis a cutis, composed of parallel to interwoven, thin-walled, cylindrical hyphae 3–8 μm wide, with some exserted inflated ends. Clamp connections present in all parts of basidiomata. Ecology. Always gregarious, under the trees of Fagaceae, in montane coniferous and broad-leaved mixed forests; summer (Jul. – Aug.). Distribution. Known from the subtropical zones of China. Additional specimen examined. China • Hunan Province, Sangzhi County, Badagongshan National Nature Reserve, at 29.65000°N, 109.695833°E, alt. 1740 m, 29 July 2019, Z. H. Chen 31552 (MHHNU 31552); • Sangzhi County, Badagongshan National Nature Reserve, at 29.755000°N, 109.762500°E, alt. 1592 m, under trees of Fagaceae, 27 July 2020, Z. H. Chen 34706 (MHHNU 34706); • Yunnan Province, Jingdong Yi Autonomous County, Ailao Mountain, at 23.490278°N, 100.273333°E, alt. 2550 m, under trees of Quercus, 8 August 2024, P. Zhang 5444 (MHHNU 11944). Notes. Laccaria rubroalba and L. carminnostipes are characterized by medium-sized reddish basidiomata with a transluscent-striate pileus, but the former can be distinguished from the latter by having longer spines (1.2–2.7 μm long in L. rubroalba vs. up to 1 μm long in L. carminnostipes) and the presence of pleurocystidia and cheilocystidia (Luo et al. 2016). Laccaria cinnabarina J. Li & Y. Y. Cui is similar to L. carminnostipes by the reddish-brown stipes, but differs by its larger pileus (10–90 mm in L. cinnabarina vs. 15–45 mm in L. carminnostipes) and stronger spines (2 × 2 μm in L. cinnabarina vs. 1 × 1 μm in L. carminnostipes) (Li et al. 2024). Laccaria macrobasidia H. J. Cho & Y. W. Lim may sometimes be confused with L. carminnostipes, due to the similarity in size and color of their basidiomata. However, the two species can be differentiated based on the following diagnostic characteristics: basidiospores (9–11 × 8–10 μm in L. macrobasidia vs. 7–9 × 6.5–8 μm in L. carminnostipes), basidia (52–80 × 11–15 μm in L. macrobasidia vs. 38–46 × 10–13 μm in L. carminnostipes), pleurocystidia (present in L. macrobasidia, absent in L. carminnostipes), and the occurrence (L. macrobasidia in temperate forests, L. carminnostipes in subtropical forests) (Cho et al. 2020). According to our phylogenetical analysis (Fig. 1), L. carminostipes (Species 38) could be most closely related to L. fagacicola (Species 37), L. darjeelingensis (Species 36), and L. aurantiaca (Species 35). Laccaria fagacicola can be distinguished from L. carminostipes by the presence of abundant cheilocystidia (Cui et al. 2021). Laccaria darjeelingensis differs by its dull red pileus and possesses both pleurocystidia and cheilocystidia (Thapa et al. 2024). Laccaria aurantiaca displays longer spines (0.7–1.8 μm vs. ≤ 1.0 μm in L. carminostipes) and produces pleurocystidia and cheilocystidia (Tang et al. 2025). Our phylogenetic analysis shows the placement of the sample GMM 6585 within the clade of L. carminostipes (Species 38, 99 % BP, 1.00 PP, pairwise identity values of ITS = 99.84 %), suggest that this specimen might be L. carminostipes.