Sebacina orientalis H. Suh, D. Kim & Y. W. Lim 2026, sp. nov.

Sebacina orientalis H. Suh, D. Kim & Y. W. Lim sp. nov. Fig. 8 Diagnosis. Basidiomata mainly develop on dead branches. The basidiomata surface is white to milk-white with yellowish spots. Holotype. REPUBLIC OF KOREA, Gangwon State, Yanggu-gun, Yanggu-eup, Yanggu Arboretum, on a dead branch, 08 September 2023. SFC 20230908-13 (dried specimen). Etymology. From orientalis – eastern in Latin, referring to the eastern origin of the species. Description. Basidiomata fully resupinate, attached firmly to the substrate, young basidiomata growing on stems of shrubs and dead branches, encrusting everywhere when old, forming thin patches on the substrate. Surface smooth, dull, white (1 A 1) to yellowish white (4 A 2), consistency wax-like, cartilaginous. Margin irregularly thinning out and distinctly bounded. Basal hyphal system monomitic, subicular hyphae thick-walled, septate with frequent branching, hyaline, without clamp connections, 3.0–4.3 μm thick. Basidiospores elliptical or allantoid, hyaline, smooth, IKI-, CB-, (7.1 –) 9.0–11.6 (– 12.6) × (5.8 –) 6.1–7.6 (– 8.5) μm with granular contents (L = 10.3 μm, W = 7.1 μm, Q = 1.4, n = 31 / 2). Resting spores usually observed, thick-walled, irregularly shaped. Dikaryophyses coralloid, flagelliformed, and tinily ramified, derived from the same hyphae with basidia. Probasidia globose to subglobose, mature basidia elliptical or pyriform, longitudinally septate, 13.1–17.3 × 7.5–11.8 μm, usually containing oil drops, with elongated four sterigmata, average 2.5 μm width, up to 16.0 μm long, blunt at the apex. Cystidia absent. Distribution. REPUBLIC OF KOREA. Additional specimens examined. REPUBLIC OF KOREA, Gangwon State, Yanggu-gun, Gwangchi National Recreation Forest, on a tree, 16 August 2023, SFC 20230816-55; REPUBLIC OF KOREA, Gangwon State, Yanggu-gun, Yanggu-eup, Yanggu Arboretum, on a rotten leave, 17 August 2023, SFC 20230817-43; Republic of Korea, Gangwon State, Yanggu-gun, Gwangchi National Recreation Forest on a rotten branch, 07 September 2023, SFC 20230907-02; REPUBLIC OF KOREA, Gangwon State, Yanggu-gun, Gwangchi National Recreation Forest, on a rotten branch, 07 September 2023, SFC 20230907-03; REPUBLIC OF KOREA, Gangwon State, Yanggu-gun, Yanggu-eup, Yanggu Arboretum, on a rotten rotten leave, 08 September 2023, SFC 20230908-04; REPUBLIC OF KOREA, Gangwon State, Yanggu-gun, Yanggu-eup, Yanggu Arboretum, on a rotten leave, 08 September 2023, SFC 20230908-05; REPUBLIC OF KOREA, Gangwon State, Yanggu-gun, Yanggu-eup, Yanggu Arboretum, on a rotten leave, 08 September 2023, SFC 20230908-19. Notes. Sebacina orientalis is phylogenetically close to S. incarnata. The two species can be distinguished by the color of the basidiomata surface: S. orientalis is white (1 A 1) to yellowish white (4 A 2), whereas S. incarnata is pale orange (6 A 3) to pastel red (7 A 3). GenBank accession numbers. ITS (PV 399937, PV 399941, PV 399944 – PV 399945, PV 399948 – PV 399950, PV 399952 – PV 399953), LSU (PV 399899, PV 399903, PV 399906 – PV 399907, PV 399910 – PV 399912, PV 399914 – PV 399915), rpb 2 (PV 417258 – PV 417262).