Russula hainanensis N.K. Zeng, Y.X. Han & Zhi Q. Liang, 2022

Han, Yun-Xiao, Liang, Zhi-Qun, Jiang, Shuai & Zeng, Nian-Kai, 2022, Russula hainanensis (Russulaceae, Russulales), a new species from tropical China, Phytotaxa 552 (1), pp. 35-50 : 42-45

Russula hainanensis N.K. Zeng, Y.X. Han & Zhi Q. Liang , sp. nov. ( Figs. 3–6 )

MycoBank: MB 843209

Etymology:—Latin “ hainanensis ” refers to the new species being found in Hainan Province, China.

Diagnosis:—Differs from closest species of R. sect. Ingratae by a pileus covered with large, brown to reddish brown patches; a pale yellow stipe with pale brown to brown granules; basidiospores with subreticulate ornamentation 0.3–0.6 μm high, and an association with trees of Dipterocarpaceae .

Holotype:— CHINA, Hainan Province, Wanning County, Bofangling, elev. 80 m, 29 August 2020, N. K. Zeng 4899 ( FHMU4855 ). GenBank accession numbers: 28 S = OM 280997 , ITS = OM 280999 .

Description:— Basidiomata small to medium-sized. Pileus 2.7–8 cm diam., subhemispherical at first, then broadly convex to applanate, center slightly depressed; margin slightly incurved, tuberculate-striate; surface slightly viscid, pale yellow (2A2) to brownish yellow (3A3), covered with large, brown to reddish brown (6C7) patches; context 2–6 mm thick at the center of the pileus, yellowish white, unchanging in color when injured. Hymenophore lamellate, adnate; lamellae 4–10 mm deep, subdistant, commonly forked, pale yellow (2A1) to brownish yellow (4B3), edge even, usually dark brown; lamellulae common, concolorous with lamellae. Stipe 45–76 × 9.5–15 mm, central, subcylindric to cylindric, sometimes slightly expanded towards the base, annulus absent; surface dry, pale yellow (5B3), densely covered with small, pale brown to brown granulations; context yellowish white, unchanging in color when injured. Odor not distinctive. Spore print not obtained.

Basidiospores [100/5/3] 5.5–6.5–7(–7.5) × 5–5.6–6.5 μm, Q = 1.08–1.27(–1.3), Qm = 1.16 ± 0.07, subglobose to broadly ellipsoid; ornamentation of relatively small, dense [(6–)8–10(–11) in a 3 μm diam. circle)] amyloid warts, 0.3–0.6 μm high, isolated or occasionally fused (0–3 fusions in the circle), long ridges forming an incomplete reticulum, intermixed with isolated conic to verrucous warts and short crests, connected by occasional lines [(0–) 1– 2 in the circle]; suprahilar spot inamyloid and indistinct. Basidia (36.5–)41.5–48.5–55(–59) × 6–8–9.5(–11.5) μm, hyaline in KOH, thin- to slightly thick-walled (up to 0.5 μm), clavate to subcylindric, 4-spored; sterigmata 3–6 μm, slightly tortuous, sometimes straight; basidioles cylindric, then narrowly clavate, ca. 4.5–9 μm wide. Pleurocystidia abundant, ca. 3300/mm 2, 55.5–75–90(–95) × 6–7.5–8.5(–9) μm, narrowly clavate to clavate, apex often obtuse or acute, sometimes moniliform, occasionally with 3–8 μm long appendage, slightly thick-walled (up to 0.5 μm); contents abundant granulose, yellowish in Congo Red, turning to brownish black in SV. Cheilocystida often shorter, (39.5–)47.5–56–62 × 5.5–6–7(–7.5) μm, narrowly clavate to subcylindric, apex obtuse or mucronate, sometimes with 3–6 μm long appendage, slightly thick-walled (up to 0.5 μm); contents granulose, yellowish in Congo Red, turning brownish black in SV. Lamellae edges fertile. Marginal cells (8.5–)12–16–23 × 4.5–5–6(–6.5) μm, clavate or subcylindrical, usually shorter than basidioles, slightly thick-walled (up to 0.4 μm). Lamellar trama mainly composed of sphaerocysts measuring up to 20 μm in diam, hyaline in KOH, thick-walled (up to 1.2 μm). Pileipellis orthochromatic in Cresyl Blue, not sharply delimited from the underlying context, a trichoderm 145–190 μm thick, two-layered, weakly gelatinized; composed of suprapellis (40–75 μm thick) and subpellis (63–125 μm thick). Suprapellis composed of erect to suberect hyphae 3.5–6.5 μm in diam., thin- to slightly thick-walled (up to 0.6 μm). Subpellis composed of inflated cells (5–)15– 28 μm in diam., thick-walled (up to 1.5 μm), barrel-shaped, ellipsoid or almost subglobose to globose. Acid-resistant incrustations absent. Hyphal terminations near the pileus margin composed of 1–3 unbranched cells, not flexuous, thinwalled (up to 0.4 μm); terminal cells (12.5–)15–22–28 × (4.5–)5–6–6.5 μm, mainly clavate, occasionally subcylindrical, apically obtuse; subterminal cells frequently shorter, up to 6.5 μm wide, rarely branched. Hyphal terminations on the middle part between center and margin of pileus (12.5–)14–22–33 × (3.5–)4–4.5–5.5 μm, subcylindric, apex obtuse; subterminal cells frequently shorter and occasionally inflated, up to 6 μm wide. Hyphal terminations near the pileus center less flexuous; shorter terminal cells 12–17.5–24(–31) × 3.5–4–5.5 μm, subcylindric, apex obtuse or occasionally attenuated; subterminal cells often shorter, unbranched, up to 5 μm wide. Pileal trama composed of hyphae up to 38.5 μm in diam, slightly thick-walled (up to 1 μm), hyaline in KOH. Pileocystidia near the pileus margin always one-celled, (54.5–)60–95.5–120(–155) × 5.5–6.5–7(–8) μm, cylindric to clavate, apex usually obtuse or occasionally mucronate, contents granulose, yellow in Congo Red turning to brownish black in SV. Pileocystidia near the pileus centre similar in shape and contents, (50–)59–98–138(–150) × 5–6–7(–7.5) μm, contents yellow in Congo Red, turning to brownish black in SV. Cystidioid hyphae in subpellis and context, contents granulose. Stipitipellis a cutis 45–95 μm thick, composed of thin- to slightly thick-walled (up to 0.6 μm) hyphae, 4–6.5 μm wide, yellowish brown in KOH; terminal cells 11–26.5 × 4–6.5 μm, subcylindrical or subclavate. Stipe trama mainly composed of sphaerocysts measuring up to 28 μm in diam, hyaline in KOH, thick-walled (up to 1.3 μm). Clamp connections absent in all tissues.

Habitat:—Gregarious on the ground in forests dominated by V. mangachapoi .

Known distribution:—Southern China (Hainan Province).

Additional specimens examined:— CHINA, Hainan Province, Wanning County, Bofangling , elev. 80 m, 29August 2020, N. K. Zeng 4888 ( FHMU4860 ); Baisha, Yinggeling of Hainan Tropical Rainforest National Park , elev. 650 m, 31 July 2015, N. K. Zeng 2296 ( FHMU1531 ) .

Figures

FIGURE 3. Basidiomata of Russula hainanensis. (a–b from FHMU4860; c–d from FHMU4855, holotype; e–f from FHMU1531). Photos by N.K. Zeng.

FIGURE 4. Microscopic features of Russula hainanensis (FHMU4855, holotype). a. Basidiospores. b. Basidia and basidioles.c. Marginal cells. d. Pleurocystidia. e. Cheilocystidia. Bars = 10 μm. Drawings by Y.X. Han.

FIGURE 5. Microscopic features of Russula hainanensis (FHMU4855, holotype). a. Pileipellis at pileus centre. b. Pileipellis at middle part between center and margin of pileus. c. Pileipellis at pileus margin. d. Stipitipellis. Bars = 10 μm. Drawings by Y.X. Han.

FIGURE 6. Scanning electron microscopy (SEM) photographs of basidiospores from Russula hainanensis (FHMU4855, holotype). Bars = 5 μm. Photos by X.C. Zhang.