Lepiota omninoflava Y.J. Hou & Z.W. Ge, 2020

Hou, Ya-Jun & Ge, Zai-Wei, 2020, New species of Echinoderma and Lepiota (Agaricaceae) from China, Phytotaxa 447 (4), pp. 221-236 : 226-227

Lepiota omninoflava Y.J. Hou & Z.W. Ge , sp. nov. FIG. 4a–c , 5a–c

MycoBank: MB 833777

Etymology:— omninoflava , from the Latin omnino = overall, flavus = yellow, referring to the yellow basidiomata of this species.

Diagnosis:— Lepiota omninoflava differs from related species by its yellow basidiomata and a distribution restricted to the tropics.

Type:— CHINA. Yunnan Province: Xishuangbanna, Menghai county, Mengsong township, in a tea plantation, elevation 1235 m, 100°33’ E, 22°03’ N, 1 August 2018, Y.J. Hou 15 (holotype HKAS 106734!)

GenBank Acc. No.:—ITS = MN810157, LSU = MN810092, tef 1-α = MN820923, rpb 2 = MN820951

Description:— Basidiomata ( FIG. 4a–c ) small-sized, yellow (1A8). Pileus 8–18 mm in diam., yellow (1A8), plano-convex with low, broad umbo; squamules up to 1 mm high, yellowish-brown (1B8), granular pyramidal, dense in the middle, and sparse toward the edges; margin with velar remnants, yellow (1A8), flocculent, prone to fall off. Context thin and whitish (1A1). Lamellae moderately crowded, free, yellow (1A8). Stipe 20–28 mm long, 1.5–2 mm diam., yellow (1A8), subcylindrical to cylindrical, finely pubescent at apex, with an annular zone which is more or less distinct and formed by the separation of a fluffy flocculose veil from pileus, below the annular zone covered with yellow (1A8) to tawny (5D7) fibrills, and with scattered darker granular floccose patches. Lacking a distinctive odor. Lamellar trama regular. Composed of hyphae 3–15 μm in diam. Basidia ( FIG. 5b ) 10–18 × 4–6 μm, clavate, 4-spored; sterigmata 2–3 μm long. Basidiospores ( FIG. 5a ) [40/2/2] (4.5–)5–6(–7) × 2.5–3(–3.5) μm, Q = (1.38)1.5–1.83(–2), Qm = 1.72 ± 0.13, ellipsoid to oblong, dextrinoid, colorless, thin-walled, smooth; apiculus small. Pleurocystidia absent. Cheilocystidia absent. Squamules ( FIG. 5c ) composed of chains of subglobose or ellipsoidal cells (15–30 × 14–29 μm) with yellow intracellular pigments, thick-walled. Clamp connections present in all tissues.

Habitat and Distribution:—Solitary or scattered in fertile humus; typically appearing in summer to early fall. Known from tropical southwestern China.

Additional specimen examined:— CHINA. Yunnan Province: Xishuangbanna, Mengla county, vicinity of Menglun town, elevation 720 m, 30 June 2008, Z.W. Ge 2121 (HKAS 54331!)

Comments:— Lepiota omninoflava is characterized by its yellow basidiomata. It has an umbonate pileus covered with yellow to yellowish-brown acute squamules, a pale yellow lamellae and stipe, and a stipe with yellow to tawny fibrillose-flocculose squamules. Lepiota omninoflava is similar to Echinoderma species because of structure of its squamules. Lepiota omninoflava is strongly supported in the phylogeny (100% BS, 1.0 PP) and is closely related to a clade consisting of L. echinacea , L. jacobi , L. asperula , and Lepiota aff. carinii ( FIG. 1 ). Morphologically, L. omninoflava is clearly different from these species because of its yellow basidiomata and its distribution in the humid tropics of southwestern China. Lepiota omninoflava and L. echinacea are similar in having ellipsoid to oblong basidiospores. However, L. echinacea has a thicker and longer stipe (20–95 × 3–9 mm) and a dirty white to fawn pileus that is covered with dark brown squamules ( Candusso & Lanzoni 1990). Lepiota jacobi , L. asperula and L. pseudoasperula (Knudsen) Knudsen (1980: 128) have smaller basidiospores and different pileus colors that are either grey to dark brown ( L. jacobi ), pinkish brown to olive-brown ( L. asperula ), or brown to reddish-brown ( L. pseudoasperula ) ( Atkinson 1900, Morgan 1906, Kauffman 1924, Knudsen 1978, Kuyper 1991, Malysheva 2005, Liang 2007). Lepiota carinii Bres. (1930: 598) and L. calcicola Knudsen (1980: 140) have smaller basidiospores and clavate to subcylindrical cheilocystidia and L. calcicola also has longer squamules (2–4 mm) ( Enderle & Krieglsteiner 1989, Candusso & Lanzoni 1990, Kasuya & Knudsen 2003, Gierczyk et al. 2011).

Figures

FIGURE 1. Phylogenetic tree of Echinoderma and related genera inferred from four combined loci (ITS, LSU, rpb2 and tef1-α) using Maximum Likelihood (ML). Support values are indicated above the nodes as follows: ML bootstrap value (BS) / Bayesian posterior probability (PP). Only bootstrap values over 50% and Bayesian posterior probabilities higher than 0.95 are shown. New species and a new record for China are shown in bold blue text. Clade A and Clade B are outlined in light blue boxes. Legend: C. = Cystolepiota, Me. = Melanophyllum, E. = Echinoderma, L. = Lepiota.

FIGURE 4. Lepiota omninoflava. a. Basidiomata of HKAS 54331. b, c. Basidiomata of HKAS 106734. Scale bars: a, b, c = 1 cm. Photographs by: Z.W. Ge and Y.J. Hou.

FIGURE 5. Lepiota omninoflava. a. Basidiospores. b. Basidia. c. Squamules. Scale bars: a = 5 μm, b =10 μm, c = 30 μm. a–b from HKAS 54331. c from HKAS 106734. Drawings by: Y.J. Hou.