Gerronema baishanzuense Q. Na, H. Zeng & Y.P. Ge, 2022

Na, Qin, Hu, Yaping, Zeng, Hui, Song, Zhizhong, Ding, Hui, Cheng, Xianhao & Ge, Yupeng, 2022, Updated taxonomy on Gerronema (Porotheleaceae, Agaricales) with three new taxa and one new record from China, MycoKeys 89, pp. 87-120 : 87

Gerronema baishanzuense Q. Na, H. Zeng & Y.P. Ge sp. nov.

Figs 2 , 3 , 4

Diagnosis.

Pileus dark brown at center, covered with dark brown fibrillose or pubescent. Stipe densely pruinose when young. Cheilocystidia present. Pileus trama with visible dark brown hyphae and coarse excrescences.

Holotype.

China. Zhejiang Province, Lishui City, Qingyuan County, Baishanzu, 8 Jul 2020, Qin Na, Yupeng Ge, Yaping Hu, Hui Zeng, and Zewei Liu, FFAAS0359 (collection no. MY0246).

Etymology.

Refers to the type locality.

Description.

Pileus 3.0-25.5 mm in diam., hemispherical when young, becoming applanate and slightly concave at center with age, deeply infundibuliform when old, with uplifted margin, dark brown all over when young (2F8), dark brown at center and fading to light yellowish brown (2D4) towards the margin at maturity, margin light yellowish white (2A2), translucent-striate, sulcate, surface dry, with appressed dark brown (2F8) fibrillose or pubescent, margin glabrescent and brown (2F8), fibrillose or pubescent at the center with age. Context thin and fragile, yellowish white (2A2). Lamellae subdecurrent to decurrent, ascending, cream-white (3A2) to light yellowish white (2A2), faces concolorous with the sides. Stipe slender, 4.5-26.0 × 0.5-2.0 mm, hollow, cylindrical, central, straight, light whitish yellow (4A2), base yellow-brown (4D8) when old, densely pruinose on the entire surface when young, almost glabrous when old, slightly broadened at the base. Odor and taste inconspicuous.

Basidiospores [140/7/6] (6.6) 7.5-8.4-9.3 (9.8) × (4.0) 4.4-4.9-5.4 (5.6) μm [Q = 1.65-1.74, Q = 1.72 ± 0.015] [holotype [40/2/1] (7.6) 7.9-8.6-9.5 (9.8) × (4.3) 4.5-4.9-5.5 (5.6) μm, Q = 1.72-1.74, Q = 1.74 ± 0.031], long ellipsoid, hyaline, guttulate, thin-walled, inamyloid. Basidia 31-45 × 6-9 μm, hyaline, clavate, 4-spored. Cheilocystidia 30-48 × 8-14 μm, clavate with swollen apex, or subfusiform, hyaline, thin-walled. Pleurocystidia not seen. Lamellar trama subregular; hyphae 2-10 μm wide, thin-walled, hyaline, inamyloid. Pileus trama subregular, sarcodimitic, sometimes with dark brown (4F8) hyphae. Pileipellis a cutis, hyphae 2-6 μm wide, light yellow (2B2) to yellow (2B4), occasionally with coarse excrescences; terminal elements utriform, clavate, sometimes with sparse coarse excrescences, 25-56 × 6-10 μm, light yellowish brown (2C4) to yellowish brown (2C6) pigment in KOH; true pileocystidia absent. Hyphae of the stipitipellis 2-7 μm wide, hyaline, smooth; caulocystidia cylindrical or clavate, 39-70 × 5-14 μm, hyaline, thin-walled. All tissues nonreactive in iodine. Clamps present in all tissues.

Habit and habitat.

Solitary to scattered on rotten wood, branches, and twigs in mixed forests of Picea , Pinus , Populus , Quercus , etc. Subtropical monsoon climate or subtropical humid climate.

Other specimens examined.

Anhui Province, Chizhou City, Shitai County, Dayan Village, Guniujiang National Natural Reserve, 31 Aug 2019, Qin Na, Yupeng Ge, Hui Zeng, Liangliang Qi, and Junqing Yan, FFAAS0366 (collection no. MY0260); Zhejiang Province, Lishui City, Qingyuan County, Baishanzu, 24 May 2020, Qin Na, Yupeng Ge, Yaping Hu, Hui Zeng, and Zewei Liu, FFAAS0360 (collection no. MY0247), FFAAS0362 (collection no. MY0250); Zhejiang Province, Lishui City, Qingyuan County, Jushui Village, 27 May 2020, Qin Na, Yupeng Ge, Yaping Hu, Hui Zeng, and Zewei Liu, FFAAS0361 (collection no. MY0249), Longquan City, Longquan Mountain, 11 Jul 2020, Qin Na, Yupeng Ge, Yaping Hu, Hui Zeng, and Zewei Liu, FFAAS0363 (collection no. MY0251).

Remarks.

Gerronema baishanzuense is considered to be a distinct species of Gerronema on account of its deeply infundibuliform pileus, decurrent lamellae, smooth and long ellipsoid basidiospores, sarcodimitic tramal tissues, cylindrical or clavate caulocystidia, and a lignicolous habitat ( Singer 1986; Redhead 1986; Norvell et al. 1994). Four species with a yellow pileus have been recorded: G. keralense , G. kuruvense , G. nemorale , and G. strombodes ( Singer 1970; Takashi 2009; Antonín et al. 2011; Latha et al. 2018; Takahashi 2000). Gerronema nemorale , originally described from Japan and later reported from the Republic of Korea, has the most morphological similarities to G. baishanzuense ; however, the former differs in having a smaller pileus (<20 mm in diameter) but a longer stipe (up to 40 mm), terminal elements less than 37 μm long, and much smaller caulocystidia ( Takahashi 2000; Antonín et al. 2008). In contrast to G. baishanzuense , two new species recently reported from the Indian state of Kerala, G. keralense and G. kuruvense , are easily mistaken for the new species ( Latha et al. 2018). However, the pileus of G. keralense lacks dark brown fibrillose or pubescent, has smaller and slightly thick-walled cheilocystidia, and the hyphae of its stipitipellis and caulocystidia are both thin- to thick-walled ( Latha et al. 2018). Gerronema kuruvense is always distinctly yellow, has small basidiomata (pileus <11 mm in diameter) and true pileocystidia, and lacks cheilocystidia ( Latha et al. 2018). Finally, G. strombodes , distributed in North America and Asia, differs from G. baishanzuense in having larger basidiomata, a white to grayish white pileus (up to 80 mm wide), smooth pileipellis hyphae, and the absence of hymenial cystidia ( Singer 1970; Antonín et al. 2008; Kim et al. 2014). G. citrinum (Corner) Pegler ( Pegler 1983) and G. tenue Dennis ( Dennis 1961), are allied with G. baishanzuense , but their lamellae edges without cheilocystidia. Moreover, G. citrinum has a relatively larger pileus (20-30 mm in diam.) and smaller basidiospores (6-7.5 × 3.5-4 μm), and G. tenue differs in having a citrine yellow pileus and an insititious stipe ( Dennis 1961; Pegler 1983). G. hungo (Henn.) Degreef & Eyi, reported by Degreef and Ndong (2007) as a new combination, differs in yellowish orange to brownish orange pileus, ellipsoid basidiospores, and absent cheilocystidia.

Figures

Figure 2. Fresh basidiomata of Gerronema baishanzuense Q. Na, H. Zeng & Y. P. Ge a-e FFAAS 0359 (Holotype) f-g FFAAS 0360 h-i FFAAS 0361 j-k FFAAS 0362 l-m FFAAS 0363 n-o FFAAS 0366. Scale bars: 10 mm (a-o). Photographs a-e by Qin Na; f-g by Junqing Yan h-i by Liangliang Qi j-o by Yupeng Ge.

Figure 3. Microscopic features of Gerronema baishanzuense Q. Na, H. Zeng & Y. P. Ge. (FFAAS 0359, Holotype) a-e basidiospores f basidia g-i cheilocystidia j lamellar trama k pileipellis l stipitipellis and caulocystidia. Scale bars: 5 μm (a-e); 10 μm (f-l).

Figure 4. Morphological features of Gerronema baishanzuense Q. Na, H. Zeng & Y. P. Ge. (FFAAS 0359, Holotype) a basidiomata b basidia c basidiospores d cheilocystidia e stipitipellis and caulocystidia f pileipellis. Scale bars: 10 mm (a); 10 μm (b-f). Drawing by Qin Na and Yupeng Ge.