Buchwaldoboletus xylophilus (Petch) Both & B. Ortiz, Bull. Buffalo Soc., 2011

Xie, Hui-Jing, Zhang, Chun-Xia, He, Ming-Xia, Liang, Zhi-Qun, Deng, Xiao-Hua & Zeng, Nian- Kai, 2021, Buchwaldoboletus xylophilus and Phlebopus portentosus, two non-ectomycorrhizal boletes from tropical China, Phytotaxa 520 (2), pp. 137-154 : 144-146

Buchwaldoboletus xylophilus (Petch) Both & B. Ortiz, Bull. Buffalo Soc. nat. Sci. 40: 3, 2011 ( Figs. 3 , 5 )

Description:— Basidiomata medium to large. Pileus 5–10 cm diam, subhemispherical or convex, then applanate; margin decurved; surface dry, subtomentose, then squamulose, yellowish brown (4B6) to brown (6D7); context 1.7–2.4 cm thick in the center of the pileus, yellow-white (1A5) to yellow (1A6), turning blue in color when injured. Hymenophore poroid, slightly decurrent to slightly depressed around apex of stipe; pores almost round to round, 0.3–0.5 mm diam, yellow (1A7) to brownish yellow (2B8), turning blue when bruised; tubes 3–8 mm in length, light yellow (1A6), turning blue in color when injured. Stipe 8–9.5 × 1.4–2 cm, central, subcylindric; surface dry, longitudinally striate, densely covered with brown (6C7) to reddish brown (6D7) dots; context yellow (2A8) to brownish yellow (3A8), sometimes slightly bluing, sometimes intensely bluing, but not bluing at all at the base when injured; annulus absent; basal mycelium golden yellow (1A7). Odor indistinct.

Basidia 11–20 × 5–8 μm, clavate, thin-walled, 4-spored, colorless in KOH, yellow in Melzer’s reagent; sterigmata 4–5 μm long. Basidiospores [60/3/3] (4–)4.5–6(–8) × 3–4.5 μm, Q = 1.1–1.7(–2.3), Qm = 1.38 ± 0.23, ovoid to short ellipsoid, slightly thick-walled (up to 0.5 μm), yellowish brown in KOH, yellowish brown in Melzer’s reagent, smooth. Hymenophoral trama composed of thin- to slightly thick-walled (up to 0.5 μm) hyphae, 3–9 μm wide, colorless in KOH, yellow to brownish yellow in Melzer’s reagent. Cheilocystidia 11–33 × 5–9 μm, subfusiform or fusiform, thinwalled, colorless to light yellow in KOH, yellow to brownish yellow in Melzer’s reagent. Pleurocystidia 14–29 × 4–8 μm, subfusiform or fusiform, thin-walled, colorless to light yellow in KOH, yellow to brownish yellow in Melzer’s reagent. Pileipellis a trichoderm 220–300 μm in thickness, composed of hyphae thin- to slightly thick-walled (up to 0.5 μm), light yellow in KOH, yellow to brownish yellow in Melzer’s reagent, 2–8 μm in width; terminal cell 13–72 × 3–6 μm, clavate, subcylindrical or subfusiform, with obtuse apex. Pileal trama made up of hyphae 3–8 μm diam, slightly thick-walled (up to 0.5 μm), colorless to light yellow in KOH, yellow in Melzer’s reagent. Stipitipellis a trichodermlike structure 70–120 μm in thickness, composed of thin- to slightly thick-walled (up to 0.5 μm), 3–6 μm wide, light yellow in KOH, yellow to brownish yellow in Melzer’s reagent, emergent hyphae with subfusiform or clavate terminal cells (12–31 × 3–5 μm). Stipe trama composed of cylindrical, colorless to light yellow in KOH, yellow, brownish yellow, reddish brown in Melzer’s reagent, slightly thick-walled (up to 1 μm), parallel hyphae 3–13 μm wide. Clamp connections absent in all tissues.

Habitat:—Caespitose on sawdust or on ground under Bambusa remotiflora Kuntze.

Known distribution:—Southwestern and southern China, Sri Lanka, Malaysia, the Philippines ( Ortiz-Santana & Both 2011).

Specimens examined:— CHINA. Hainan Province: Yinggeling of Hainan Tropical Rainforest National Park , elev. 80 m, 25 Jul 2020, X. H . Deng 1, 2 ( FHMU5848 , 5849 ). Yunnan Province: Xishuangbanna , elev. 565 m, 26 Oct 2020, RZS-2001, RZS-2001-1, RZS-2002, RZS-2002-1, RZS-2003, RZS-2003-1, RZS-2004, RZS-2004-1 ( FHMU5930 , 5930- 1 , 5931 , 5931-1 , 5932 , 5932 - 1,5933 , 5933-1 ) .

Notes:—Our collections identified as B. xylophilus are well characterized by a large fruitbody with a yellowish brown to brown pileus, a brown to reddish brown stipe with a yellow basal mycelium, a yellowish context turning blue when injured, small basidiospores, a pileipellis composed of interwoven, filamentous hyphae, and occurrence on sawdust or on ground under B. remotiflora . However, the structure of the surface of the pileus with a subgelatinous layer beneath the thick villous layer as described by Corner (1972) was not observed in the Chinese materials. Moreover, the habitat of B. xylophilus was described as “around decaying stumps and on rotten logs” in the protologue of B. xylophilus ( Petch 1922; Pegler 1986).

Morphologically, B. xylophilus is very like B. brachyspermus ( Pegler 1983: 582) Both & B. Ortiz (2011: 5) , B. duckeanus ( Singer 1983: 95) Both & B. Ortiz (2011: 5) , B. kivuensis (Heinem. & Gooss.-Font 1955: 169) Both & B. Ortiz (2011: 4), and B. pontevedrensis Blanco-Dios (2013: 946) ( Ortiz-Santana & Both 2011; Blanco-Dios 2013). However, B. brachyspermus , originally described from Central America, has very small pores turning blackish brown when injured, a pale brown context, a russet-colored stipe, and larger cystidia (40–55 × 11–14 μm) ( Ortiz-Santana & Both 2011); B. duckeanus , firstly described from Brazil, has a smaller basidioma, a narrower trichoderm, and different cheilocystidia ( Singer et al. 1983; Ortiz-Santana & Both 2011); the African B. kivuensis has longer basidiospores (5.3–6.8 × 3.3–4.7 μm), and larger pleurocystidia (50–70 × 8–14 μm) ( Corner 1972; Ortiz-Santana & Both 2011); the European B. pontevedrensis has a robust, sulfur yellow stipe [8–10 × (2.2–) 4.2–7.1 cm], the surface of the stipe changes blue when bruised, longer basidiospores [(6.5–)7.5–10(–11.2) × (2.8–)3.5–4.5 (–5) μm], and wider hyphae (3–12.5 μm) in the pileipellis ( Blanco-Dios 2013). Buchwaldoboletus xylophilus is found geographically close to the Indian B. parvulus (Natarajan & Purush 1988: 144) Both & B. Ortiz (2011: 9) ( Ortiz-Santana & Both 2011). However, B. parvulus has a reddish yellow pileus, a very short stipe (5 × 4 mm), shorter basidiospores (5–6 × 3–4 μm), and longer cystidia (17–52 × 5–8 μm) ( Ortiz-Santana & Both 2011). The yellowish brown to brown pileus of B. xylophilus is also reminiscent of B. lignicola (Kallenb 1929: 57) Pilát (1969: 217) . However, B. lignicola , originally described from Europe, has longer basidiospores [6–9(–12) × 3–4 μm], and longer cystidia (29–80 × 4–9 μm) ( Pilát 1969; Ortiz- Santana & Both 2011).

Figures

FIGURE 3. Habitat, basidiomata and mycelia of Buchwaldoboletus xylophilus.(a, c–g, i, j from FHMU5848); b, h–i, k from FHMU5930, FHMU5930-1, FHMU5931, FHMU5933-1, FHMU5932, FHMU5932-1, FHMU5933, FHMU5933-1). b, h, i, k photos by X.H. Deng; a, c–g, j, l photos by T.W. Yang.

FIGURE 5. Microscopic features of Buchwaldoboletus xylophilus (FHMU5848). a. Basidia. b. Basidiospores. c. Cheilocystidia. d. Pleurocystidia. e. Pileipellis. f. Stipitipellis. Bars = 10 μm. Drawings by H.J. Xie.