Catathelasma laorentou 2020

Catathelasma laorentou Z.W. Ge, sp. nov.2020

MycoBank No: 830871

Holotype China. Yunnan Province: Chuxiong, Zixi Mountain, alt. 1950 m, in forest dominated by K. evelyniana Mast. and P. yunnanensis Franchet, 26 August 2017, Z. W. Ge 4070 (Holotype: HKAS 105984). GenBank accession numbers: 

– ITS, MK909107.

Morphological description 

Pileus 10–24 cm broad, hemispherical to convex at first, expanding to convex to broadly convex with age; surface initially white, then yellowish-white (1A2) to pale yellow (1A3), greyish-yellow (2B3) with age, smooth at first, irregularly depressed, margin more or less incurved, slightly viscid to viscid when wet, occasionally with whitish veil remnants. Lamellae decurrent, white to off-white when young, whitish when mature, thick, 7–15 mm in height, with 1–2 series of lamellulae, edge smooth. Stipe 6–24 × 1.5–8 cm, fusiform, attenuate downwards, straight or curved, firm, with double annulus in which the lower annulus is flimsy and the upper annulus is membranous to leathery, yellowish-white, often split into several pedals. Context white, 2.1–4.5 cm thick in pileus, white in pileus and stipe, not changing colour when cut; smell and taste farinaceous. Spore print white.

Basidiospores [70/3/3] (8) 9–12(15) × (4) 5–6.5 (7) μm (mean 9.9 ± 1.3 × 5.8 ± 0.5 μm), Q = (1.23) 1.33–2.2 (2.75), Qav = 1.72 ± 0.30, ellipsoid, oblong to subcylindrical in frontal view, subcylindrical to somewhat inequateral in side view, hyaline in KOH, amyloid, congophilous, smooth, thin walled, without germ pore. Basidia 38–50 

× 8–10 μm, narrowly clavate, 4-spored, hyaline; sterigmata up to 6 μm long. Cheilocyst-

Habitat: 

Distribution: Known from Sichuan and Yunnan provinces in south-western China.

GenBank Accession: ITSMK909107 LSUN\A  TEF1N\A

Notes:  Catathelasma laorentou is morphologically similar to C. ventricosum (Peck) Singer, a species originally described from North America. Both species have ellipsoid basidiospores, large-sized hemispherical pilei and a pileipellis composed of an ixocutis layer. However, C. laorentou has abundant clamp connections, smaller basidiospores (9–11 × 5–6 μm), larger basidia (38–50 × 8–10 μm) and is found in coniferous forest dominated by P. yunnanensis and K. evelyniana from south-western China, while C. ventricosum is found alongside hardwood (Singer 1940)

Reference: Zai-Wei Ge1,2, Jian-Yun Wu1,2, Yan-Jia Hao3 , et al.

Figure 2  Basidiomes of Catathelasma species in China. A Catathelasma laorentou (HKAS 92245)