Caloboletus guanyui N.K. Zeng, H.Chai & S.Jiang

Chai, Hui, Liang, Zhi-Qun, Xue, Rou, Jiang, Shuai, Luo, Shi-Hong, Wang, Yong, Wu, Lu-Ling, Tang, Li-Ping, Chen, Yun, Hong, Deng & Zeng, Nian-Kai, 2019, New and noteworthy boletes from subtropical and tropical China, MycoKeys 46, pp. 55-96 : 62-64

2. Caloboletus guanyui N.K. Zeng, H.Chai & S.Jiang nom. nov. Figures 4 c–f, 8

Boletus quercinus Hongo, Memoirs of Shiga University 17: 92, 1967 (nom. illeg., later homonym)

non Boletus quercinus Schrad., Spicilegium Florae Germanicae 1: 157, 1794

non Boletus quercinus ( Pilát) Hlaváček, Mykologický Sborník 67(3): 87, 1990 (nom. illeg., later homonym)

Etymology.

Latin, “guanyui” is named for Guan Yu, a historic Chinese hero, said to have a reddish face, and thus sharing the same color of pores of the species when young.

Description.

Basidiomata medium-sized to large. Pileus 5-10 cm in diameter, convex to applanate; surface dry, finely tomentose, dirty white to pale brown; context 0.5-1.8 cm thick in the center of the pileus, white, changing bluish quickly when injured, then back to white. Hymenophore poroid, depressed around apex of stipe; pores subround, 0.3-0.5 mm in diameter, reddish to reddish brown when young, then yellow or yellowish brown, changing bluish black when injured; tubes about 0.5-1 cm in length, yellowish, changing bluish quickly when injured. Stipe 5.5-9 × 0.7-1.5 cm, central, subcylindric, solid, usually flexuous; surface dry, densely covered with pale brown, brown to reddish brown, minute squamules; context white, sometimes tinged with pale red, unchanging in color when injured; basal mycelium white. Odor indistinct.

Basidia 21-30 × 6-8 μm, clavate, thin-walled, colorless to yellowish in KOH; four-spored, sterigmata 3-4 μm in length. Basidiospores [220/12/5] (8.5 –)9–11(– 12) × 3.5-4.5 μm, Q=(2.00 –)2.22–2.67(– 2.86), Qm=2.43 ± 0.17, subfusoid and inequilateral in side view with a weak or distinct suprahilar depression, elliptic-fusiform to subfusiform in ventral view, slightly thick-walled (to 0.5 μm), olive-brown to yellowish brown in KOH, smooth. Hymenophoral trama boletoid; composed of yellowish in KOH, 4-10 μm wide, thin-walled hyphae. Cheilocystidia 25-40 × 7-10 μm, fusiform or subfusiform, thin-walled, colorless to yellowish in KOH, no encrustations. Pleurocystidia 35-45 × 6-11 μm, fusiform or subfusiform, thin-walled, colorless to yellowish in KOH, no encrustations. Pileipellis a trichoderm about 100-200 μm thick, composed of slightly interwoven, nearly colorless in KOH, 5-8 μm wide, thin-walled hyphae; terminal cells 28-35 × 5-10 μm, clavate or subclavate, with obtuse apex. Pileal trama made up of hyphae 4-8 μm in diameter, slightly thick-walled (to 0.5 μm), colorless to yellowish in KOH. Stipitipellis hymeniform about 80-100 μm thick, composed of thin-walled emergent hyphae, yellowish in KOH, with clavate, subclavate, fusiform or subfusiform terminal cells (27-43 × 6-11 μm), and occasionally with scattered clavate, 4-spored basidia. Stipe trama composed of longitudinally arranged, parallel hyphae 3-6 μm wide, cylindrical, thin-walled, colorless to yellowish in KOH. Clamp connections absent in all tissues.

Habitat.

Gregarious on the ground in forests dominated by Castanopsis kawakamii Hay. or Lithocarpus spp.

Distribution.

Southeastern and southern China; Japan ( Hongo 1967).

Specimens examined.

CHINA. Hainan Province: Ledong County, Yinggeling National Nature Reserve, elev. 650 m, 4 June 2017, N.K. Zeng 3058 (FHMU 2019); same location, 5 June 2017, N.K. Zeng 3079 (FHMU 2040). Fujian Province: Zhangping County, Tiantai National Forest Park, elev. 350 m, 28 August 2009, N.K. Zeng 635 (FHMU 399); Sanming City, Geshikao National Forest Park, elev. 420 m, 16 August 2017, N.K. Zeng 3257 (FHMU 2218); same location and date, N.K. Zeng 3261 (FHMU 2222); Yongan City, Tianbaoyan National Nature Reserve, elev. 600 m, 17 August 2017, N.K. Zeng 3263 (FHMU 2224).

Note.

Caloboletus guanyui was originally described as B. quercinus from Japan ( Hongo 1967). Nomenclaturally, the epithet quercinus of this species is an illegitimate name, because Schrader (1794) described a species using the same epithet before Hongo (1967). Therefore, the new epithet guanyui is proposed here for this species. Moreover, morphological and molecular evidence indicates the taxon is a member of the genus Caloboletus (Fig. 2), and is characterized by a dirty-white to pale-brown pileus, pores reddish to reddish brown when young, then yellow or yellowish brown, changing bluish black when injured, and a stipe densely covered with pale-brown, brown to reddish-brown squamules. Morphologically, C. taienus and C. xiangtoushanensis also have reddish pores ( Bessette et al. 2016; Zhang et al. 2017), however, a dirty-white to pale-brown pileus easily distinguishes C. guanyui from the two taxa. Phylogenetically C. guanyui is closely related to C. firmus (Frost) Vizzini (Fig. 2), however, C. firmus has a stipe covered with whitish or reddish reticula, and it is restricted to North and Central America ( Bessette et al. 2016).