Caloboletus xiangtoushanensis Ming Zhang, T.H. Li & X.J. Zhong, Phytotaxa 309: 119, 2017

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 : 65

3. Caloboletus xiangtoushanensis Ming Zhang, T.H. Li & X.J. Zhong, Phytotaxa 309: 119, 2017 Figures 4 g–j, 9

Description.

Basidiomata medium-sized to large. Pileus 5.5-11 cm in diameter, convex to plane; surface dry, tomentose, yellowish brown, pale brown to brown; context 1-1.5 cm thick in the center of the pileus, yellowish, changing blue quickly when injured. Hymenophore poroid, adnate to depressed around apex of stipe; pores subround to angular, 0.5-1 mm in diameter, yellow, sometimes brownish red, changing blue quickly when injured; tubes 0.5-1.4 cm in length, yellowish, changing blue quickly when injured. Stipe 5-9 × 0.9-1.6 cm, central, subcylindric, solid, usually flexuous; surface dry, upper part covered with reddish brown, minute squamules, middle and lower part covered with brown minute squamules; context yellowish, changing blue quickly when injured; basal mycelium white. Odor indistinct.

Basidia 25-35 × 5-10 μm, clavate, thin-walled, colorless to yellowish in KOH; four-spored, sterigmata 3-4 μm in length. Basidiospores [140/8/3] (9.5 –)10–11.5(– 13) × 3.5-4.5 μm, Q=(2.11 –)2.44–3.00(– 3.29), Qm=2.76 ± 0.21, 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 colorless to yellowish in KOH, 4-10 μm wide, thin-walled hyphae. Cheilocystidia 25-45 × 7-10 μm, fusiform or subfusiform, thin-walled, colorless in KOH, no encrustations. Pleurocystidia 30-50 × 7-12 μm, fusiform or subfusiform, thin-walled, colorless in KOH, no encrustations. Pileipellis a trichoderm about 70-100 μm thick, composed of slightly interwoven, colorless or yellowish in KOH, 4-7 μm wide, thin-walled hyphae; terminal cells 35-55 × 4-7 μm, clavate or subclavate, with obtuse apex. Pileal trama made up of hyphae 3.5-7 μm in diameter, thin-walled, colorless to yellowish in KOH. Stipitipellis hymeniform about 60-80 μm thick, composed of thin- to slightly thick-walled (to 0.5 μm) emergent hyphae, colorless to yellowish in KOH, with clavate, subclavate, fusiform or subfusiform terminal cells (15-46 × 5-8 μm), and occasionally with scattered clavate, four-spored basidia. Stipe trama composed of longitudinally arranged, parallel hyphae 3.5-8 μm wide, cylindrical, thin- to slightly thick-walled (to 0.5 μm), yellowish in KOH. Clamp connections absent in all tissues.

Habitat.

Solitary or gregarious on the ground in forests dominated by fagaceous trees.

Distribution.

Southeastern and southern China.

Specimens examined.

CHINA. Fujian Province: Zhangping County, Xinqiao Town, Chengkou Village, elev. 350 m, 30 July 2013, N.K. Zeng 1330 (FHMU 883); same location and date, N.K. Zeng 1331 (FHMU 884); same location, 1 August 2013, N.K. Zeng 1354 (FHMU 906).

Notes.

Our recent collections and the holotype of C. xiangtoushanensis , a species originally described from Guangdong Province of southern China ( Zhang et al. 2017), phylogenetically group together with a strong statistical support (Fig. 2), which indicates that these specimens should be recognized as C. xiangtoushanensis . It is new to Fujian Province. Morphologically, several features of our collections also match well with the protologue of C. xiangtoushanensis ( Zhang et al. 2017), but reticulations on the stipe were not observed in our specimens. Moreover, pores of our specimens are sometimes brownish red. In appearance, C. xiangtoushanensis is highly similar to Japanese B. bannaensis Har. Takah., which needs further confirmation for generic placement ( Takahashi 2007). However, B. bannaensis has rufescent and faintly cyanescent context, small basidiospores measuring 6.5-9 × 3.5-4 μm, and narrower cystidia ( Takahashi 2007). The molecular analyses also indicates that C. xiangtoushanensis is closely related to C. taienus (W.F. Chiu) Ming Zhang and T.H. Li (Fig. 2), a species originally described from Yunnan Province ( Chiu 1948); their morphological differences have been elucidated in a previous study ( Zhang et al. 2017).