Agaricus thiersii Kerrigan & Vellinga

Cho, Minseo, Kwon, Sun Lul, Jang, Seokyoon, Yoo, Yeonjae, Lee, Sang Hyun, Kwon, Dae Young, Kim, Changmu, Lim, Young Woon & Kim, Jae-Jin, 2024, Notes of 15 unrecorded macrofungi in Korea, Journal of Species Research 13 (1), pp. 67-88 : 70-72

Agaricus thiersii Kerrigan & Vellinga ,

Memoirs of the New York Botanical Garden 114: 340 (2016) [MB#802557] ( Figs. 1A and 2A ) Korean name: ứǧȃșḡfflŷ

Pileus convex, margin slightly incurved, 34 mm in diam.

Pileus surface dark vinaceous to reddish brown, formed of radially oriented hyphae, forming large blunt appressed concentric zones distal to the disc, background whitish. Lamellae free, close. Veils are not observed in young state. Stipe equal, 35 × 6 mm, surface glabrous, white. Hyphal system monomitic, generative hyphae simple septate, rarely branched, without clamp connections, thin-walled, hyaline, 2.7-4.9 μm. Basidia clavate, 4-spored, smooth, thin-walled, hyaline, without a clamp connection, 17.1-26.7 × 4.5-7.9 μm. Cheilocystidia obovoid to pyriform, smooth, thin-walled, hyaline, 9.6-12.7 × 6.1- 7.6 μm. Basidiospores cylindrical, smooth, thick-walled, yellowish to pale brown, 4.9-6.2 × 2.9-3.5 μm [Q = 1.69- 1.78].

Specimen examined. Korea, Gangwon-do , Hwacheongun, Mt. Gwangdeok, 38°06 ʹ 59.68 ʺ N, 127°25 ʹ 58.83 ʺ E, 1,023 m, mixed hardwood forest, occurring solitary on the ground covered with litters and substrates, 07 Sep 2018, S. Jang and S. L. Kwon, KUC20180907-19 (NIBRFG 0000514540) .

Notes - Agaricus L. is a genus that includes more than

500 species worldwide ( Zhao et al., 2011; Kerrigan, 2016; Chen et al., 2017), and it is classified into six subgenera and 26 sections ( Zhao et al., 2016; Chen et al., 2017; Callac and Chen, 2018; He et al., 2018; Parra et al., 2018; Bashir et al., 2021; Ortiz-Santana et al., 2021). Currently, 12 species are accepted as Agaricus subgenus Spissicaules sect. Subrutilescentes ( Edwards et al., 2004; Kerrigan et al., 2005; Zhao et al., 2011; Lebel and Syme, 2012; Dai et al., 2016; Kerrigan, 2016; Zhao et al., 2016; Ortiz-Santana et al., 2021), and only one species ( A. subrutilescens ) is reported in Korea. Agaricus thiersii is characterized by dark vinaceous to reddish brown pileus with large blunt-appressed concentric zones, obovoid to pyriform cystidia, and yellowish to pale brown basidiospores ( Kerrigan, 2016). KUC20180907-19 has similar morphological characteristics to the original description, but our specimen has a smaller pileus compared to the original description (55- 300 mm) and veils are not observed ( Kerrigan, 2016). This might be due to the young stage of our specimen. Phylogenetically, A. thiersii is classified as Agaricus subgenus Spissicaules sect. Subrutilescentes ( Kerrigan, 2016) . Agaricus parasubrutilescens is the sister species ( Fig. 3 ), but it differs from A. thiersii by a brown-colored pileus and larger cystidia (15-28× 10-19 μm) ( Zhao et al., 2016). Agaricus thiersii was previously reported in Canada and USA ( Kerrigan, 2016), so this is the first report of A. thiersii in Asia.

Figures

Fig. 1. Macro-morphological characteristics of fifteen unrecorded macrofungi in Korea. A. Agaricus thiersii; B. Baorangia alexandri; C. Boletellus putuoensis; D. Entoloma bulakhae; E. Entoloma pygmaeopapillatum; F. Entoloma subtenuicystidiatum; G. Gerronema kuruvense; H. Hyphoderma nudicephalum; I. Hyphoderma tenue; J. Macrolepiota subcitrophylla; K. Mycena jingyinga; L. Mycena yuezhuoi; M. Ophiocordyceps vespulae; N. Scytinostroma acystidiatum; O. Steccherinum straminellum (scale bar=10 mm for A-D, G-J, M-O; 5 mm for E, F, L; and 2.5 mm for K).

Fig. 2. Micro-morphological characteristics of fifteen unrecorded macrofungi in Korea. A. Agaricus thiersii; B. Baorangia alexandri; C. Boletellus putuoensis; D. Entoloma bulakhae; E. Entoloma pygmaeopapillatum; F. Entoloma subtenuicystidiatum; G. Gerronema kuruvense; H. Hyphoderma nudicephalum; I. Hyphoderma tenue; J. Macrolepiota subcitrophylla; K. Mycena jingyinga; L. Mycena yuezhuoi; M. Ophiocordyceps vespulae; N. Scytinostroma acystidiatum; O. Steccherinum straminellum(scale bars=10μm).

Fig. 3. The phylogenetic tree of Agaricus thiersii (KUC20180907- 19). The tree was constructed based on ITS gene datasets of the genus Agaricus subgenus Spissicaules. Agaricus bellanniae was used as an outgroup. The newly generated sequence is shown in blue and bold. Bootstrap support values more than 70 are shown.