Tylopilus jiangxiensis Kuan Zhao & Yan C. Li, 2020

Zhao, Kuan, Zhang, Fu-Mao, Zeng, Qing-Qing, Han, Li-Hong & Li, Yan-Chun, 2020, Tylopilus jiangxiensis, a new species of Tylopilus s. str. from China, Phytotaxa 434 (3), pp. 281-291 : 286-287

Tylopilus jiangxiensis Kuan Zhao & Yan C. Li , sp. nov. ( Figs. 3–4 )

MycoBank: MB 833786

Etymology: “ jiangxiensis ” refers to Jiangxi Province, China, the locality of the type specimen.

Diagnosis: —Characterized by its small basidiomata, yellowish brown pileal and stipe surface, smooth stipe, white context without color change when bruised and association with Pinaceae and Fagaceae .

Holotype: — CHINA. Jiangxi Province, Yichun city, Sanzhaolun National Forest Park, in a mixed forest dominated by Fagaceae and Pinus taiwanensis , 650 m alt., 17 June 2019, K. Zhao 1226 (HKAS 105252).

Pileus 2–3.5 cm in diameter, convex; surface yellowish brown (4C4–4C5) to reddish brown (8C6–8), much paler towards margin, margin always enrolled when immature, unchanging in color when injured. Context 0.2–0.3 cm thick, whitish, unchanging in color when injured. Hymenophore adnate to depressed around apex of stipe, surface pallid (1B1) to pinkish (11B4–6), with the pink tinge becoming darker when bruised, pores ca. 3/mm; tubes concolorous with the surface, 0.2–0.4 cm long. Stipe 5–7 × 0.4–0.7 cm, central, subcylindric, solid; surface dry, concolorous with the pileal surface but becoming lighter upward, nearly whitish at the apex, forming a sort of pseudoannular zone which abruptly delimit the color of the stipe; context concolorous with that of pileus, without color change when hurt; basal mycelium white. Taste bitter.

Basidiospores [100/4/3] 9.5–12 (13) × 3.5–4.5 μm [Q = (2.44)2.67–3.29(3.43), Q m = 2.91 ± 0.21], subfusiform to ellipsoid, slightly thick-walled (<1 μm thick), yellowish brown in KOH. Basidia 22–30 × 6–9 μm, clavate, 4- spored, colorless to yellowish in KOH; sterigmata about 5 μm in length. Hymenophoral trama boletoid, colorless to yellowish in KOH, hyphae cylindrical, 3–10 μm wide. Cheilo - and Pleurocystidia 32–50 × 7–10 μm, subfusiform to ventricose-subfusiform, thin-walled, yellowish in KOH. Pileipellis an intricate trichoderm composed of thin-walled, subcylindrical hyphae, 4–7 μm wide, yellowish to brownish in KOH; pileal trama made up of hyphae 5–12 μm in diameter, thin-walled, colorless to yellowish in KOH. Iodine reaction negative in all tissues. Clamp connections absent in all tissues.

Habitat and distribution: Solitary to gregarious in mixed forests of Pinaceae and Fagaceae . Currently only known from Jiangxi Province, southeastern China.

Additional material examined: CHINA. Jiangxi Province, Jiujiang city, Lushan Mountain, in a mixed forest of Pinus taiwanensis , Cryptomeria japonica and Fagaceae , 1050 m alt., 10 Jun 2019, K. Zhao 1221 (HKAS 105250); same place, 13 June 2019, K. Zhao 1222 (HKAS 105251); Yichun city, Sanzhaolun National Forest Park, in a mixed forest dominated by Fagaceae and Pinus taiwanensis , 650 m alt., 17 June 2019, K. Zhao 1233 (HKAS 105253).

Notes: Tylopilus jiangxiensis is characterized by its small basidiomata, yellowish brown to reddish brown pileal surface, concolorous stipe without reticulum, white context with no color change when bruised and bitter taste. In our phylogenetic analyses, it is sister to T. fellus . However, the latter species differs from T. jiangxiensis by the larger basidiomata, distinct reticulations especially on the upper part of the stipe and longer basidiospores (14–16 μm) ( Estadès & Lannoy 2004; Wu et al. 2016). Morphologically, T. jiangxiensis resembles T. vinaceipallidus , a tropical species originally described from Malaysia, as they both have brownish pileus, pinkish hymenophore and whitish context. However, the latter can be distinguished by its bigger basidiomata (pileus 4.5–12.5 cm in diameter and stipe measuring 6.5–8 × 1–2.5 cm) and the white farinose squamules on the stipe ( Wu et al. 2016). Tylopilus otsuensis Hongo (1966:60) , originally described from Japan, is also similar to T. jiangxiensis in the small basidioma and color of the hymenophore. However, T. otsuensis can be recognized by its grayish to olivaceous pileal surface and shorter basidiospores ( Hongo 1966; Wu et al. 2016).

Figures

FIGURE 3. Basidiomata of Tylopilus jiangxiensis in natural habitat. (a from HKAS 105250, b from HKAS 105251, c from HKAS 105252 and d from HKAS 105253). Bars = 1 cm.

FIGURE4.MicroscopicfeaturesofTylopilusjiangxiensis(fromHKAS 105252,holotype) a.Basidiospores.b.Basidiaandpleurocystidium. c. Cheilo- and pleurocystidia. d. Pileipellis. Drawings by Kuan Zhao.