Most species of Candolleomyces have brown or dark brown spores. Although pale-spored members are rare in the genus we frequently collected two such species from many Provinces during our investigations in subtropical China from 2016–2020. As revealed by morphological characterisation and multigene phylogenetic analyses (ITS LSU β-tub and tef-1α) these species which we have named C. subcacao and C. subminutisporus are unique and distinct from known taxa. In addition a new combination C. cladii-marisci is proposed on the basis of ITS sequence analysis of the type specimen. Detailed descriptions colour photos illustrations and a key to related species are presented.

Basidiomycete, new taxon, Psathyrellaceae, phylogenetic analysis, taxonomy

On the basis of extensive comparisons of gene sequences and phylogenetic analyses, the historical genus Psathyrella (Fr.) Quél. has been split into several genera. One of these genera is Candolleomyces D. Wächt. & A. Melzer, which differs from Psathyrella s.s. in lacking pleurocystidia (Örstadius et al. 2015; Wächter and Melzer 2020). Approximately 100 taxa (including synonyms and subspecies) without pleurocystidia have been previously described in Psathyrella s.l. (Fries 1838; Smith 1972; Kits van Waveren 1985; Örstadius and Kundsen 2012; Battistin et al. 2014); however, many of these taxa have been treated as synonyms, as unique features, based on conventional methods, are scarce (Galland et al. 1979; Kits van Waveren 1980; Knudsen and Vesterholt 2012). Currently, 26 species have been assigned to Candolleomyces (Wächter & Melzer, 2020).

According to the research of Wächter and Melzer (2020), Candolleomyces may be more speciose than previously thought and better delimitation of species boundaries is needed. Although controversies still exist regarding some species boundaries, the number of new taxa is steadily increasing (Melzer et al. 2018; Sicoli et al. 2019a; Büttner et al. 2020). This continuous discovery of new taxa with clear boundaries deepens understanding of the species in this genus.

Approximately eight taxa in the genus Candolleomyces have previously been reported from China (Yan 2018). During our investigations in subtropical China from 2016–2020, we frequently collected two unknown Candolleomyces species with pale spores from many Provinces. Spores that are pale or almost colourless in water and 5% potassium hydroxide (KOH) are very rare in this genus. On the basis of our morphological and phylogenetic analyses, the specimens are described as new species in this paper.

According to a BLAST analysis, the ITS sequence of C. subcacao is 98% similar (eight different loci) to that of C. cacao (Desjardin & B.A. Perry) D. Wächt. & A. Melzer and approximately 97% similar (19 different loci) to five ITS sequences from two unnamed species (KP686450 for BAB-4773, KR349656 for BAB-5172, KR154977 for BAB-4748, KR154976 for BAB-4747 and KT188611 for BAB-5202) isolated from Oeceoclades maculata (Lindley) Lindley (Bayman et al. 2016). The ITS sequence of C. subminutisporus shares 97% similarity (22 different loci) with that of C. sulcatotuberculosus (J. Favre) D. Wächt. & A. Melzer. The generated BI and ML trees are shown in Fig. 1 and Suppl. material 1, respectively. In both trees, sequences of the two new species comprise strongly supported clades that are distinct from closely-related taxa. The C. subcacao clade groups together with C. cacao and two unnamed species with high statistical support, while the C. subminutisporus clade clusters with C. singeri (A.H. Sm.) D. Wächt. & A. Melzer and C. sulcatotuberculosus. The type sequence of Psathyrella cladii-marisci Sicoli, N.G. Passal., De Giuseppe, Palermo & Pellegrino is clearly nested within Candolleomyces, where it groups most closely, although with only weak to moderate support, with C. badhyzensis (Kalamees) D. Wächt. & A. Melzer, C. badiophyllus (Romagn.) D. Wächt. & A. Melzer and C. candolleanus (Fr.) D. Wächt. & A. Melzer.

Figure 1. 

Phylogenetic tree of Candolleomyces. The tree was generated by Bayesian analysis of a concatenated dataset of sequences from four nuclear regions (ITS, LSU, tef-1α and β-tub). Psathyrella multipedata (Peck) A.H. Sm. was used as an outgroup. Bayesian posterior probabilities (BI-PP) ³ 0.95 and Maximum Likelihood bootstrap support values (ML) ≥ 75% are shown above nodes as BI-PP/ML. ● indicates newly-described species.

Taxonomy

Candolleomyces subcacao T. Bau & J.Q. Yan, sp. nov.

MycoBank No: 839231

Fig. 2

Holotype

China. Henan Province: Bird Island, Nanwan Lake, Xinyang City, 32°06'43.32"N, 113°06'03.06"E, 124 m elevation, 17 July 2016, Tolgor Bau, Jun-Qing Yan, HMJAU37807 (holotype!)

Etymology

Referring to its morphological similarity to C. cacao.

Diagnosis

Differs from C. cacao in having a distinct spore germ pore.

Description

Pileus 11–35 mm, spreading hemispherically to planar, hygrophanous, brown (7E7–7E8), striate up to halfway from the margin or indistinct, becoming slightly dirty white (7B1–7B2) upon drying. Veil pale brown (7A5–7B6), thin, fibrillose, falling off easily. Context thin and very fragile, dirty white (7B1–7B2), approximately 1.0 mm thick at the centre. Lamellae 3.0–4.0 mm wide, moderately close, adnate to slightly adnexed, pale brown (C3–C4) to dark brown (7D6–7E6), saw-toothed under 20× magnification. Stipe 40–50 mm long, approximately 2.0 mm thick, white (7A1–7B1), hollow, equal, smooth, with white fibrils (7A1–7B1) at the base. Odour and taste indistinct.

Spores 6.8–8.0(8.8) × 3.9–4.9 μm, Q = 1.4–1.8, ellipsoid to oblong-ellipsoid, profile slightly flattened on one side, rarely phaseoliform, inamyloid, smooth, pale yellow-brown, darkening in 5% KOH, pale brown, germ pores distinct, but small, approximately 1.0 μm wide. Basidia 17–22 × 6.1–7.3 μm, clavate, hyaline, 4-spored. Pleurocystidia absent. Cheilocystidia 22–36 × 9.8–14 μm, scattered to moderately numerous, various, utriform to fusiform, with an obtuse to broadly obtuse apex, rarely subcapitate or clavate, ovoid, thin-walled. Trama of gills irregular. Pileipellis consisting of 2–3 cells in the deep layer of the subglobose cell, 20–37 μm wide.

Habit and habitat

Solitary to scattered on rotten wood in oak forest.

Other specimens examined

China. Henan Province: Bird Island, Nanwan Lake, Xinyang City, 17 July 2016, Tolgor Bau and Jun-Qing Yan, HMJAU37808, HMJAU37809; Borden Forest Park, Xinyang City, 17 July 2017, Jun-Qing Yan, HMJAU37898, HMJAU37899, HMJAU37900, HMJAU37948, HMJAU44554; Jiangxi Province: Jiangxi Agricultural University, Nanchang City, 3 June 2019, Jun-Qing Yan, HFJAU0716, 9 June 2019, Jun-Qing Yan, HFJAU1274; Yun Bi Feng National Forest Park, Shangrao City, 5 July 2019, HFJAU1014.

Figure 2. 

Basidiomata and microscopic features of Candolleomyces subcacao a–c Basidiomata d spores e basidia f pileipellis g cheilocystidia. Scale bars: 10 mm (a–c); 10 μm (d–g).

Candolleomyces subminutisporus T. Bau & J.Q. Yan, sp. nov.

MycoBank No: 839232

Fig. 3

Etymology

Referring to the small spores.

Holotype

China. Henan Province: Boerdeng National Forest Park, Xinyang City, 16 July 2017, Tolgor Bau and Jun-Qing Yan, HMJAU37801 (holotype!).

Diagnosis

Differs from C. sulcatotuberculosus in having smaller spores (5.8–6.8 μm long).

Description

Pileus 8.0–22 mm, spreading hemispherically to broadly conical convex, hygrophanous, pale yellow-brown (6C7–6C8) at the centre, pale at the margin (6A2–6A4), striate from margin to centre, becoming pale brown (6B6–6B7) when dry. Veil present in early stages, thin, white (6A1), fibrillose, evanescent. Context thin and very fragile, 1.0–1.5 mm thick at the centre, same colour as the pileus. Lamellae 2.5–3.0 mm wide, adnate, moderately close, white (6B1) to pale coffee (6B2–6B3), edges saw-toothed under 20× magnification. Stipes 15–40 mm long, 1.0–2.0 mm thick, cylindrical, hollow, white (6B1), sometimes subhyaline or slightly yellow-brown (6A2–6B2) at the base, apex pruinose, evanescent, slightly expanded at the base. Odour and taste indistinct.

Spores 5.8–6.8(7.8) × 3.8–4.9 μm, Q = 1.4–1.8, ovoid, ellipsoid to oblong-ellipsoid, in profile flattened on one side, rarely phaseoliform, inamyloid, smooth, very pale, nearly hyaline in water and 5% KOH, germ pore absent. Basidia 14–20 × 7.3–7.8 μm, 4-spored, clavate, hyaline. Pleurocystidia absent. Cheilocystidia 20–32 × 11–17 μm, utriform, with obtuse apex, bottom side tapering to the long or short stipe. Caulocystidia 27–42 × 6.1–9.8 μm, present at the apex, mostly solitary, various, similar to cheilocystidia or clavate and subcapitate or not. Trama of gills irregular. Pileipellis consists of 1–2 cells in a deep layer of the subglobose cell, up to 36 μm broad.

Figure 3. 

Basidiomata and microscopic features of Candolleomyces subminutisporus a–c Basidiomata d spores e basidia f pileipellis g cheilocystidia h caulocystidia. Scale bars: 10 mm (a–c); 10 μm (d–h).

Habit and habitat

Scattered on rotten wood or humus in Pinus massoniana and oak forests.

Other specimens examined

China. Anhui Province: Huangshan City, 3 July 2018, Jun-Qing Yan, HFJAU1253, HFJAU1361; Guangxi Zhuang Autonomous Region: Qingxiushan National Forest Park, Nanning City, 12 Aug 2016, HMJAU37930; Phoenix Valley Forest Park, Nanning City, 17 Aug 2016, Jun-Qing Yan, HMJAU37950; Henan Province: Boerdeng National Forest Park, Xinyang City, 16 July 2017, Jun-Qing Yan, HMJAU37916, HMJAU37958; 17 July 2017, Jun-Qing Yan, HMJAU37959, HMJAU37960, HMJAU37961: Hubei Province: Dagui Temple National Forest Park, Suizhou City, 16 July 2016, Tolgor Bau and Jun-Qing Yan, HMJAU37800; Jiangxi Province: Lushan Mountain, Jiujiang City, 30 June 2020, Jun-Qing Yan, HFJAU0921; Yunnan Province: Kunming Botanical Garden, Kunming City, 6 Aug 2016, Jun-Qing Yan, HMJAU37929.

New combination

Candolleomyces cladii-marisci (G. Sicoli, N.G. Passalacqua, A.B. De Giuseppe, A.M. Palermo & G. Pellegrino) J.Q. Yan, comb. nov.

MycoBank No: 839233

Psathyrella cladii-marisci Sicoli, N.G. Passal., De Giuseppe, Palermo & Pellegrino, MycoKeys 52: 99, 2019. Basionym.

Note

According to the ITS phylogenetic analysis including the type specimen, P. cladii-marisci belongs to Candolleomyces and has a close phylogenetic relationship with C. candolleanus, C. badiophyllus and C. trinitatensis. In addition, the morphological characteristics of this species correspond to Candolleomyces, which lack pleurocystidia.

For detailed descriptions and line drawings of this species, see Sicoli et al. (2019a; b).

Most species of Candolleomyces have dark brown or brown spores, whereas species with pale spores are rare. Candolleomyces subcacao is very easily confused with C. cacao in the field because of their similar macroscopic characteristics. In addition, these two species have highly similar ITS regions (98%). Nevertheless, some members of Candolleomyces with high ITS similarity are still treated as separate species on the basis of morphological characters (Sicoli et al. 2019a; Büttner et al. 2020; Wächter and Melzer 2020). Candolleomyces subcacao and C. cacao group together, but comprise independent lineages, in the phylogenetic tree (Fig. 1). Moreover, C. cacao has ventricose to broad lageniform cheilocystidia, an indistinct germ pore in 5% KOH and a tropical distribution (Desjardin 2016).

On the basis of morphology, C. subcacao has been classified into Psathyrella sect. Spintrigerae using the classification system of Kits van Waveren (1985; 1987) and Psathyrella sect. Subatratae, based on the system of Smith (1972). Some species in these sections lack pleurocystidia and may thus actually belong to Candolleomyces, but molecular analyses of type materials are needed prior to their possible reassignment. In this paper, we have, therefore, only compared these species and the new ones with respect to morphology (see the key below). In particular, two species in these sections possess the combined characteristics of small basidiomata, a pale brown and evanescent veil and pale yellow-brown spores with a distinct germ pore: P. lacuum Huijsman, which can be distinguished from C. subcacao by the presence of a veil with dispersed white arachnoid fibrils or flocci, abundant pyriform cells at the marginal of the lamellae and very rare utriform cheilocystidia (Kits van Waveren 1985; Battistin et al. 2014) and P. cordobaensis A.H. Sm., which differs mainly in having a 10 mm wide pileus, an indistinct germ pore and saccate to ellipsoid cheilocystidia (Smith 1972; Desjardin 2016).

Candolleomyces subminutisporus is characterised by the presence of small basidiomata, a pileus that is striate from the margin up to the centre and very pale to nearly hyaline spores that are mainly less than 7.0 μm long. Candolleomyces sulcatotuberculosus and C. subminutisporus are morphologically very similar and are phylogenetically closely related (Fig. 1); however, the former has a sulcate-tuberculose pileus surface and much larger spores, which measure (7.6)7.9–8.5(9) × (4.5)4.6–5.0(5.2) μm (Einhellinger 1976). Although Kits van Waveren (1985) and Battistini (2014) detected some smaller spores in these species, which measured (6.2)6.9–7.8(8.9) × (3.6)4.1–4.7(5.0) μm, most spores of C. sulcatotuberculosus are clearly longer than 7.0 μm.

Candolleomyces singeri (A.H. Sm.) D. Wächt. & A. Melzer, C. eurysporus A. Karich, E. Büttner & R. Ullrich and C. aberdarensis (A. Melzer, Kimani & R. Ullrich) D. Wächt. & A. Melzer group together with C. subminutisporus in the phylogenetic tree (Fig. 1). These species can be separated as follows: C. singeri has larger spores, mostly 6.8–7.8 μm long (Smith 1972, pers. obs. of HMJUA37867 by JQ Yan), whereas C. eurysporus can be separated on the basis of its broader spores, a Q-value of 1.2–1.6(–1.7) and brown lamellae at maturity (Büttner et al. 2020) and C. aberdarensis is distinguished by having larger spores [7.5–8(–8.8) μm long] (Melzer et al. 2018). In addition, two species are morphologically similar to C. subminutisporus in having more-or-less pale spores, germ pores that are indistinct or lacking and no pleurocystidia. These species can be separated from C. subminutisporus as follows: C. halophilus (Esteve-Rav. & Enderle) D. Wächt. & A. Melzer has larger spores, which are 8.6–11 × 4.8–6.2 μm (Esteve-Raventós and Enderle 1992; Battistin et al. 2014) and C. subsingeri (T. Bau & J.Q. Yan) D. Wächt. & A. Melzer is easily distinguished on the basis of its stout basidiomata (Yan and Bau 2018a).

Finally, P. cladii-marisci was described by Sicoli et. al. (2019) and is characterised by the absence of pleurocystidia and the presence of large spores up to 11 μm long (Sicoli et al. 2019a; b). According to our phylogenetic analysis, this species is relatively closely related to C. candolleanus, C. badiophyllus and C. trinitatensis and should be moved to Candolleomyces. A new combination is thus proposed.

This work is supported by the National Natural Science Foundation of China (No. 31960008 and 32070010); and Jiangxi Provincial Natural Science Foundation (20202BABL213041). We thank Dr. Barbara Goodson for editing the English text of this manuscript.