Crocinoboletus laetissimus (Hongo) N.K. Zeng, Zhu L. Yang & G. Wu

Zeng, Nian-Kai, Wu, Gang, Li, Yan-Chun, Liang, Zhi-Qun & Yang, Zhu L., 2014, Crocinoboletus, a new genus of Boletaceae (Boletales) with unusual boletocrocin polyene pigments, Phytotaxa 175 (3), pp. 133-140 : 135

Crocinoboletus laetissimus (Hongo) N.K. Zeng, Zhu L. Yang & G. Wu , comb. nov.

Figs. 1 , 3

MycoBank: MB 809230

Boletus laetissimus Hongo, Memoirs of the Faculty of Liberal Arts and Education, Shiga University 18: 49, Fig. 20/1–3, 1968

Pileus 3.8–7 cm in diameter, subhemispherical when young, then convex to applanate; surface dry, golden yellow, bright orange to reddish orange, covered with minute, dark reddish brown squamules, turning bluish olivaceous quickly, then blackening when bruised; margin decurved; context vivid golden yellow, turning bluish olivaceous quickly when bruised. Hymenophore poroid, adnate or slightly depressed around apex of stipe; pores subcircular, minute, about 0.7 mm in diameter, orange, turning bluish olivaceous quickly, then blackening when bruised; tubes 3–4 mm in depth, golden yellow to orange, turning bluish olivaceous quickly, then blackening when bruised. Stipe 6–11 × 1.2–2 cm, centrally attached, subcylindric, solid; surface dry, concolorous with the pileus, sometimes covered with dark reddish orange squamules, turning bluish olivaceous quickly, then blackening when bruised; context vivid golden yellow, turning bluish olivaceous quickly when bruised; annulus absent. Basal mycelium orangish yellow. Odor not distinct. Taste not distinct.

Basidia 24–35 × 7–10 μm, clavate, thin-walled, 4-spored; colorless to yellowish in KOH; sterigmata 5–6 μm in length. Basidiospores [56/2/2](9–)9.2–12(–14) × 4–5 μm, Q = (1.84–)1.98–2.60 (–3.00), Q m = 2.23 ± 0.22, subfusiform to ellipsoid, slightly thick-walled (up to 0.5 μm), olive brown to yellowish brown in KOH, smooth, inamyloid. Hymenophoral trama subboletoid with weakly gelatinous lateral strata. Cheilocystidia 19–28 × 3.5–5 μm, subfusiform or fusiform, thin-walled, colorless, brownish yellow to yellowish brown in KOH, no encrustations. Pleurocystidia 28–44 × 4–8 μm, fusiform or subfusiform, thin-walled, colorless, brownish yellow to yellowish brown in KOH, no encrustations. Pileipellis an interwoven trichoderm at the middle part of the pileus and a cutis at the margin of the pileus; composed of thin-walled hyphae 3–6 μm wide, occasionally branched, with terminal cells 18–80 × 2.5–4 μm, narrowly clavate or subcylindrical, with obtuse apex; yellowish to yellowish brown in KOH. Pileal trama made up of hyphae 3–6 μm in diameter, thin-walled, colorless to yellowish in KOH. Stipitipellis a trichoderm-like structure composed of thin- to slightly thick-walled (up to 0.5 μm) hyphae 3–12.5 wide, with narrowly or broadly clavate, subfusiform terminal cells measuring 13–30 × (3–)5–12.5 μm, yellowish to yellowish brown in KOH, and occasionally with clavate, 4-spored basidia at the apex of the stipe. Stipe trama composed of cylindrical parallel hyphae 4–12 μm wide, thin- to slightly thick-walled (up to 1 μm), colorless to yellowish in KOH. Clamp connections absent in all tissues.

Habitat and habitat: Solitary on the ground in mixed forests of Fagaceae and Pinaceae .

Known distribution: Japan ( Hongo 1968, 1984), subtropical and tropical regions of China.

Materials examined: CHINA. Yunnan Province: Dai Autonomous Prefecture of Xishuangbanna , 9 July 2006, Y. C . Li 478 ( HKAS 50232 ); Nanhua County, bought from agriculture supermarket, 2 August 2009, Y. C . Li 1953 ( HKAS 59701 ) .

Figures

FIGURE 1. Basidiomata of Crocinoboletus species. a–g. Crocinoboletus rufoaureus [a from HKAS 82334; b, e from HKAS 82333; c, e from HKAS 59821; d, f, g from HKAS 82335 (f showing the surface of the pileus turning bluish olivaceous, then blackening when bruised; g showing the surface of the stipe turning bluish olivaceous, then blackening when bruised)]. h, i. Crocinoboletus laetissimus (h from HKAS 50232; i from HKAS 59701) (a–g photo N.K. Zeng; h, i photo Y.C. Li).

FIGURE 3. Microscopic features of Crocinoboletus laetissimus (a–c, f, g from HKAS 59701; d, e from HKAS 50232. drawn by G. Wu). a. Basidia and a pleurocystidium. b. Basidia. c. Basidiospores. d. Cheilocysitidia. e. Pleurocysitidia. f. Pileipellis (from the middle part of the pileus). g. Pileipellis (from the marginal part of the pileus). Bars = 10 μm.