Leucocoprinus Pat.

Yang, Kun L., Lin, Jia Y., Li, Guang-Mei, Li, Taihui & Yang, Zhu L., 2024, Rediscovering Leucoagaricus sinicus, with the recognition of Leucoagaricus and Leucocoprinus as separate genera, and two new genera in Agaricaceae (Basidiomycota), Phytotaxa 676 (3), pp. 199-255 : 232-234

Leucocoprinus Pat. , Journal de Botanique (Morot) 2: 16 (1888)

Type species:— Leucocoprinus cepistipes (Sowerby) Pat. , Journal de Botanique (Morot) 3: 336 (1889) (≡ Agaricus cepistipes Sowerby, Coloured Figures of English Fungi (London) 1(1): tab. 2 (1796))

Diagnosis:— Differing from the similar genus Leucoagaricus by usually producing slender to robust basidiomata turning reddish, purplish, greenish to bluish or without a distinct color change after touched, damaged, or dried, non-plicate to plicate pileus, squamules on pileus composed of perpendicular to interwoven hyphae, basidiospores with or without a germ pore, widely distributed, saprotrophic in forests, lawns, urban areas and compost, and occasionally symbiotic with attine ant species.

General characteristics:— Basidiomata usually small to medium-sized, slender to robust, without a distinct color change or turning reddish, purplish, greenish to bluish after touched, damaged, or dried. Pileus usually convex to plano-convex, more or less umbonate, with granular, pulverulent, furfuraceous, fibrous or flaky, white or variously colored squamules on a whitish background, rarely uniformly coloured, with a non-plicate to plicate margin. Lamellae usually free, crowded, whitish, with a more or less cystidiose edge, interspersed with abundant lamellulae. Stipe usually more or less curved, subcylindrical, more or less bulbous at the base, whitish, smooth or with minute squamules. Annulus usually superior or median, almost unmoveable, with a spreading margin, easily broken. Odor usually fungal. Taste usually fungal.

Basidiospores usually more or less ovoid to amygdaliform and thick-walled, smooth, colorless to slightly colored, dextrinoid, with or without a germ pore. Basidia usually four-spored, monomorphous to polymorphous. Lamella trama usually regular, subregular to trabecular. Cheilocystidia usually present. Pleurocystidia usually absent. Pileus squamules usually composed of perpendicular to interwoven hyphae. Clamp connections absent or present.

Habits and distribution:— Usually gregarious, not or weakly caespitose, saprotrophic on soil or deadwood, or symbiotic with attine ant species in their nests, in forests, lawns, urban areas and compost, mainly known from the tropical, subtropical and temperate regions.

Notes:— In the current concept, Leucocoprinus is a moderately supported monophyletic group ( Figs. 1 & 2 ). Urrea-Valencia et al. (2023) actually generated a similar phylogeny based on ITS and nrLSU data. However, the current Leucocoprinus still looks heterogeneous in the ITS alignment ( Fig. 3 ; see also section Discussion). For example, as shwon in Fig. 3 , Lc. flammeotinctus (represented by collection DUKE-JJ97), Lc. pegleri (represented by collections JBSD130930 (holotype) and ANGE 192) and Lc. roseovertens (represented by collections JBSD130932 (holotype) and CA19) had a continuous gap region from site 215 to 328, but the other species did not have one. Nearly half of the collections had a continuous base region from site 479 to 500, but the rest showed a continuous gap region instead. The morphological differences between these groups, heterogeneous in the ITS alignment, seem indistinct.

Sequences of Lc. fragilissimus , originally described from North America, fell in three distinct clades ( Fig. 2 ). The clade comprised of Asian samples was reclassified as Lc. licmophorus , a name previously treated as a synonym of Lc. fragilissimus , originally described from Sri Lanka ( Patouillard 1913, Yang et al. 2019). It represented a newly recorded species in China ( Fig. 7 ).

New combinations:— The following new combinations are proposed based on the phylogenetic and/or morphological evidence. See below for details.

Leucocoprinus amanitoides (R.M. Davis & Vellinga) Kun L. Yang, Jia Y. Lin & Zhu L. Yang , comb. nov. Registration identifier:— FN572142

Basionym:— Leucoagaricus amanitoides R.M. Davis & Vellinga, Mycotaxon 98: 198 (2006)

Notes:— Based on the phylogenetic and morphological evidence of the following collections: R.M.Davis 03001 (from USA, sequence data available from EF080870 (ITS) & EF080872 (nrLSU), referred to Vellinga & Davis (2006)) & E.C.Vellinga 3331 (from USA, sequence data available from EF080869 (ITS) & EF080873 (nrLSU), referred to Vellinga & Davis (2006) & Vellinga et al. (2011)).

Leucocoprinus amazonicus (A. Ortiz & Franco-Mol.) Kun L. Yang, Jia Y. Lin & Zhu L. Yang , comb. nov. Registration identifier:— FN572143

Basionym:— Leucoagaricus amazonicus A. Ortiz & Franco-Mol., Mycotaxon 106: 373 (2009)

Notes:— Based on the phylogenetic and morphological evidence of the following collection: HUA (holotype, from Colombia, sequence data available from EU940371 (ITS), referred to Ortiz et al. (2009)).

Figures

FIGURE 1. Overview of the five phylogenies based on different datasets; each genus with more than one collection inferred as a monophyletic group, and the outgroup is each collapsed as a triangle; nodes are annotated if supported by ≥50% MLB or ≥0.9 BPP; holotypes and paratypes are indicated by HT, and PT, respectively. A. Main phylogeny, inferred from the concatenated ITS-nrLSU-rpb2- tef-1α dataset with 392 collections, 313 of which do not have rpb2 and tef-1α sequences; see Fig. 2 for details. B. Phylogeny S1, inferred from the concatenated ITS-nrLSU-rpb2-tef-1α dataset with 68 collections, 61 of which have three to four loci. C. Phylogeny S2, inferred from the concatenated ITS-nrLSU dataset with 392 collections. D. Phylogeny S3, inferred from the concatenated rpb2-tef-1α dataset with 48 collections, all have both rpb2 and tef-1α sequences. E. Phylogeny S4, inferred from the concatenated ITS-nrLSU-rpb2-tef-1α dataset with 134 collections representative for Agaricaceae s. l.

FIGURE 2. Details of the Main phylogeny, inferred from the concatenated ITS-nrLSU-rpb2-tef-1α dataset. 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. Each genus is highlighted with a background color. Holotypes, isotypes, paratypes, and epitypes are indicated by HT, IT, PT, and ET, respectively; note that the paratypes of a species are only indicated when its holotype is not present.

FIGURE 3. Key for the AC group genera and Micropsalliota in the ITS alignment (represented by the alignment of the Main Phylogeny (Supplementary File 3)), visualized with AliView. Note that a long continuous gap region is present in Macropsalliota and Micropsalliota (indicated by *), but is absent in Candelolepiota, Leucoagaricus, Leucocoprinus and the other genera, and this region of Micropsalliota is somewhat ahead from that of Macropsalliota.

FIGURE 7. Leucocoprinus licmophorus (photos by Kun L. Yang; drawings by Kun L. Yang, from HTBM0689). a. Squamules at the midpoint of the radius of pileus. b–c. Basidiospores (b. Line drawing; c. SEM photo of HTBM0689). d–g. Basidiomata (d–e. HTBM0578; f–g. HTBM0689). Bars: a–b = 10 µm, c = 5 µm, d = 1 cm, e–g = 2 cm.