Xanthagaricus purpureosquamulosus Sysouph., Thongkl. & K.D. Hyde, Diversity

Yang, Kun L., Lin, Jia Y., Li, Guang-Mei, Liu, Zhen-Chao, Hosen, Md. Iqbal & Yang, Zhu L., 2024, Heinemannomyces, Hymenagaricus and Xanthagaricus revisited (Basidiomycota, Agaricaceae), Phytotaxa 659 (2), pp. 112-164 : 142-144

Xanthagaricus purpureosquamulosus Sysouph., Thongkl. & K.D. Hyde, Diversity 13(666): 34 (2021) ( Fig. 13 )

Description:— Basidiomata tiny to small. Pileus 5–12 mm in diameter, hemispherical, plano-convex to applanate, sometimes slightly depressed at center when mature; background ceramic white (#FEFEFA); squamules woolly, granular to furfurous, variable in color, dirty wisteria violet (#C5BCCC), steak purple (#877280), brick orange (#ECE2B4), dull silk red (#BBA8A2), duck blood red (#564843), muddy brown (#BD936D) or coffee-bean brown (#483625), becoming lighter towards margin; margin with appendices concolorous with the squamules on the pileus; context ceramic white (#FEFEFA) to merino white (#F9F5EC) when fresh, turning rust orange (#D79A65) after damaged. Lamellae free, nearly crowded, ceramic white (#FEFEFA), cherrywood brown (#DAB697) to muddy brown (#BD936D), with a slightly serrate edge; lamellulae abundant. Stipe 14–24 mm long, 1–1.5 mm thick, cylindrical to subcylindrical, sometimes tapering downwards, slightly curved; background ceramic white (#FEFEFA); squamules furfurous, usually more abundant below the annulus, dull dirty orange (#EBD087), mire brown (#B89F89) to duck blood red (#564843); context ceramic white (#FEFEFA) to merino white (#F9F5EC) when fresh, turning rust orange (#D79A65) after damaged; base without tomenta. Annulus superior, easily broken and fugacious, concolorous with the squamules on the stipe. Odor indistinctly fungal. Taste unknown.

Basidiospores [60/6/4] 4.5–6 [4.96 ± 0.38, 5.00] × 3–3.5 [3.08 ± 0.19, 3.00] µm, Q = (1.29) 1.43–1.83 (2.00) [1.61 ± 0.14, 1.67], ellipsoid to oblong, slightly thick-walled, smooth under LM, densely verrucose under SEM, tinged moon yellow (#FAF9AA) to lion orange (#EFD871) in both water and 5% KOH, with a small apiculus, without a germ pore. Basidia 10.5–14 × 5–7.5 μm, clavate, 4-spored, thin-walled, nearly colorless in both water and 5% KOH, with sterigmata up to 2 µm long, surrounding by basidioles measured 7–11 × 4.5–6.5 μm. Lamella trama regular to subregular, composed of 3–9 µm wide, cylindrical to subcylindrical, thin-walled, nearly colorless in both water and 5% KOH, compact, moderately to frequently branching hyphae. Cheilocystidia moderately abundant, 10–17 × 4–7 µm, variable in shape, clavate, ovoid to narrowly utriform, thin-walled, smooth, nearly colorless in both water and 5% KOH. Pleurocystidia absent. Pileus squamules epithelioid to subhymeniform, composed of globose, subglobose to clavate, slightly thick-walled and encrusted cells measured 5–15 × 4.5–12 µm, tinged wet sand yellow (#CCC796) in both water and 5% KOH. Stipe squamules structured as the same as the pileus squamules. Clamp connections absent in all tissues.

Habitat and distribution:— Gregarious, strongly caespitose, scattered on soil as clusters, in southern subtropical monsoon forests. Currently known from China (South China) and Thailand.

Collections examined:— China, Guangdong Province, Guangzhou City, Huangpu District, Jiangdong Village , Boluoshan Hill , on soil, 23°11’31”N, 113°32’48”E, elevation 150 m, June 23, 2023, Zhen-Chao Liu, Kun L. Yang & Jia Y. Lin, S 23184B ( HTBM0427 (ITS: PP736738; nrLSU: PP732968; tef-1α: PP746836 )) ; same location, August 27, 2023, Zhen-Chao Liu, Kun L. Yang & Jia Y. Lin, S23555 ( HTBM1666 (ITS: PP736648; nrLSU: PP732879 )) ; same location, August 28, 2023, Zhen-Chao Liu, Kun L. Yang & Jia Y. Lin, S23560 ( HTBM1671 (ITS: PP736649; nrLSU: PP732880 )), S23561 ( HTBM1672 (ITS: PP736650; nrLSU: PP732881 )), S23562 ( HTBM1673 (ITS: PP736651; nrLSU: PP732882 )), S23564 ( HTBM1675 (ITS: PP736656; nrLSU: PP732887; tef-1α: PP746817 ), S23564B (completely used up (ITS: PP736652; nrLSU: PP732883 )) & S23565 ( HKAS133464 , partly isolated as HTBM1676 (ITS: PP736653; nrLSU: PP732884 )) ; China, Guangdong Province, Guangzhou City, Haizhu District, Shangchong Fruit Trees Park , on soil, 23°04’36”N, 113°18’21”E, elevation 2 m, April 4, 2024, Jia Y. Lin, L 24058 ( HTBM1932 (ITS: PP736667; nrLSU: PP732897; rpb2: PP746801; tef-1α: PP746832 )), L24059 ( HTBM1933 (ITS: PP736668; nrLSU: PP732898; tef-1α: PP746833 )) & L24060 ( HTBM1934 (ITS: PP736669; nrLSU: PP732899 )) ; same location, April 7, 2024, Jia Y. Lin, L 24069 ( HKAS133467 , partly isolated as HTBM1943 )) .

Additional notes: This is the first report of this species in China. In the current phylogeny ( Fig. 2 ), our collections clustered with the holotype and paratype of X. purpureosquamulosus into a significantly supported clade with little internal variation, suggesting them to be conspecific. However, the color of pileus squamules observed in our study is dramatically variable compared to that described in the protologue ( Sysouphanthong et al. 2021). The basidiospores observed in our study are also narrower (3.08 µm wide on average), differing from the wider ones (3.78 µm wide on average) described in the protologue ( Sysouphanthong et al. 2021). If it were not for the molecular phylogenetic evidence, it seemed hard to accept them as a single species.

Figures

FIGURE 2. Phylogeny of Xanthagaricus, a part of the phylogeny of Agaricaceae s. l. inferred from the concatenated ITS-nrLSU-rpb2- tef-1α dataset in Fig. 1 (see also Supplement 3). Nodes are annotated if supported by ≥50% MLB or ≥0.9 BPP. Branches shortened to fit the page are indicated by two diagonal lines with the number of times that they are shortened. Collections sequenced in this study are highlighted in purple. Holotype collections are indicated by HT. The results of species delimitation generated from the ABGD, ASAP, and PTP programs, the accepted species delimitation, the type of basidiospore ornamentation, and the color of pileus squamules are shown on the right of the phylogenetic tree. New species proposed in this study are each annotated with a dot.

FIGURE 13. Xanthagaricus purpureosquamulosus (Photos by Zhen-Chao Liu, Jia Y. Lin & Kun L. Yang; drawings by Kun L. Yang & Jia Y. Lin, from HTBM1671, HTBM1933 & HTBM0427). a–k. Basidiomata (a–b. HTBM1671; c. HTBM1666; d. HTBM1675; e–f. HTBM1933; g–h. HKAS133467; i. HTBM1934; j–k. HTBM0427, note that those basidiomata crossed in j are X. ianthinus that grew together). l–m. Basidiospores (l. SEM photo; m. Line drawing). n. Squamules at pileus center. o. Stipe squamules. p. Hymenium and subhymenium. q. Cheilocystidia. Bars: a–d, j–k = 10 mm, e–i = 5 mm, l = 2 µm, m, p–q = 5 µm, n–o = 10 µm.