Scleroderma erubescens
Scleroderma erubescens Z.W. Ge, R. Wu & L.-R. Zhou
MycoBank Number: MB 847686
Basidiomata epigeous, 10–20 mm in diam., 12–35 mm tall; upper part globose to subglobose, turning reddish purple to blackish red (11D5) when bruised. Peridium is leathery, thin, roughly 0.5 mm thick, intact at the early stage, irregularly rupturing at the apex at maturity. Surface is light yellow (5C5), brownish yellow (5E7), and pale yellow (3B4); becoming brown (5E6) to earthy brown (5D6) when dried, cracked into tiny squamules, exposing the whitish inner layer, fading to yellow white (3A2) toward the gleba. Gleba firm, gray–white (4C7) when young, turning gray–black (3E1) with age. Pseudostipe subcylindrical, 3–15 mm high, 3–15 mm in diam., pinched or folded at base, attached to the substrate via aggregated white rhizomorphs. Basidiomata epigeous, 10–20 mm in diam., 12–35 mm tall; upper part globose to subglobose, turning reddish purple to blackish red (11D5) when bruised. Peridium is leathery, thin, roughly 0.5 mm thick, intact at the early stage, irregularly rupturing at the apex at maturity. Surface is light yellow (5C5), brownish yellow (5E7), and pale yellow (3B4); becoming brown (5E6) to earthy brown (5D6) when dried, cracked into tiny squamules, exposing the whitish inner layer, fading to yellow white (3A2) toward the gleba. Gleba firm, gray–white (4C7) when young, turning gray–black (3E1) with age. Pseudostipe subcylindrical, 3–15 mm high, 3–15 mm in diam., pinched or folded at base, attached to the substrate via aggregated white rhizomorphs. Basidiospores [100/5/3] (6.5–) 7.0–11.0 (–12.0) µm in diam. (not including ornamentation), 9.0 µm on average; globose, rarely subglobose, echinulate; gray–black to dark brown (2F5) in KOH; spiny under LM and SEM, and ornamentation 1.0–3.0 µm high (Figure 3A–C and Figure 4A–C). Peridium composed of subcylindric hyphae, evenly and tightly arranged, from light yellow (3B3) to earthy brown (5D6), often inflated at the septa, hyphae from the peridium toward the gleba light yellow (5A2). Gleba made up of globose to moniliform expanded cells measuring 2.0–5.0 µm. Hyphae of rhizomorphs bifurcating. Clamp connections present on gleba hyphae.
Habit and Habitat: Solitary, scattered to gregarious on soil in forests intermixed by Castanea spp., Carya illinoinensis, and Pinus spp.
Additional specimens examined: CHINA. Yunnan Province: Nujiang Lisu Autonomous Prefecture, Fugong County, Shiyueliang Township, 3 August 2011, X.T. Zhu 363 (KUN-HKAS 73740, paratype), alt. 1700 m; Baoshan City, Longyang District, Taibaoshan Forest Park, in a forest dominated by Pinus yunnanensis and Castanea spp.; 17 September 2019, Z. W. Ge 4356 (KUN-HKAS 126622, paratype), alt. 1700 m.
Notes: Scleroderma erubescens is characterized by its small basidiomata turning reddish purple to blackish red after injury and basidiospores with irregular spiky ornamentation. Scleroderma verrucosum, originally described from France, forms the sister species to S. erubescens. Both species have thin peridium covered with tiny squamules and conspicuous echinulate basidiospores. However, S. erubescens has smaller basidiomata, which turn reddish purple to blackish red after injury, and a thinner peridium and hyphae with clamp connections. In addition, S. erubescens has smaller basidiospores and slightly longer spines (measuring 1.0–3.0 µm). Scleroderma erubescens is also similar to S. nitidum, originally described from Nepal, in having small basidiospores and basidiomata with thin, yellowish brown peridium, and echinulate basidiospores [43]. However, S. nitidum is sessile (or only has small pseudostipe), lacks clamp connections, and its mature gleba is dark purpuraceous or grayish brown. Scleroderma texense Berk., originally described from Texas, USA, resembles S. erubescens by the sizes of the basidiospores and the presence of clamp connections. However, S. texense has subreticulate basidiospores, a rubescent endoperidium, and the mature basidiomata have a strongly squamulose surface [43]. In addition, the basidiomata of S. erubescens are smaller than those of S. texense (60–100 mm diam.). Scleroderma areolatum, originally described from Germany, is another species similar to S. erubescens by having spiny basidiospores, sessile or sharply stipitate basidiomata, and dehiscence through an irregular, lacerate apical pore, whitish to dark reddish brown gleba, strongly rubescent context, and the absence of clamp connections. However, the basidiospores of S. erubescens are smaller than those of S. areolatum (9–) 10–15 (–18) µm diam.), and the peridium of S. erubescens turns reddish purple to blackish red when bruised. Scleroderma cepa, originally described from Europe, is also similar to S. erubescens in sizes of basidiospore ornamentation, but has larger basidiospores measuring (7–) 8–13 (–14) µm, sessile or pseudostipitate basidiomata, stellate dehiscence, and the absence of clamp connections. In addition, the peridium of S. erubescens is thicker, and its basidiomata turn reddish purple to blackish red when bruised.
Fig. 1 Phylogenetic tree inferred from maximum likelihood (ML) analysis based on the dataset of ITS sequences of Scleroderma species. The ML bootstrap numbers (MLB) ≥ 50% and Bayesian posterior probabilities (BPP) ≥ 0.95 are shown above the branches. New taxa described in the present study are in bold.