Lepiota subvenenata Hai J. Li, Y.Z. Zhang & C.Y. Sun, 2019

Zhang, Yi-Zhe, Zhang, Kai-Ping, Zhang, Hong-Shun, Sun, Jian, Yin, Yu, Li, Hai-Jiao & Sun, Cheng-Ye, 2019, Lepiota subvenenata (Agaricaceae, Basidiomycota), a new poisonous species from southwestern China, Phytotaxa 400 (5), pp. 265-272 : 266-268

Lepiota subvenenata Hai J. Li, Y.Z. Zhang & C.Y. Sun , sp. nov. ( Figs. 2 , 3 )

MycoBank:—MB 829580

Diagnosis:—This species is characterized by its cream to whitish pileus covered with brownish red to violet-brown squamules, subcylindrical stipe with scattered brownish red to violet-brown squamules on the low part, and elongate, narrow ellipsoid to cylindrical basidiospores. Lepiota brunneosquamulosa differs from the new species by its brownish yellow to yellowish brown squamules on pileus, stipe which slightly inflated at base, absence of cheilocystidia, distinct longer terminal elements from pileus covering and wider basidiospores.

Holotype:— CHINA. Yunnan Province, Baoshan, Tengchong, Laifeng National Forest Park , ca alt. 1710 m, 25°1′11″ N, 98°29′77″ E, on fallen leaves of Quercus , 27 September 2017, 170927-68.

Etymology:— ‘ subvenenata ’ refers to its similarity to Lepiota venenata .

Description:— Pileus 1.6–3.5 cm diam, subglobose to campanulate when young, convex, plano-convex with obtuse umbo or applanate at maturity, cream to whitish, at the centre brownish red (9D5–8) to violet-brown (9E5–8), around the centre densely covered with concentric squamules; squamules more or less erect, minute, brown (7D8), brownish red (9D5-8) or violet-brown (9E5-8). Lamellae free, subventricose, moderately crowded, up to 3 mm wide, with lamellulae in 2–3 tiers; edge finely fimbriate under a 10x lens, concolorous with the faces. Stipe 2–3.5 × 0.2–0.4 cm, subcylindrical, more or less tapering towards the base when young, hollow; cream, reddish white (9A2), or pale red (9A3) and glabrous at the apex, pale red (8A3) to reddish white (9A2) with scattered brownish red (9D5–8) to violet-brown (10E5–8) squamules towards the base; annulus fugacious; basal mycelial pad and rhizomorphs distinct, white to cream. Odor none. Taste not recorded.

Basidiospores ( Fig. 2 ) [60/2/2] (4.9–)5–6 × 2.8–3.2(–3.5) μm, L = 5.33 μm, W = 3.01 μm, [Q = 1.56–2, av Q = 1.77 ± 0.11], elongate, narrowly ellipsoid to cylindrical, sometimes slightly curved, without a suprahilar depression, without an obvious germ pore, colourless, hyaline, smooth, slightly thick-walled, dextrinoid, weakly congophilic, not metachromatic in Cresyl Blue. Basidia 19–24 × 6–8 μm, clavate, 4-spored, rarely 2-spored. Cheilocystidia 15–22 × 4–8 μm, subcylindrical, cylindrical or narrowly clavate, with smooth, thin, hyaline walls in KOH, congophilic. Pleurocystidia absent. Squamules on pileus forming a trichoderm, composed of loose and more or less vertically arranged elements, subcylindrical to cylindrical with a narrower basal part, apically attenuate or not, sometimes with one to four secondary septa, occasionally collapsed, thick-walled (1.5–3.5 μm thick), 40–200 × 10–15 μm, with parietal, pale yellowish brown intracellular pigment. Clamp connections common in all tissues. Spore print not obtained. Habitat grows on leaf litter.

Additional specimens examined:— CHINA. Yunnan Province, Lincang, Qi Mountain , alt. 1630 m, 23°54′16″ N, 100°4′26″ E, on rotten leaves of Delonix regia , 29 August 2015, 150829-28 ; Baoshan, Tengchong, Laifeng National Forest Park , alt. 1710 m, 25°1′11″ N, 98°29′77″, on fallen leaves of Quercus , 27 September 2017, 170927-50 .

Figures

FIGURE 2. Basidiomata of Lepiota subvenenata. a. Holotype, 170927-68. b. Paratype, 170927-50. c-d. Paratype, 150829-28. (scale bars: a = 1 cm). Photos by Hai-Jiao Li.

FIGURE 3. Microscopic structures of Lepiota subvenenata (from the holotype). a. Basidiospores. b. Basidia. c. Cheilocystidia. d. Part of a squamule on pileal surface. (scale bars: a = 5 μm, b-d = 10 μm). Drawings by Hai-Jiao Li.