Crepidotus stenocystis Pouzar, 2005

Materials

Type status: Other material. Occurrence: occurrenceID: 5B34AB0C-F649-5C02-B6B6-BFA9E9FD2C98; Taxon: kingdom: Fungi; phylum: Basidiomycota; class: Agaricomycetes; order: Agaricales; family: Crepidotaceae; genus: Crepidotus; taxonRank: species; Location: country: China; stateProvince: Inner Mongolia Autonomous Region; county: Chifeng City; verbatimLocality: Hexigten Banner, Bayan Aobao National Nature Reserve; Identification: identifiedBy: TieZhi Liu; Event: year: 2007; month: August; day: 21; Record Level: institutionID: CFSZ; collectionID: CFSZ 3210

Description

Pileus 10–30 (90) mm, attached laterally, semicircular when young, White (LIII) to * Cream Colour (XVI 19 ' f), when mature flabelliform to petaloid, nearly applanate, Old Gold (XVI 19 ' i) to Buffy Citrine (XVI 19 ' k), at times Saccardo's Olive (XVI 19 ' m) by basidiospores depositing on surface, margin incurved in all stages; surface pubescent when young, silky when mature, dry, not hygrophanous, non-striated; dense pubescence near the point of attachment. Lamellae 15–25 mm, L = 19–27, l = 3–7, adnexed to subdecurrent, subventricose, edge smooth, * Cream Colour (XVI 19 ' f), edge * Wood Brown (XL 17 ''') to Buffy Brown (XL 17 ''' i). Stipe as a lateral knob, White (LIII). Context White (LIII), thicker near the base, fragile in texture. Odour and taste not distinctive. (Fig. 4)

Basidiospores [110 / 3 / 1] (5.5) 5.8–6.2 – 6.7 (7.2) × (5.2) 5.3–5.8 – 6.4 (6.9) μm, Q = (1.01) 1.02–1.13 (1.15), Q m = 1.08 ± 0.03, globose to nearly globose in lateral view, yellowish-brown in 5 % KOH aqueous solution, verrucose (ornamentation type IV, Giovanni (2008)), usually containing an oil drop (under oil). Basidia 20–27 × 6.8–9.5 μm, clavate, 4 – spored, rarely 2 – spored, sterigmata 2.4–5.7 μm long, thin-walled (<0.5 μm thick), hyaline. Pleurocystidia absent. Cheilocystidia 40–66 × 7.3–10.2 μm, narrowly utriform to lageniform, elongated, sometimes near capitate, occasionally bifurcate, thin-walled (<0.5 μm thick), hyaline. Pileipellis a trichoderm, composed of nearly parallel arranged cylindrical hyphae, 6–11 μm diam., thin-walled; the terminal or middle cells sometimes differentiate into slender cylindrical hyphae, 3–6 μm diam., colourless to yellowish, oblique to erect, forming pubescence in pileus surface. Lamellae trama irregular, composed of interwoven hyphae, 10–21 μm diam. Clamp connections present in all tissues (Figs 5, 6).

Distribution

China, Czechia, Slovakia, Finland, Switzerland, Germany, United States.

Ecology

Solitary or scattered on decaying wood or dead branches of Picea meyeri.

Notes

According to the classification of Consiglio and Setti, C. stenocystis is classified as C. subg. Dochmiopus sect. Sphaeruli, based on its subglobose, verrucose basidiospores and the presence of clamp connections (Consiglio and Setti 2008). Within this section, C. stenocystis closely resembles C. applanatus (Pers.) P. Kumm., but C. applanatus differs by possessing translucent pileus, white lamellae edge and a cutis pileipellis (Senn-Irlet 1995). Initial studies of C. stenocystis were based on European specimens, with the species first described by Zdeněk Pouzar in 2005 from specimens collected in the Czech Republic (now Czechia) (Pouzar 2005). Subsequently, Consiglio and Setti considered C. stenocystis to be a synonym of C. malachius var. trichifer (C. malachius Sacc.) (Consiglio and Setti 2008). However, based on combined phylogenetic and morphological analyses, Jančovičová et al. treated C. stenocystis as a distinct and valid taxonomic different from C. malachius; we also agree with their view (Jančovičová et al. 2017). A notable macroscopic difference has been observed between European and Chinese specimens. According to the original descriptions of the European specimens, Jančovičová et al. considered the pileus of C. stenocystis to be hygrophanous (Jančovičová et al. 2017). In contrast, our examination of Chinese specimens indicate a non-hygrophanous pileus. Despite this discrepancy, we regard our specimens as C. stenocystis, attributing the observed difference to environmental factors. Previous studies have noted C. stenocystis prefers humid climates, whereas our specimens were collected from the Inner Mongolia Autonomous Region, a region characterised by a comparatively arid climate, which may cause the non-hygrophanous pileus (Pouzar 2005, Jančovičová et al. 2017). In the phylogenetic tree, our sequence clustered with European specimens in a well-supported clade. Additionally, Jančovičová et al. described C. stenocystis possessing pileocystidia to be terminal cells that have not yet differentiated into slender cylindrical hyphae. Our specimen is similar to those studied by Jančovičová et al. in other macroscopical and microscopical characteristics, especially basidiospore and cheilocystidia.