Divergence Time Estimation

Divergence time is estimated with the BEAST v2.6.5 software package (Bouckaert et al., 2019) with 5.8S and nLSU sequences representing all main lineages in Basidiomycota (Table 2). Sequences of the species are adopted partly from the topology established by Wang et al. (2021). Neurospora crassa Shear and B.O. Dodge from Ascomycota are designated as outgroup taxon (Wang et al., 2021). A BEAST XML input file is generated with BEATUti v2. The estimation of rates of evolutionary changes at nuclear acids is using ModelTest 3.7 with the GTR substitution model (Posada and Crandall, 1998). A log-normal distribution is employed for molecular clock analysis (Drummond and Rambaut, 2007). A Yule speciation model is selected as prior assuming a constant speciation rate per lineage. Three fossil fungi, viz. Paleopyrenomycites devonicus (Taylor et al., 1999, 2005), Archaeomarasmius leggetti (Hibbett et al., 1995, 1997), and Quatsinoporites cranhamii (Smith et al., 2004; Berbee and Taylor, 2010) are taken from Wang et al.’s (2021) study. An XML file is conducted for 10 billion generations, producing log files and trees files. The log file is analyzed in Tracer 1,³ and a maximum clade credibility (MCC) tree is interpreted in TreeAnnotator by trees file, removing the first 10% of the sampled trees as burn-in, and viewed in FigTree v1.4.2.

Taxonomy

Sistotremastrum family

“Type genus”: Sistotremastrum J. Erikss.

Habitat: It grows on rotten angiosperm and gymnosperm wood.

Basidioma are resupinate, thin, pruinose, or waxy. Hymenophores are smooth, verruculose, or odontioid-semiporoid. The hyphal structure is monomitic; generative hyphae bear clamp connections, CB(+). Cystidia and hyphidia are present in some species. Basidia are clavate or cylindrical, often with a median constriction, mostly with 2–4 or 4–6 sterigmata, and rarely with 6–8 sterigmata. Basidiospores are narrowly ellipsoid, ovoid, or cylindrical, thin-walled (but the wall is distinct), smooth, inamyloid, and acyanophilous.

Notes: Sistotremastrum family accommodates the genera Sistotremastrum and Sertulicium in the order Trechisporales based on its distinct lineage in the phylogenetic analysis. The combined phylogeny of two-gene data (Figure 1) demonstrates that Sistotremastrum family forms a supported sister clade to Hydnodontaceae. Basidia of most species in the Sistotremastrum family have more than four sterigmata, and basidiospores are smooth, while basidia of species in Hydnodontaceae have four sterigmata and their basidiospores are smooth to verrucose or aculeate. In addition, ampullate septa are only present in Scytinopogon, Trechispora, and P. mucidus in Hydnodontaceae.

Trechispora dentata Z.B. Liu and Yuan Yuan, sp. November Figure 4

Open in a separate window

FIGURE 4

Trechispora dentata (holotype, Dai 22565). (A) A basidioma, (B) hyphae from subiculum, (C) hyphae from trama, (D) hyphae with ampullate septa (black arrow), (E) basidia and basidioles, and (F) basidiospores. Photo by Ya-Ping Lian and Zhan-Bo Liu.

MycoBank number: MB 842865.

Type: China, Yunnan province, Sipsongpanna, Mengla County, XiShuangBanNa Tropical Botanical Garden, on soil, in southwestern China, ca. E 101° 25′, N 21° 41′, alt. 570 m. The vegetation is a natural tropical forest. 4 July 2021, Y.C. Dai 22565 (holotype BJFC 037139).

Etymology: Dentata (Lat.): It refers to the species having a dentate hymenophore.

Basidioma: They are annual, resupinate, soft when fresh, fragile when dry, easily separable from the substratum, up to 2.5-cm long, 2-cm wide, and less than 1-mm thick at the center; hymenial surface irpicoid, white when fresh, becoming cream (4A2/3) when dry; margin indistinct and fimbriate, mycelial cords absent; pores or aculei 3–4/mm; hymenophore lacerate to dentate; subiculum very thin to almost absent; tubes or aculei concolorous with a hymenial surface, less than 1 mm long.

Hyphal structure: Hyphal system is monomitic; generative hyphae bear clamp connections; ampullate septa occasionally present in subiculum and trama, up to 5-μm wide; all hyphae IKI−, CB− are unchanged in KOH; rhomboidal calcium oxalate crystals are scattered.

Subiculum: Generative hyphae hyaline, thin- to thick-walled, frequently branched, loosely interwoven, 2–4 μm in diameter.

Tubes or aculei: Generative hyphae in trama hyaline, thin- to thick-walled, frequently branched, loosely interwoven, 2–3 μm in diameter; cystidia and cystidioles are absent; basidia are clavate or barrel-shaped, hyaline, bearing four sterigmata and a basal clamp connection, 10–15 × 4–5 μm; basidioles are similar to basidia in shape but slightly shorter.

Basidiospores: They are ellipsoid, hyaline, thick-walled, aculeate, occasionally with one guttule, IKI−, CB−, (4−)4.1–5 × (3−)3.2–4(−4.1) μm (including ornamentation), L = 4.46 μm, W = 3.66 μm, Q = 1.22 (n = 60/1); (2.2−)2.6–3.7(−3.8) × 2–2.5 μm (excluding ornamentation), L′ = 3.17 μm, W′ = 2.23 μm, and Q′ = 1.42 (n = 60/1).

Notes: T. dentata was discovered in the Yunnan Province of China. Phylogenetically, T. dentata is close to Trechispora regularis (Murrill) Liberta with strong support (96% BS, 96% BP, 1.00 BPP; Figure 2). However, T. regularis is strictly poroid (Liberta, 1973), and basidiospores of T. dentata are smaller than that of T. regularis [4.1–5 × 3.2–4 μm vs. 4–5.5 × 3.5–5 μm in T. regularis (including ornamentation); Liberta, 1973].

Trechispora dimitiella Z.B. Liu and Yuan, sp. November Figure 5

Open in a separate window

FIGURE 5

Trechispora dimitiella (holotype, Dai 21931). (A) A basidioma, (B) hyphae with ampullate septa from subiculum (black arrow), (C) hyphae from tubes, (D) basidia, (E) basidioles, and (F) basidiospores. Photo by Ya-Ping Lian and Zhan-Bo Liu.

MycoBank number: MB 842866.

Type: China, Hainan Province, Haikou, Jinniuling Park, on a rotten leaf, in southwestern China, ca. E 110° 19′, N 20° 1′, alt. 17 m. The vegetation is a plantation in tropical China. 7 November 2020, Y.C. Dai 21931 (holotype BJFC 035830).

Etymology: Dimitiella (Lat.): It refers to the species having a dimitic hyphal system.

Basidioma: They are annual, resupinate, soft when fresh, fragile when dry, easily separable from the substratum, up to 6-cm long, 4-cm wide, and approximately 3-mm thick at the center; the hymenial surface is poroid, pore surface white to cream (4A2/3) when fresh, becoming white to buff-yellow (4A4) when dry; margin indistinct, often with emerging mycelial cords; pores angular, 5–6/mm; dissepiments thin, lacerate; subiculum up to 1 mm thick; tubes concolorous with a poroid surface, up to 2 mm long.

Hyphal structure: Hyphal system is dimitic; generative hyphae bear clamp connections; ampullate septa occasionally present in subiculum and trama, up to 4.5 μm wide; all hyphae IKI−, CB− are unchanged in KOH; rhomboidal calcium oxalate crystals are scattered.

Subiculum: Generative hyphae hyaline, thin-walled, rarely branched, 2–3 μm in diameter; skeletal hyphae thick-walled with a wide lumen, unbranched, loosely interwoven, 2–4 μm diameter.

Tubes: Generative hyphae hyaline, thin-walled, rarely branched, 1.5–2.5 μm in diameter; skeletal hyphae thick-walled with a wide lumen, unbranched, loosely interwoven, 2–3 μm in diameter; cystidia and cystidioles are absent; basidia are barrel-shaped, hyaline, bearing four sterigmata and a basal clamp connection, 9.5–12 × 4–5 μm; basidioles are similar to basidia in shape but slightly shorter.

Basidiospores: They are ellipsoid, hyaline, thick-walled, aculeate, IKI−, CB−, (3.5−)3.6–4(−4.2) × (2.5–)2.7–3.1(−3.2) μm (including ornamentation), L = 3.84 μm, W = 2.92 μm, Q = 1.31–1.33 (n = 60/2); (2.6−)2.7–3.4(−3.7) × 2–2.6(−2.9) μm (excluding ornamentation), L′ = 3.04 μm, W′ = 2.18 μm, and Q′ = 1.38–1.4 (n = 60/2).

Additional specimen examined (paratypes): China, Yunnan Province, Jinghong, Primeval Forest Park, on soil, 7 July 2021, Y.C. Dai 22601 (BJFC), Dai 22602 (BJFC). Malaysia, Selangor, Kota Damansara, Community Forest Reserve, on rotten angiosperm wood, 7 December 2019, Y.C. Dai 21181 (BJFC 032835).

Notes: T. dimitiella was discovered in China and Malaysia. Most species in Trechispora are corticioid fungi with a monomitic hyphal structure, but T. dimitiella is different. Morphologically, T. dimitiella and Trechispora brasiliensis (Corner) K.H. Larss. share the poroid hymenophore with a dimitic hyphal system and aculeate basidiospores. However, the basidiospores of T. dimitiella are smaller than that of T. brasiliensis [3.6–4 × 2.7–3.1 μm vs. 4–4.5 × 3–4 μm in T. brasiliensis (including ornamentation), Larsson, 1992]. Phylogenetically, T. dimitiella is close to Trechispora incisa K.H Larss. (80% BS, 0.99 BPP; Figure 2), but T. dimitiella can be easily distinguished from T. incisa due to its poroid hymenophore with a dimitic hyphal system because T. incisa has arachnoid to farinose or minutely granulose hymenophore with a monomitic hyphal system (Larsson, 1996).

Trechispora fragilis Z.B. Liu and Yuan Yuan, sp. November Figure 6

Open in a separate window

FIGURE 6

Trechispora fragilis (holotype, Dai 20535). (A) A basidioma, (B) hyphae with ampullate septa from subiculum (black arrows), (C) hyphae from aculei, (D) hymenium with basidioles, (E) basidia, and (F) basidiospores. Photo by Ya-Ping Lian and Zhan-Bo Liu.

MycoBank number: MB 842867.

Type: China, Yunnan Province, Sipsongpanna, Mengla County, XiShuangBanNa Tropical Botanical Garden, on the ground of the forest, in southwestern China, ca. E 101° 25′, N 21° 41′, alt. 570 m. The vegetation is a natural tropical forest. 18 August 2019, Y.C. Dai 20535 (holotype BJFC 032203).

Etymology: Fragilis (Lat.): It refers to the species having fragile basidiocarps.

Basidioma: They are annual, resupinate, soft when fresh, fragile when dry, easily separable from the substratum, up to 3 cm long, 2 cm wide, and less than 1 mm thick at the center; the hymenial surface is odontoid, white when fresh, becoming cream (4A2/3) to buff-yellow (4A4) when dry; margin is indistinct and fimbriate, often with emerging mycelial cords; aculei sparse, 4–6/mm; subiculum very thin to almost absent; aculei concolorous with a hymenial surface, less than 1 mm long.

Hyphal structure: Hyphal system monomitic; generative hyphae bear clamp connections; ampullate septa occasionally present in subiculum and aculei, up to 7 μm wide; all hyphae IKI−, CB− are unchanged in KOH; rhomboidal calcium oxalate crystals are scattered.

Subiculum: Generative hyphae hyaline, thin- to thick-walled, frequently branched, loosely interwoven, 1.5–4 μm in diameter.

Aculei: Generative hyphae in trama hyaline, thin- to thick-walled, frequently branched, loosely interwoven, 1.5–3 μm in diameter; cystidia and cystidioles are absent; basidia are clavate shaped, hyaline, bearing four sterigmata, and a basal clamp connection, 12–14 × 3.5–4 μm; basidioles are similar to basidia in shape but slightly shorter.

Basidiospores: Ellipsoid, hyaline, thick-walled, aculeate, IKI−, CB−, (3.2−)3.8–4(−4.2) × (2.4−)2.5–3 μm (including ornamentation), L = 3.53 μm, W = 2.79 μm, Q = 1.27 (n = 60/1); (2.6−)2.8–3.7(−4) × (1.9−)2–2.7(−3.1) μm (excluding ornamentation), L′ = 3.16 μm, W′ = 2.26 μm, and Q′ = 1.40 (n = 60/1).

Notes: T. fragilis was discovered in the Yunnan Province of China. Phylogenetically, T. fragilis groups with Trechispora termitophila Meiras-Ottoni and Gibertoni and Trechispora havencampii (Desjardin and B.A. Perry) Meiras-Ottoni and Gibertoni (69% BS, 0.92 BPP; Figure 2). T. termitophila can be easily distinguished from T. fragilis due to its coralloid basidioma. In addition, the basidiospores of T. fragilis are smaller than that of T. termitophila [6.5–7.5 μm vs. 4.5–5 μm in T. termitophila (including ornamentation), Meiras-Ottoni et al., 2021]. T. havencampii can also be easily distinguished from T. fragilis due to its coralloid basidioma. In addition, basidiospores of T. fragilis are smaller than that of T. havencampii [3.8–4 × 2.5–3 μm vs. 5.2–6.5 × 3.5–4.2 μm in T. havencampii (including ornamentation), Desjardin and Perry, 2015].

Trechispora laevispora Z.B. Liu, Y.D. Wu and Yuan Yuan, sp. November Figure 7

Open in a separate window

FIGURE 7

Trechispora laevispora (holotype, Dai 21655). (A) A basidioma, (B,C) hyphae from subiculum, (D) subicular hyphae with ampullate septa (black arrow) and a piece of hymenium, (E) basidia and basidioles, and (F) basidiospores. Photo by Ya-Ping Lian and Zhan-Bo Liu.

MycoBank number: MB 842868.

Type: China, Inner Mongolia Autonomous Region, Arxan, Bailang Feng Scenic Spot, on the charred trunk of Larix, in southwestern China, ca. E 119° 56′, N 47° 10′, alt. 1,511 m. The vegetation is a natural boreal forest. 25 August 2020, Y.C. Dai 21655 (holotype BJFC 035556).

Etymology: Laevispora (Lat.): It refers to the species having smooth basidiospores.

Basidioma: They are annual, resupinate, soft when fresh and dry, up to 8 cm long, 3 cm wide, and less than 1 mm thick at the center; the hymenial surface is smooth, white when fresh and dry; margin is indistinct and fimbriate, often with emerging mycelial cords; subiculum very thin to almost absent.

Hyphal structure: Hyphal system monomitic; generative hyphae bear clamp connections; ampullate septa frequently present in subiculum and hymenium, up to 7 μm wide; all hyphae IKI−, CB− are unchanged in KOH; rhomboidal calcium oxalate crystals are abundant.

Subiculum: Generative hyphae hyaline, thin-walled, frequently branched, loosely interwoven, 1.5–3 μm in diameter.

Hymenium: Generative hyphae in subhymenium hyaline, thin-walled, frequently branched, 1.5–3 μm in diameter; cystidia and cystidioles are absent; basidia are clavate shaped, hyaline, bearing four sterigmata and a basal clamp connection, 11.5–15 × 4–5 μm; basidioles are similar to basidia in shape but slightly shorter.

Basidiospores: Ellipsoid, hyaline, thin-walled, smooth, IKI−, CB−, (2.5−) 2.6–3.2(−3.3) × (1.8−)1.9–2.2(−2.5) μm, L = 2.92 μm, W = 2.04 μm, and Q = 1.43 (n = 60/1).

Notes: T. laevispora was discovered in the Inner Mongolia Autonomous Region of China. Phylogenetically, T. laevispora groups with Trechispora cohaerens (Schwein.) Jülich and Stalpers with strong support (94% BS, 96% BP, 1.00 BPP; Figure 2). Both species share a smooth hymenophore, a monomitic hyphal system with smooth basidiospores. However, basidiospores of T. cohaerens are thick-walled and larger than that of T. laevispora (3.5–4 × 2.2–2.5 μm in T. cohaerens; Larsson, 1992).

B. daweishanense (C.L. Zhao) Z.B. Liu and Yuan Yuan, comb. November

MycoBank number: MB 842869.

Basionym: T. daweishanensis C.L. Zhao, Phytotaxa 479(2): 153 (2021).

Type: China. Yunnan Province, Honghe, Pingbian County, Daweishan National Nature Reserve, on the fallen branch of angiosperms, 1 August 2019, CLZhao 17860 (holotype SWFC).

Description: See Zong et al. (2021, as T. daweishanensis).

B. xanthum (C.L. Zhao) Z.B. Liu and Yuan Yuan, comb. November

MycoBank number: MB 842870.

Basionym: T. xantha C.L. Zhao, Phytotaxa 479(2): 155 (2021).

Type: China. Yunnan Province, Yuxi, Xinping County, Mopanshan National Forestry Park, on the trunk of Albizia julibrissin, 20 August 2017, CLZhao 2632 (holotype SWFC).

Description: See Zong et al. (2021, as T. xantha).

Notes: Zong et al. (2021) described T. daweishanensis and T. xantha as new species. However, in our phylogeny, they belong to the genus Brevicellicium (98% BS, 1.00 BPP; Figure 1). The type specimens of abovementioned species are studied [CLZhao 17860 (SWFC); CLZhao 2632 (SWFC)]. We do not observe ampullate hyphae from type materials as mentioned by Zong et al. (2021). We suppose that Zong et al. (2021) confused basidioles with ampullate hyphae (ampullate septa on some generative hyphae), which are remarkable characters of Trechispora. In fact, T. daweishanensis and T. xantha have a smooth hymenophore, a monomitic hyphal structure with clamped generative hyphae, and the absence of ampullate septa. They fit Brevicellicium well. Herein, we combine these two species in Brevicellicium based on morphological and phylogenetic evidence (Figure 1).

S. limonadense (G. Gruhn and P. Alvarado) Z.B. Liu and Yuan Yuan, comb. November

MycoBank number: MB 842871.

Basionym: S. limonadense G. Gruhn and P. Alvarado, Phytotaxa 498(1): 36 (2021).

Type: French Guiana. On the bark of an unidentified dead trunk lying on the ground, October 22, 2013, LIP 0001683 (holotype).

Description: See Gruhn and Alvarado (2021, as S. limonadense).

Notes: Gruhn and Alvarado (2021) described S. limonadense as a new species. However, at the same time, Spirin et al. (2021) segregated the species around S. niveocremeum (Höhn. and Litsch.) J. Erikss. into the new genus Sertulicium. In our phylogeny, S. limonadense groups with Sertulicium granuliferum (Hallenb.) Spirin and Volobuev Sertulicium lateclavigerum (Boidin and Gilles) Spirin and Viner (Figure 1). We did not study specimens, but S. limonadense is characterized by smooth to tuberculate hymenophore and basidia have 6–8 sterigmata (Gruhn and Alvarado, 2021) and fits Sertulicium better. Hence, we transfer S. limonadense to Sertulicium.