Crepidotus herbaceus T. Bau & Y. P. Ge 2022, sp. nov.
Creators: name: Zhang, Peng
name: Ge, Yupeng
name: Bau, Tolgor
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Inocybaceae
Crepidotus
Crepidotus herbaceus

description: Crepidotus herbaceus T. Bau & Y.P. Ge sp. nov. Figs. 2, 3a, 3b, 4   
MycoBank MB837628  
Diagnosis:—Pileus minute, white, attached dorsally to stems and the underside of leaves of living plants, basidiospores oblong, finely verrucose, cheilocystidia clavate, capitate, flexuous, occasionally apically branched, pileipellis a trichoderm, terminal cells occasionally slightly capitate.  
Etymology:—The epithet refers to the habitat of the species, namely, living herbaceous plants.  
 Type:— CHINA. Jiangxi Province: Matoushan Nature Reserve, Zixi City, elev. 458 m, 27°80′ N, 117°15′ E, 11 August 2015, Tolgor Bau & Yupeng Ge, HMJAU37004 (Holotype!), GenBank nos. KX456185 (ITS), OM 010350 (nLSU).   
 Description:— Pileus 3–8 mm diam., white (1A1), in young stage angulate, reniform, rounded flabelliform to subcircular, becoming planar, flabelliform to semicircular, villose, felted-tomentose, with age slightly tomentose to almost smooth, margin slightly inflexed, not hygrophanous, without striate edge when mature, mostly attached dorsally, occasionally also attached laterally, at the point of attachment villose or fibrillose. Lamellae (1.5–)2–6(–7.2) mm long, 1–1.5 mm broad, distant, L = 5–9, l = 2–6, adnexed to adnate, ventricose to arcuate, white (1A1) when young, later grayish yellow (3B3) to brownish orange (6C5). Stipe 1.5 × 1.0 mm, white (1A1) to brownish orange (6C5), observable only when very young, white fibrillose at base. Context white, very thin. Odor and taste nondistinctive. Spore print buffy brown (5C7).   
 Basidiospores (6–)6.3–7.4(–7.8) × (3.5–)3.8–4.8(–5.1) μm, Q = (1.37–)1.40–1.70(–1.73), oblong in frontal view, slightly inequilateral to amygdaliform in side view, yellow to light rust-brown, almost smooth (under 600×) to punctate (under immersion oil), finely rugulose or rugulose-verruculose under SEM. Basidia (15–)17–20 × 6.4–8.2 μm, clavate, 2–4-spored, thin-walled, hyaline. Pleurocystidia absent. Cheilocystidia (20–)23–32(–35) × (3.9–)4.7–7.3(–8.0) μm, abundant, clustered, clavate, capitate, flexuous, occasionally branched at apex, thin-walled, hyaline. Pileipellis a trichoderm, composed of (30–)48–64(–74) × (4.1–)4.9–6.1(–6.9) μm cylindrical cells, occasionally branched, terminal cells occasionally slightly capitate, thin-walled, hyaline. Clamp connections present in all tissues.   
Habitat:—Gregarious, on the dorsal surface of leaves of herbaceous plants, occasionally on the stems.  
 Additional material examined:— CHINA. Jiangxi Province: Matoushan Nature Reserve, Zixi City, 472 m, 27°78′ N, 117°12′ E, 11 August 2015, Tolgor Bau & Yupeng Ge, HMJAU37025!. Raoqiao Town, Zixi City, 372 m, 27°83′ N, 117°14′ E, 12 August 2015, Tolgor Bau & Yupeng Ge, HMJAU37009!.   
 Notes: According to the classification proposed by Consiglio and Setti (2008), C. herbaceus should be placed in series Caspari Consiglio & Setti, section Dochmiopus Consiglio & Setti, Crepidotus subgen. Dochmiopus (Pat.) Pilát. On basis of its minute pileus and smaller basidiospores, C. herbaceus is distinguished from all five documented taxa of series Caspari (Consiglio & Setti 2008). Hesler & Smith (1965) documented four species that produce basidiospores of similar size to C. herbaceus: C. ellipsoideus Hesler & A.H. Smith (1965: 112), C. lagenicystis Hesler & A.H. Smith (1965: 113), C. phaseoliformis Hesler & A.H. Smith (1965: 92), and C. vulgaris Hesler & A.H. Smith (1965: 121). Among these four species, C. ellipsoideus and C. vulgaris possess an apparently broader pileus, and C. lagenicystis has much larger, different-shaped cheilocystidia. Crepidotus phaseoliformis has a larger pileus and possesses filamentous to cylindric cheilocystidia. In addition, the basidiospores of C. phaseoliformis are smooth, whereas those of C. herbaceus are slightly punctate (under 1000× magnification) or indistinctly smooth (under 600× magnification).   
 Crepidotus palodensis is closest to C. herbaceus in pileus size and color, but C. palodensis possess much larger basidiospores (8–10.5 × 4–5 μm) (Kumar et al. 2018). In a BLASTn search using the nLSU sequence (OM010350) of C. herbaceus as a query, the closest hit was C. versutus Peck (1886: 72) (AY820890), with 97% sequence similarity, followed by C. epibryus (MK277886), with 97% sequence similarity. Our comparison of nLSU sequences in GenBank indicates that C. herbaceus is a distinct taxon.
description: Published as part of Zhang, Peng, Ge, Yupeng & Bau, Tolgor, 2022, Two new species of Crepidotus (Crepidotaceae) from China, pp. 22-34 in Phytotaxa 552 (1) on pages 25-28, DOI: 10.11646/phytotaxa.552.1.2, http://zenodo.org/record/6673167