Introduction

By a recent molecular investigation based on several independent genetic loci, seven genera were identified within the family Inocybaceae Jülich: Auritella Matheny & Bougher, Inocybe (Fr.) Fr., Inosperma (Kühner) Matheny & Esteve-Rav., Mallocybe (Kuyper) Matheny, Vizzini & Esteve-Rav., Nothocybe Matheny & K.P.D. Latha, Pseudosperma Matheny & Esteve-Rav., and Tubariomyces Esteve-Rav. & Matheny (Matheny et al. 2020). The newly established genus Pseudosperma was earlier classified as Inocybe section Rimosae sensu stricto (= Pseudosperma clade) (Matheny 2005; Larsson et al. 2009) in the subgenus Inosperma (Kuyper 1986; Bon 1997).

Species of Pseudosperma are characterized by a rimose pileus, a furfuraceous stipe, smooth, elliptic to phaseoliform basidiospores, hyaline non-necropigmented basidia, cylindric to clavate cheilocystidia with thin walls, and absence of pleurocystidia (Bandini and Oertel 2020; Cervini et al. 2020; Matheny et al. 2020; Saba et al. 2020). Pseudosperma species form ectomycorrhizal symbioses with species of angiosperms and rarely gymnosperms and occur in a variety of habitats, including temperate forests (Kuyper 1986; Stangl 1989; Jacobsson 2008).

Currently 80 species of Pseudosperma are known worldwide (Bandini et al. 2022, 2023), including species recently described from Austria (Bandini et al. 2021), Australia (Matheny and Bougher 2017), China (Yu et al. 2020; Mao et al. 2022; Yan et al. 2022; Zhao et al. 2022), Germany (Bandini and Oertel 2020; Bandini et al. 2021, 2022, 2023), India (Latha et al. 2023), Italy (Cervini et al. 2020; Sanna et al. 2024), Pakistan (Jabeen and Khalid 2020; Saba et al. 2020; Jabeen et al. 2021; Naseer et al. 2023), Spain (Sanna et al. 2024), Sweden (Bandini et al. 2023), Turkey (Kaygusuz et al. 2023) and USA (Kropp et al. 2013; Matheny and Kudzma 2019). Despite this progress, the diversity of Pseudosperma species, particularly in tropical regions such as West Africa and Mediterranean areas of Western Eurasia, is poorly studied. In addition to this, there are numerous cryptic and semi-cryptic species waiting for discovery (Ryberg et al. 2008; Matheny and Bougher 2017; Yan et al. 2022).

West Africa is a region of species rich ecosystems with forests ranging among the 25 world hotspots that deserve top conservation priorities (Myers et al. 2000). The mycological exploration of West Africa, however, shows that the identified fungal species diversity in six countries in this region does not exceed 2% of the existing diversity of fungi (Piepenbring et al. 2020). For Benin, only 432 fungal species have been listed by Piepenbring et al. (2020). To date, there are two species of Pseudosperma reported from Benin, namely Pseudosperma squamatum (J.E. Lange) Matheny & Esteve-Rav., formerly known as Inocybe squamata J.E. Lange (Lange 1917; Boa 2004; Piepenbring et al. 2020), and Pseudosperma rimosum (Bull.) Matheny & Esteve-Rav. previously called Inocybe fastigiata var. brevispora R. Heim (Heim 1931; Matheny et al. 2020), which was described from Madagascar. No further species of Pseudosperma has ever been cited for any African country according to the literature available to us.

This study aims to increase the knowledge of the species diversity of Pseudosperma, with particular emphasis on the description of four new species from Benin and one from Turkey. Thereby, we contribute to the knowledge of morphological diversity, ecology, biogeography, and phylogeny of these hidden fungal treasures of Western Eurasia and West Africa.

Materials and methods

Sampling and morphological studies

The specimens from Benin were collected during a mycological survey conducted from June to August 2022. In Turkey, samples were picked up during fieldwork in the Isparta Province in 2022 and 2023. The macroscopic characteristics were obtained from fresh specimens, field notes and photographs taken in situ. Standardized colour values were documented using the Munsell Soil Color Charts (Munsell 1975). Microscopic features were observed using 1% Congo red (w/v) or 5% potassium hydroxide (KOH) (w/v). All samples were analysed and photographed with a light microscope. A minimum of thirty basidiospores were measured for each collection. Q values (ratio of length to width of basidiospore) and average values (length and width of basidiospore or cystidia) are presented. SD is the abbreviation for the standard deviation of the length × width. The terminology of Vellinga (1988) is used for macro- and micro-characters. Index Fungorum (http://www.IndexFungorum.org) and the International Index of Plant Names (https://www.ipni.org) were used as sources for taxonomic names and nomenclature. The samples from Benin are deposited in the fungarium of the Staatliches Museum für Naturkunde Stuttgart (STU) or the mycological herbarium of the University of Parakou (UNIPAR). The Turkish specimens are stored in the fungarium of the Isparta University of Applied Sciences (ISUF).

Molecular analyses

Genomic DNA was isolated from Pseudosperma specimens using the innuPREP Plant DNA Kit (Analytik Jena, Jena, Germany) and the Fungi/Yeast Genomic DNA Isolation Kit (Norgen Biotek Corp, Ontario, Canada). For amplification of nuclear rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) the primer pair ITS1F/ITS4 (White et al. 1990; Gardes and Bruns 1993), for the nuclear 28S rDNA (LSU) the primer pair LR0R/LR5 (Vilgalys and Hester 1990; Rehner and Samuels 1994), and for RPB2 the primer pair RPB2-5F/RPB2-7cR (Song et al. 2016) were used. Polymerase chain reaction (PCR) procedures were performed according to the methods described by Matheny (2005) and Kaygusuz et al. (2020). The PCR products were sequenced at Microsynth Seqlab (Göttingen, Germany) and the Sanger DNA sequencing service of Source Bioscience (Berlin, Germany), using the same primers. The obtained DNA sequences were aligned and analysed using ClustalX (Thompson et al. 1997) and MEGA X v.10.0.5 (Kumar et al. 2018) and subsequently submitted to GenBank.

A total of 27 DNA sequences (nine from the ITS, nine from the LSU, and nine from the RPB2) from nine collections were newly generated. BLASTn searches were conducted in the NCBI GenBank. For phylogenetic analyses, sequences with high similarity (with maximum identities larger than 82%) to the new sequences were retrieved from GenBank (www.ncbi.nlm.nih.gov) and UNITE (https://unite.ut.ee/, Kõljalg et al. 2005) databases, along with the sequences listed in Table 1. The ITS, LSU, and RPB2 sequences were separately aligned using MAFFT 7.11 (Katoh et al. 2019) applying the E-INS-i iterative method, followed by manual corrections in AliView V.1.28 (Larsson 2014). Mallocybe agardhii (N. Lund) Matheny & Esteve-Rav. (AB980912) and M. picea L. Fan & N. Mao (BJTC FM555) were designated as outgroups. Multiple sequence alignments were inspected using MEGA X 10.0.5 prior to subsequent analyses. A single combined dataset of ITS-LSU-RPB2 sequences was assembled for phylogenetic analysis. The optimal evolutionary model for each segment was determined using MrModeltest 2.3 (Nylander 2004). Phylogenetic assessments employed both Maximum Likelihood (ML) and Bayesian Inference (BI) approaches on the concatenated gene regions. The ML analysis was conducted with RAxML 8.2.9. (Stamatakis 2014), using the ML + rapid bootstrap setting and the GTRGAMMAI substitution model with one thousand bootstrap iterations. The BI analysis using the Markov Chain Monte Carlo (MCMC) method was conducted in MrBayes 3.2.5 (Ronquist et al. 2012) over 1 900 000 generations, sampling trees every thousand generations. The mean standard deviation of the split frequencies < 0.01 was an indication of convergence. Phylogenetic trees were visualized using FigTree v1.4.4 (Rambaut 2018), with only Maximum Likelihood Bootstrap (MLB) values above 75% and Bayesian Posterior Probabilities (BPP) exceeding 0.90 being indicated.

Table 1 List of taxa included in the molecular analyses, with voucher specimen numbers, country of origin, GenBank accession numbers of ITS, LSU, and RPB2 gene sequences, and references to literature. Information on newly generated sequences is written in bold
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Results

Phylogeny

The combined ITS, LSU, and RPB2 sequence dataset for Pseudosperma species, including 27 new sequences of the specimens from Benin and Turkey, consisted of 107 taxa with 3574 characters, of which 850 were parsimony-informative, 594 parsimony-uninformative, and 2130 constant sites. The best model, GTR + I + G, was used for all the loci (ITS, LSU, and RPB2). This matrix exhibited 1725 unique alignment patterns. The estimated nucleotide substitution rates were as follows: A-C = 1.033265, A-G = 3.791763, A-T = 1.430448, C-G = 0.427887, C-T = 5.497537, G-T = 1.00000. Base frequencies were determined as A = 0.266, C = 0.191, G = 0.256, T = 0.287. The gamma distribution shape parameter α was calculated to be 0.282. Phylogenetic trees derived from ML and BI analyses showed largely congruent topologies. The topology resulting from the ML analysis was selected for presentation, with statistical support values indicated by Maximum Likelihood Bootstrap (MLB) and Bayesian Posterior Probabilities (BPP) values (Fig. 1).

Fig. 1
figure 1

Phylogenetic position of the Beninese and Turkish collections of Pseudosperma based on the combined ITS, LSU, and RPB2 gene sequences using Maximum Likelihood (ML) and Bayesian analyses. MLB ≥ 75% and BPP ≥ 0.90 values are indicated on the branches. Mallocybe agardhii (AB980912) and M. picea (BJTC FM555) were selected as outgroups. The newly generated sequences are marked in red bold. The araneosum subclade formed by species from the palaeotropics and Australia is marked by a grey background

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Molecular analyses based on the combined dataset revealed that Pseudosperma specimens from Benin and Turkey are genetically distinct from other species within the genus represented by molecular sequences data. Their sequences form part of five independent lineages, as shown in Fig. 1. The first lineage with high statistical support (MLB = 100%, BPP = 1.0) consists of three specimens of the new species called Pseudosperma tiliae together with P. mediterraneum (Kuyper) Bandini, B. Oertel & U. Eberh. from Italy in the same subclade. The second lineage (MLB = 99%, BPP = 1.0) consists of Pseudosperma stramineum and five undescribed and unpublished sequences (HLA0707, HLA0386, 486ad3d1, 79c39691 and ASV_39) from Benin. The third lineage is formed by a single sequence labelled as Pseudosperma squarrosofulvum (AR-22–024) from Benin. The fourth lineage (MLB = 100%, BPP = 1.0) includes the new species Pseudosperma beninense (AR-22–037) from Benin and an undescribed and unpublished sequence from an uncultured fungus (ASV_330). Pseudosperma beninense, P. squarrosofulvum, and P. stramineum form a distinct, statistically highly supported clade of exclusively Beninese species (MLB = 100%, BPP = 1.0). The last lineage (MLB = 100%, BPP = 1.0) comprises the new species Pseudosperma cremeo-ochraceum (AR-22–088) and three undescribed and unpublished sequences (HLA0454, ASV_313, 881fdb9c) from Benin. The new sequences from Benin are located in a clade formed by a total of ten known species that all originate from the palaeotropics (and subtropics). The sequences of the recently collected Pseudosperma specimens consistently form distinct lineages in all phylogenetic analyses and can not be assigned to any existing Pseudosperma species concept by morphological characteristics. Therefore, we propose them as species new to science and provide detailed descriptions of these species in the following.

Taxonomy

Pseudosperma beninense Kaygusuz, Bandini, Rühl, Sarawi, Yorou & M. Piepenbr., sp. nov. (Figs. 2 and 3).

Fig. 2
figure 2

Basidiomata of Pseudosperma beninense (AR-22–037, holotype). Bar = 5 mm

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Fig. 3
figure 3

Microscopic features of Pseudosperma beninense (AR-22–037, holotype). a Basidiospores. b Basidia. c Paracystidia. d Cheilocystidia. e Pileipellis. f Caulocystidia. Bars = 10 μm

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MycoBank: MB 851970.

Etymology: The specific epithet refers to the country where the type specimen was collected.

Holotype: Benin, Borgou Department, Fôret Classée de l'Ouémé Supérieur, on soil in savannah forest dominated by Isoberlinia doka Craib & Stapf, I. tomentosa (Harms) Craib & Stapf, Monotes kerstingii Gilg and Uapaca togoensis Pax, at 09°15′37.9″N, 002°11′03.9″E, 340 m asl., 18 June 2022, leg. A. Rühl, C. Manz, D. Dongnima, F. Hampe & S. Sarawi (AR-22–037, STU). GenBank accession numbers PP060393 (ITS), PP060408 (LSU), and PP430968 (RPB2).

Diagnosis: Most similar to P. squamatum but differs from it by smaller basidiomata with brown to straw-brown pileus, whitish to light yellow stipe, longer basidiospores (on average 12.5 × 7.0 μm) mostly with acute apex, longer (on av. 51 × 14 μm) and oblong to cylindrical or narrowly clavate cheilocystidia, and by distinct ITS, LSU, and RPB2 sequences.

Description: Pileus 7–14 mm diam., when young paraboloid, later hemispherical to convex, with or without low and broad umbo, margin inflexed when young, later long deflexed, surface dry, tomentose-lanose to subtomentose, radially fibrillose to rimulose outwards, velipellis absent, colour light brown (2.5Y 8–7/6, 8/8) to straw brown (2.5Y 6/4–6), slightly darker at the centre (2.5Y 6/8). Lamellae moderately crowded, adnexed, subventricose, whitish to yellowish-white or light yellow, edge slightly eroded, whitish. Stipe 17–25 × 1.2–1.8 mm, central, cylindrical with subbulbous base up to 2.5 mm diam., solid, cortina not observed, surface whitish to light yellow, pruinose only near the apex. Colour of exsiccate: pileus very light yellow to light straw yellow (5Y 8/2–4, 7/4), lamellae and stipe whitish. Smell unrecorded.

Basidiospores 10.7–14.7 µm (av. 12.5 µm, SD ± 0.4 µm) × 6.2–8.3 µm (av. 7.0 µm, SD ± 0.5 µm); Q = 1.4–2.1 (av. 1.8, SD ± 0.1) (n = 90 of 1 coll.), mainly (sub)amgydaliform with acute apex, also subcylindrical and subellipsoid, with guttules, smooth, thick-walled, dark yellowish brown in 5% KOH. Basidia 35–42 × 10–13 µm, clavate, 4-spored, thin-walled, hyaline. Cheilocystidia 37–65 µm (av. 51 µm, SD ± 7.0 µm) × 9–20 µm (av. 14 µm, SD ± 2.3 µm); Q = 2.4–5.8 (av. 4.2, SD ± 0.6) (n = 45 of 1 coll.), mostly oblong to cylindrical or narrowly clavate, sometimes with subcapitate apex, sometimes in chains of 1–3 cells, thin-walled, hyaline or very pale yellowish-brown in 5% KOH. Paracystidia 20–35 × 9–14 µm, cylindrical to broadly clavate, in chains of 2–4 cells, thin-walled, hyaline or very pale yellowish-brown in 5% KOH. Pileipellis cutis, consisting of long cylindrical or narrowly fusiform terminal cells, with sharply pointed apex, 60–170(220) × 11–25 µm, smooth, thin-walled, pale yellowish-brown in 5% KOH. Caulocystidia composed predominantly of multiseptate cylindrical to inflated hyphae, 10–100 × 6.5–12 µm, sometimes with subcapitate apex, often in bundles, smooth, thin-walled, hyaline in 5% KOH. Stipitipellis a cutis of parallel hyphae, 5–18 µm wide, thin-walled, hyaline in 5% KOH. Clamp connections present in all parts examined.

Habitat and distribution: Basidiomata solitary, terrestrial, on wet and sandy soils, growing in a forest dominated by species of Caesalpiniaceae (Isoberlinia spp.), Dipterocarpaceae (Monotes kerstingii), and Phyllanthaceae (Uapaca togoensis). Currently known from Benin and an environmental sequence of a soil sample from West Africa (ASV_330).

Discussion: Phylogenetic analyses inferred from the combined ITS, LSU, and RPB2 sequences show that Pseudosperma beninense forms a monophyletic subgroup within Pseudosperma and is closely related to P. squarrosofulvum and P. stramineum, two other new species presented in this study. When the ITS sequences generated from Pseudosperma beninense are compared with the sequences of P. squarrosofulvum and P. stramineum, 56 nucleotide differences (83% similarity) were observed in the ITS sequences of P. squarrosofulvum and 52 differences (85% similarity) in the sequences of P. stramineum.

Morphologically, Pseudosperma squarrosofulvum differs from P. beninense by its pileus surface, which is covered by yellow ochre to brownish-yellow fibrillose scales, longer basidiospores (on av. 12.9 × 6.2 µm), somewhat shorter and narrower cheilocystidia (on av. 44 × 11 µm), mostly utriform paracystidia, pileipellis hyphae often with encrusted walls, and mostly cylindrical or narrowly clavate caulocystidia. Pseudosperma stramineum has a predominantly straw-yellow to buff pileus with a distinct squamulose-squarrose surface, pale brown lamellae when old, mostly oblong basidiospores, smaller cheilocystidia (on av. 40 × 14 μm), a pileipellis with strongly incrusted walls, and somewhat shorter caulocystidia (up to 90 μm in length).

Morphologically, the species closest to the new species Pseudosperma beninense is P. squamatum, which differs mainly by larger basidiomata, with a pileus measuring 30–70 mm in diameter, yellowish to yellow-ochraceous pileus, often with orange tinged, a longer stipe (up to 70 mm), shorter basidiospores (on av. 9.9 × 6.1 µm), shorter cheilocystidia (on av. 44 × 14 µm) that are subclavate to subglobose, and a habitat with a clay soil as well as an associated with Populus sp. (Lange 1917; pers. observation of D. Bandini). In addition, P. beninense is distant from P. squamatum following phylogenetic analyses (Fig. 1).

Other species that are morphologically somewhat similar to Pseudosperma beninense are P. fissuratum (Matheny & Bougher) Matheny & Esteve-Rav., P. gracilissimum (Matheny & Bougher) Matheny & Esteve-Rav., P. palaeotropicum (E. Turnbull & Watling) Matheny & Esteve-Rav. and P. renisporum (E. Horak) Matheny & Esteve-Rav. Pseudosperma fissuratum, originally described from Australia, differs from P. beninense by a typically bicoloured pileus, the presence of a velipellis, shorter basidiospores (on av. 11.4 × 6.2 µm), longer cheilocystidia (up to 72 µm in length), and ecologically by an association with Eucalyptus sp. (Matheny and Bougher 2017). Another Australian species, Pseudosperma gracilissimum, has a markedly conical pileus, slightly shorter basidiospores (on av. 9.9 × 5.9 µm), and is associated with Acacia, Allocasuarina, Corymbia, Eucalyptus, Lophostemon, and Melaleuca (Matheny and Bougher 2017). Pseudosperma palaeotropicum, initially discovered from Singapore and later reported from Australia and Malaysia, has larger basidiomata with a pileus measuring 20–40 mm in diameter, a longer stipe (40–70 × 4.0–6.0 µm), considerably shorter basidiospores (7.0–8.3 × 4.8–6.5 µm), and is typically associated with species of Dipterocarpaceae (Turnbull 1995). Pseudosperma renisporum, originally described from New Zealand, has a squamulose pileus centre, bean-shaped and shorter basidiospores (9.0–12.0 × 4.5–6.5 μm), and is associated with species of Leptospermum and Nothofagus (Horak 1978).


Pseudosperma cremeo-ochraceum Kaygusuz, Bandini, Rühl, Sarawi, Yorou & M. Piepenbr., sp. nov. (Figs. 4 and 5).

Fig. 4
figure 4

Basidiomata of Pseudosperma cremeo-ochraceum. a, b Collection AR-22-088 (holotype). c, d Collection AR-22-089. Bars = 5 mm

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Fig. 5
figure 5

Microscopic features of Pseudosperma cremeo-ochraceum (AR-22-088, holotype). a Basidiospores. b Basidia. c Cheilocystidia. d Paracystidia. e Pileipellis. Bars = 10 μm

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MycoBank: MB 851972.

Etymology: The specific epithet refers to the cream to ochraceous colour of the surface of the pileus.

Holotype: Benin, Borgou Department, Fôret l'Ouémé Supérieur, on the soil in savannah forest dominated by Isoberlinia doka, I. tomentosa, Monotes kerstingii and Uapaca togoensis, at 08°36′04.7″N, 002°36′00.7″E, 340 m asl., 28 June 2022, leg. A. Rühl, C. Manz, D. Dongnima, F. Hampe & S. Sarawi (AR-22–088, STU). GenBank accession numbers PP060394 (ITS), PP060409 (LSU), and PP430969 (RPB2).

Diagnosis: Most similar to the tropical Australian species Pseudosperma gracilissimum, but differing by a silky fibrillose pileus, longer basidiospores (on av. 12.9 × 7.8 µm), mostly narrowly utriform to utriform cheilocystidia with subcapitate apex, pileipellis elements without encrusted walls, the presence of caulocystidia, a different habitat dominated by Isoberlinia spp., M. kerstingii and U. togoensis, and by distinct ITS, LSU, and RPB2 sequences.

Description: Pileus 10–15 mm diam., broadly conical to hemispherical, expanded plano-convex, usually with a low umbo, with a straight and translucently striate margin reaching up to 1/4 or 2/4 of the radius, without velipellis, colour cream (2.5Y 8–7/2) to yellowish brown (2.5Y 7/6–10) or ochraceous (2.5Y 6/6–8), becoming darker at the centre with age, always creamy white (2.5Y 8/2–4) to ivory white (2.5Y 7/2) at the edge, surface dry, radially silky-fibrillose. Lamellae moderately crowded to subdistant, adnexed, subventricose, pale ivory white to pale yellow grey, becoming yellowish white, edge somewhat eroded, whitish. Stipe 12–20 × 0.6–1.2 mm, central, cylindrical, sometimes subbulbous at the base, straight or curved towards the base of the stipe, cortina not observed, surface sordid white or cream to light brown when old, slightly pruinose only near the apex. Colour of exsiccate: pileus sordid white coloured, lamellae and stipe whitish. Smell unrecorded.

Basidiospores 11.0–16.0 µm (av. 12.9 µm, SD ± 1.2 µm) × 6.5–9.3 µm (av. 7.8 µm, SD ± 0.6 µm); Q = 1.4–1.9 (av. 1.7, SD ± 0.1) (n = 100 of 2 coll.), mostly oblong, with central germ pore, with guttules, smooth, thick-walled, yellowish brown in 5% KOH. Basidia 35–45 × 11–13 µm, clavate, 4-spored, thin-walled, hyaline. Cheilocystidia 40–80 µm (av. 51 µm, SD ± 6.0 µm) × 10–17 µm (av. 13.0 µm, SD ± 2.0 µm); Q = 3.1–5.3 (av. 4.1, SD ± 0.6) (n = 40 of 1 coll.), scattered, narrowly utriform to utriform mostly with subcapitate apex, hyaline or very pale yellowish-brown in 5% KOH. Paracystidia 25–40 × 10–18 µm, utriform with obtuse or subcapitate apex or fusiform, thin-walled, hyaline or very pale yellowish-brown in 5% KOH. Pileipellis a hymeniderm to epithelium formed by broadly fusiform to cylindrical terminal elements, with obtuse to mucronate apex, 47–95 × 20–40 µm, smooth, thin-walled, pale yellowish-brown in 5% KOH. Caulocystidia 15–35 × 10–15 µm, narrowly clavate, on clusters of erect hyphae, smooth, thin-walled, hyaline in 5% KOH. Stipitipellis a cutis of subparallel hyphae, 6–12 µm wide, thin-walled, hyaline in 5% KOH. Clamp connections present in all parts examined.

Habitat and distribution: Basidiocarps gregarious, usually terrestrial, on wet and sandy soils, in woodlands dominated by Caesalpiniaceae (Isoberlinia spp.), Dipterocarpaceae (Monotes kerstingii), and Phyllanthaceae (Uapaca togoensis). Currently known from Benin and from two environmental sequences of soil samples from West Africa (ASV_313 and 881fdb9c).

Additional specimen examined: Benin, Borgou Department, Fôret Classée de l'Ouémé Supérieur, on the soil in savannah forest dominated by Isoberlinia spp., 08°36′04.7″N, 002°36′00.7″E, 340 m asl., 28 June 2022, leg. A. Rühl, C. Manz, D. Dongnima, F. Hampe & S. Sarawi (AR-22–089, UNIPAR).

Discussion: The molecular analyses revealed that Pseudosperma cremeo-ochraceum belongs to a distinct phylogenetic branch within the araneosum subclade that is strongly supported (MLB = 100%, BPP = 1.0). This subclade comprises species that are distributed in the tropics, in Australia, South Asia, and West Africa.

Pseudosperma cremeo-ochraceum is most closely related to several tropical species, including P. araneosum (Matheny & Bougher) Matheny & Esteve-Rav., P. beninense, P. brunneosquamulosum (K.P.D. Latha & Manim.) Matheny & Esteve-Rav., P. fulvidiscum Y.G. Fan, L.N. Zhao & W.J. Yu, P. rubrobrunneum (K.P.D. Latha & Manim.) Y.G. Fan, P. singulare Y.G. Fan, L.N. Zhao & W.J. Yu, P. squarrosofulvum, and P. stramineum. Pseudosperma araneosum differs from P. cremeo-ochraceum by lamellae that are very pale brown to brown when young, shorter basidiospores (on av. 10.2 × 6.1 µm), absence of caulocystidia, mostly cylindrical cheilocystidia, and habitats in lowland tropical sclerophyll swamps (Matheny and Bougher 2017). Pseudosperma beninense differs from P. cremeo-ochraceum by a lightly brown to straw brown pileus, a tomentose-lanose to subtomentose surface of its pileus, (sub)amgydaliform basidiospores with an acute apex, mostly oblong to cylindrical or narrowly clavate cheilocystidia and longer pileipellis elements (up to 220 μm in length). Pseudosperma brunneosquamulosum and P. rubrobrunneum, originally described from tropical India, differ from P. cremeo-ochraceum by notably shorter basidiospores (on av. 9.0 × 5.9 µm and av. 8.3 × 5.5 µm, respectively), versiform cheilocystidia, and associations with Vateria indica L. and Hopea ponga (Dennst.) Mabb., respectively (Tibpromma et al. 2017). Other similar Asian species are Pseudosperma fulvidiscum and P. singulare from tropical China. These species differ from P. cremeo-ochraceum by much shorter basidiospores (on av. 9.3 × 5.6 µm and on av. 9.1 × 6.1 µm, respectively) and an association with Carpinus londoniana var. lanceolata (Zhao et al. 2022). Pseudosperma squarrosofulvum has a brown-orange pileus and oblong, clavate or fusiform cheilocystidia. Pseudosperma stramineum has a straw-yellow or buff pileus, a squamulose-squarrose or lanose surface of its pileus, and shorter basidiospores (on av. 11.3 × 6.8 µm).

Pseudosperma renisporum known from New Zealand differs from P. cremeo-ochraceum by a squamulose pileus, kidney-shaped and shorter basidiospores (9.0–12.0 × 4.5–6.5 µm), cylindrical to clavate cheilocystidia, absence of caulocystidia, and a habitat in mixed forests with Leptospermum or Nothofagus (Horak 1978).

Pseudosperma brunneoumbonatum Saba & Khalid, P. pinophilum Saba & Khalid and P. triaciculare Saba & Khalid from Pakistan superficially resemble P. cremeo-ochraceum. However, Pseudosperma brunneoumbonatum differs by a strongly brown pileus, phaseoliform or ellipsoid basidiospores, clavate cheilocystidia, and an ecological association with Pinus sp. (Saba et al. 2020). Pseudosperma pinophilum differs by a pale to light yellow stipe, clavate or cylindrical cheilocystidia, and absence of caulocystidia (Saba et al. 2020). Pseudosperma triaciculare differs by a brownish-orange to fulvous pileus, the presence of a velipellis, shorter basidiospores (on av. 10.2 × 6.9 µm), cylindrical to clavate cheilocystidia, and a habitat with Pinus sp. (Saba et al. 2020).


Pseudosperma squarrosofulvum Kaygusuz, Bandini, Rühl, Sarawi, Yorou & M. Piepenbr., sp. nov. (Figs. 6 and 7).

Fig. 6
figure 6

Basidiomata of Pseudosperma squarrosofulvum (AR-22–024, holotype). Bar = 10 mm

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Fig. 7
figure 7

Microscopic features of Pseudosperma squarrosofulvum (AR-22–024, holotype). a Basidiospores. b Basidia. c Paracystidia. d Cheilocystidia. e Caulocystidia. f Pileipellis. Bars = 10 μm

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MycoBank: MB 851973.

Etymology: The specific epithet refers to the squarrosus (Latin), squarrose; fulvum (Latin), brown-orange pileus.

Holotype: Benin, Atacora Province, Natitingou district, close to Kota Waterfall, on the ground in a gallery forest dominated by Berlinia grandiflora Hutch. & Dalziel and Uapaca guineensis Müll. Arg., at 10°12′43.5″N, 001°26′36.6″E, 500 m asl., 15 June 2022, leg. A. Rühl, C. Manz, D. Dongnima, F. Hampe & S. Sarawi (AR-22–024, STU). GenBank accession numbers PP060395 (ITS), PP060410 (LSU), and PP430970 (RPB2).

Diagnosis: Differs from P. beninense by a brownish-yellow to brown-orange pileus with conical fibrillose to squarrose scales, distinctly larger basidiospores (on av. 12.9 × 6.2 µm), shorter cheilocystidia (on av. 44 × 11 µm), narrow utriform to utriform paracystidia, pileipellis elements with incrusted walls and caulocystidia (up to 60 µm in length), as well as distinct ITS, LSU, and RPB2 sequences.

Description: Pileus 5–12 mm diam., paraboloid to hemispherical, later convex to plano-convex, finally almost applanate, with or without a low small papilla, with deflexed margin when young, later even straight, velipellis absent, colour mostly brownish yellow (2.5Y 7/8–10, 7.5YR 6/8–10) to brown-orange (5YR 5/6–10), gradually darkening towards the centre, with paler margin, the entire surface covered by yellowish ochre (5YR 5/6–8, 4/6) to brownish-yellow (7.5YR 5/6–8), erect, conical scales, with persistent fibrillose veil remnants at the margin. Lamellae moderately crowded, adnexed, ventricose, creamy white to pale yellow when young, becoming light brown with age, margin eroded, whitish. Stipe 8–15 × 0.8–2 mm, central, cylindrical, with subbulbous at the base, cortina not observed, surface whitish to straw-yellow, pruinose only near the apex. Colour of exsiccate: pileus pale dirty straw-yellow to pale yellow–brown, lamellae and stipe whitish. Smell unrecorded.

Basidiospores 11.0–18.0 µm (av. 12.9 µm, SD ± 1.7 µm) × 5.1–8.3 µm (av. 6.2 µm, SD ± 0.6 µm); Q = 1.8–2.6 (av. 2.1, SD ± 0.2) (n = 90 of 1 coll.), mostly oblong to subcylindrical, with guttules, smooth, slightly thick-walled, yellowish brown in 5% KOH. Basidia 25–30 × 8–11 µm, clavate, 4-spored, thin-walled, hyaline or very pale brown in 5% KOH. Cheilocystidia 37–55 µm (av. 44 µm, SD ± 6.0 µm) × 8.5–14 µm (av. 11 µm, SD ± 1.5 µm); Q = 2.9–6.1 (av. 4.2, SD ± 1.0) (n = 40 of 1 coll.), usually oblong, clavate or fusiform, hyaline or very pale yellowish-brown in 5% KOH. Paracystidia 15–35 × 8–17 µm, narrowly utriform to utriform, thin-walled, hyaline or very pale yellowish-brown in 5% KOH. Pileipellis a cutis, formed by cylindrical to fusiform elements with subcapitate to rostrate apex or clavate terminal elements, (35)50–110 × 8–20 µm, often with incrusted walls, yellowish-green in 5% KOH. Caulocystidia (18)35–60 × 8–18 µm, mostly cylindrical or narrowly clavate, in clusters on erect hyphae, with often slightly incrusted walls, pale brownish yellow in 5% KOH. Stipitipellis a cutis of slender, cylindrical hyphae, 5–14 µm wide, thin-walled, colourless in 5% KOH. Clamp connections present in all parts examined.

Habitat and distribution: Basidiomata gregarious, usually terrestrial, on wet and sandy soils, under Berlinia grandiflora and Uapaca guineensis. Hitherto only known from Benin.

Discussion: Phylogenetic analyses of the combined ITS-LSU-RPB2 sequences (Fig. 1) indicate that Pseudosperma squarrosofulvum is closely related to P. stramineum and P. beninense. Morphologically, P. stramineum differs from P. squarrosofulvum by its straw-yellow or buff pileus, a squamulose-squarrose or lanose surface of its pileus, shorter basidiospores (on av. 11.3 × 6.8 µm) with a lower Q-value (Q = 1.7), and broadly clavate to ellipsoid or obovoid paracystidia. P. beninense has a lightly brown to straw brown pileus, a tomentose-lanose to subtomentose surface of its pileus, shorter basidiospores (on av. 12.5 × 7.0 µm), slightly longer cheilocystidia (on av. 51 × 14 µm), cylindrical to broadly clavate paracystidia and longer pileipellis cells reaching up to 220 µm.

Other tropical species with genetic affinities to Pseudosperma squarrosofulvum are P. araneosum, P. brunneosquamulosum, P. rubrobrunneum, P. fulvidiscum, and P. singulare. Morphologically, P. araneosum from tropical Australia differs from P. squarrosofulvum by a strongly radially rimose pileus, notably shorter basidiospores (on av. 10.2 × 6.1 µm), predominantly cylindrical cheilocystidia, absence of caulocystidia, and growth on soil in Melaleuca swamp in lowland tropical mixed forests with Acacia, Corymbia, Eucalyptus and Lophostemon (Matheny and Bougher 2017). Pseudosperma brunneosquamulosum and P. rubrobrunneum, originally described from tropical India, differ from P. squarrosofulvum by significantly shorter basidiospores (on av. 9.0 × 5.9 µm and av. 8.3 × 5.5 µm, respectively), versiform cheilocystidia, and associations with Vateria indica and Hopea ponga, respectively (Tibpromma et al. 2017). Pseudosperma fulvidiscum and P. singulare, recently described from tropical China, differs by shorter basidiospores (on av. 9.3 × 5.6 µm and 9.1 × 6.1 µm, respectively), and an association with trees of Carpinus londoniana var. lanceolata (Hand.-Mazz.) P.C.Li (Zhao et al. 2022).


Pseudosperma stramineum Kaygusuz, Bandini, Rühl, Sarawi, Yorou & M. Piepenbr., sp. nov. (Figs. 8 and 9).

Fig. 8
figure 8

Basidiomata of Pseudosperma stramineum. a Collection AR-22-008 (holotype). b Collection AR-22-009. c Collection AR-22-015. Bars = 10 mm

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Fig. 9
figure 9

Microscopic features of Pseudosperma stramineum (AR-22-008, holotype). a Basidiospores. b Basidia. c Caulocystidia. d Cheilocystidia. e Paracystidia. f Pileipellis. Bars = 10 μm

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MycoBank: MB 851975.

Etymology: The epithet refers to the straw-yellow colour of the pileus.

Holotype: Benin, Borgou Department, Fôret de l'Okpara, on the ground in a savannah forest dominated by Isoberlinia doka, I. tomentosa, Monotes kerstingii and Uapaca togoensis, at 09°14′11.6″N, 002°43′26.0″E, 201 m asl., 12 June 2022, leg. A. Rühl, S. Badou, C. Manz, D. Dongnima, F. Hampe, B. Olou & S. Sarawi (AR-22–008, STU). GenBank accession numbers PP060396 (ITS), PP060411 (LSU), and PP430971 (RPB2).

Diagnosis: Similar to P. amoris Bandini & B. Oertel, but differs by the combination of smaller basidiomata (up to 15 mm in diam.), often squamulose-squarrose pileus surface, larger basidiospores (on av. 11.3 × 6.8 µm), predominantly oblong to narrowly clavate to clavate cheilocystidia, the presence of paracystidia, mostly narrowly cylindrical to narrowly clavate caulocystidia, association with a savannah forest, and by distinct ITS, LSU, and RPB2 sequences.

Description: Pileus 5–15 mm diam., paraboloid to hemispherical when young, later convex to plano-convex, with subumbo to obtuse umbo, undulate with age, with inflexed margin when young, later even deflexed, velipellis absent, colour predominantly straw-yellow (2.5Y 8–7/6) or buff (2.5Y 7/8–10, 6/8), evenly coloured but darker with age, surface felty to lanose, strongly squamulose-squarrose or lanose around the centre with bundles of fibre. Lamellae moderately crowded to crowded, adnexed, (sub)ventricose, yellowish when young, pale brown with age, edge fimbriate to eroded, whitish. Stipe 10–20 × 0.6–1.5 mm, central, cylindrical, usually slightly curved, with subbulbous or distinctly bulbous base, cortina not observed, surface whitish to straw-yellow, pruinose only near the apex. Colour of exsiccate: pileus whitish to pale straw-yellow (2.5Y 8/4–6), lamellae and stipe concolorous. Smell unrecorded.

Basidiospores 10.0–14.0 µm (av. 11.3 µm, SD ± 0.9 µm) × 5.9–8.3 µm (av. 6.8 µm, SD ± 0.5 µm); Q = 1.5–1.9 (av. 1.7, SD ± 0.1) (n = 130 of 3 coll.), mostly oblong, rarely ellipsoid, with guttules, smooth, slightly thick-walled, pale brown to yellowish brown in 5% KOH. Basidia 30–40 × 8.0–11.0 µm, clavate, 4-spored, thin-walled, very pale brown or hyaline in 5% KOH. Cheilocystidia 30–55 µm (av. 40 µm, SD ± 6.6 µm) × 10–20 µm (av. 14 µm, SD ± 1.8 µm); Q = 1.6–4.5 (av. 2.7, SD ± 0.6) (n = 55 of 3 coll.), mostly oblong to narrowly clavate to clavate, thin-walled, pale yellowish-brown in 5% KOH. Paracystidia 20–35 × 10–17 µm, broadly clavate to ellipsoid or obovoid, thin-walled, slightly pale yellowish-greenish in 5% KOH. Pileipellis a cutis, made up of conical, clavate or cylindrical terminal elements with rostrate to obtuse apex, 40–100 × 8–18 µm, walls often strongly incrusted, pale brownish yellow in 5% KOH. Caulocystidia 25–90 × 7.5–15 µm, mostly narrowly cylindrical to narrowly clavate often with slightly incrusted walls, pale brownish yellow in 5% KOH. Stipitipellis a cutis of cylindrical hyphae, 5–12 µm wide, thin-walled, colourless in 5% KOH. Clamp connections present in all parts examined.

Habitat and distribution: Basidiocarps gregarious to subgregarious usually on sandy soils, associated with Caesalpiniaceae (Isoberlinia spp.), Dipterocarpaceae (Monotes kerstingii), and Phyllanthaceae (Uapaca togoensis). Hitherto known from Benin and from environmental sequences of soil samples from West Africa (486ad3d1, 79c39691, and ASV_39).

Additional specimens examined: Benin, Borgou Department, Fôret de l’Okpara, on soil in savannah forest dominated by Isoberlinia spp., Monotes kerstingii and Uapaca togoensis, at 09°14′11.6″N, 002°43′26.0″E, 201 m asl., 12 June 2022, leg. A. Rühl, S. Badou, C. Manz, D. Dongnima, F. Hampe, B. Olou & S. Sarawi (AR-22–009, UNIPAR); ibid., Borgou Department, N'Dali, on soil in savannah forest dominated by Isoberlinia spp., Monotes kerstingii and Uapaca togoensis, at 09°44′38.5″N, 002°41′26.3″E, 350 m asl., 13 June 2022, leg. A. Rühl, C. Manz, D. Dongnima, F. Hampe & S. Sarawi (AR-22–015, UNIPAR).

Discussion: Phylogenetically, Pseudosperma stramineum is closely related to P. squarrosofulvum and P. beninense, but these species form three independent lineages nested in a tropical subclade of Pseudosperma (MLB = 100%, BPP = 1.0, Fig. 1). Pseudosperma squarrosofulvum differs from P. stramineum by its brownish yellow to brown-orange pileus, conical fibrillose scaly pilei surface with yellow ochre to brownish yellow tinge, longer basidiospores (on av. 12.9 × 6.2 μm), narrowly utriform to utriform paracystidia, and shorter caulocystidia (18–60 × 8.0–18 μm). Pseudosperma beninense has a tomentose-lanose to subtomentose pileus surface, mainly (sub)amgydaliform basidiospores with an acute apex, longer cheilocystidia (on av. 51 × 14 μm) and longer pileipellis elements (up to 220 μm in length).

Based on the ITS-LSU-RPB2 phylogeny, Pseudosperma stramineum is also somewhat related to further tropical Pseudosperma species, namely P. araneosum and P. gracilissimum from Australia (Matheny and Bougher 2017), P. brunneosquamulosum, P. rubrobrunneum and P. luteobrunneum (K.P.D. Latha & Manim.) Matheny & Esteve-Rav. from India (Tibpromma et al. 2017), and P. fulvidiscum and P. singulare from China (Zhao et al. 2022). Apart from different geographical locations and different plant associations, Pseudosperma stramineum is easily distinguished from these species by its significantly longer basidiospores, which are av. 11.3 × 6.8 µm.

Pseudosperma notodryinum (Singer, I.J.A. Aguiar & Ivory) Matheny & Esteve-Rav., described from tropical Costa Rica, differs from P. stramineum by a brown to umbrious pileus with a distinct umbo, a slender stipe, shorter basidiospores (on av. 7.0–9.0 × 4.0–5.0 μm), and a habitat in Quercus oleoides Schltdl. & Cham. forests (Singer et al. 1983).

Further species morphologically similar to Pseudosperma stramineum in terms of the pileus colour are P. amoris, P. flavellum (P. Karst.) Matheny & Esteve-Rav. and P. minervae Bandini & G. Bandini. Pseudosperma amoris, described from Germany, differs from P. stramineum by the presence of a velipellis, and shorter basidiospores (on av. 10.3 × 6.2 μm) (Bandini and Oertel 2020). The European species Pseudosperma flavellum has shorter basidiospores (on av. 10.6 × 4.9 μm), mostly (sub)cylindrical to subutriform cheilocystidia, and no paracystidia (Karsten 1889; Bandini and Oertel 2020). Pseudosperma minervae, recently described from Germany, has a rimulose pileus, shorter basidiospores (on av. 10.4 μm in length) and generally (sub)clavate cheilocystidia (Bandini et al. 2023). These species are genetically very distant from Pseudosperma stramineum (Fig. 1).


Pseudosperma tiliae Kaygusuz, Bandini, Rühl, Sarawi, Yorou & M. Piepenbr., sp. nov. (Figs. 10 and 11).

Fig. 10
figure 10

Basidiomata of Pseudosperma tiliae in the field. a Collection OKA-TR3501 (holotype). b Collection OKA-TR3502. c Collection OKA-TR3503. Bars = 10 mm

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Fig. 11
figure 11

Microscopic features of Pseudosperma tiliae (OKA-TR3501, holotype). a Basidiospores. b Basidia. c Cheilocystidia. d Paracystidia. e Pileipellis. f Caulocystidia. Bars = 10 μm

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MycoBank: MB 851976.

Etymology: The specific epithet refers to Tilia, the genus of the trees, which are probably ectomycorrhizal (ECM) partners of this fungal species.

Holotype: Turkey, Isparta Province, Atabey district, İslamköy village, on soil under Tilia platyphyllos, at 37°56′11.0″N, 30°38′46.9″E, 1000 m asl., 17 June 2022, leg. O. Kaygusuz (OKA-TR3501, ISUF). GenBank accession numbers PP060399 (ITS), PP060414 (LSU), and PP430974 (RPB2).

Diagnosis: Similar to P. mediterraneum, but differing by basidiomata with a broad subumbo, pale yellow to chrome yellow pileus often with brownish-red tinge at the centre, somewhat smaller basidiospores measuring on average 12.5 × 7.0 μm (on av. Q = 1.8), distinctly longer cheilocystidia (on av. 57 × 14 μm), association with Tilia platyphyllos, and by distinct ITS, LSU, and RPB2 sequences.

Description: Pileus 30–45 mm diam., paraboloid to hemispherical when young, later convex, with low broad umbo, margin first often inflexed, later even deflexed or straight, with abundant remnants of a dingy whitish velipellis, colour predominantly pale yellow or chrome yellow (5Y 8/4–8, 2.5Y 7–5/6), transitioning to brown towards the centre, (5YR 5–4/6), often with dark brown to brownish-red tinge at the centre (10R 4/4–8), outwards paler, background whitish to whitish yellow towards the margin, surface dry, mate, appressed fibrillose and strongly rimose, splitting deeply radially, velipellis mostly present as a whitish to dingy whitish patch in the centre of the pileus, fugacious or not. Lamellae moderately crowded to crowded, adnexed, (sub)ventricose, at first creamy white or dingy whitish, then with a faintly orange tint, brownish when old, edge fimbriate to eroded, whitish. Stipe 35–50 × 4–10 mm, central, cylindrical, straight or sometimes curved at the base, with equal diam. but sometimes widened to subbulbous at the base, cortina not observed, surface whitish to ivory, covered by light orange-brown (7.5YR 7/4–6) fibrils downwards, pruinose near the apex, with white particles like the remains of a volva at the base. Colour of exsiccate: pileus whitish to ivory, lamellae and stipe concolorous or slightly lighter, slightly darker on drying. Smell faintly spermatic.

Basidiospores 10.0–14.5 µm (av. 12.5 µm, SD ± 1.4 µm) × 6.0–8.0 µm (av. 7.0 µm, SD ± 0.5 µm); Q = 1.4–2.3 (av. 1.8, SD ± 0.2) (n = 150 of 3 coll.), mostly oblong, rarely ellipsoid, sometimes with slight suprahilar depression, with guttules, smooth, slightly thick-walled, pale brown to brown in 5% KOH. Basidia 25–45 × 10–15 µm, clavate, generally 4-spored, rarely 2-spored, thin-walled, hyaline in 5% KOH. Cheilocystidia 45–75 µm (av. 57 µm, SD ± 1.5 µm) × 10–18 µm (av. 14 µm, SD ± 1.1 µm); Q = 2.8–5.8 (av. 4.3, SD ± 0.9) (n = 47 of 3 coll.), mostly narrowly clavate to clavate or narrowly utriform, with rounded apex, sometimes cylindrical, in clusters, thin-walled, pale yellowish-greenish in 5% KOH. Paracystidia 20–35 × 9–14 µm, fusiform, narrowly utriform, ellipsoid or subglobose, sometimes divided by septa, thin-walled, pale yellowish-greenish in 5% KOH. Pileipellis a cutis, composed of narrowly fusiform or cylindrical cells with acute to obtuse apex, with somewhat ascending terminal elements, 100–330 × 8–20 µm, thin-walled, pale brownish yellow in 5% KOH. Caulocystidia 50–90(120) × 6–14 µm, mostly narrowly clavate to cylindrical, sometimes with mucronate apex, thin-walled, hyaline. Stipitipellis a cutis of cylindrical hyphae, 3–10 µm wide, thin-walled, colourless in 5% KOH. Clamp connections present in all parts examined.

Habitat and distribution: Basidiocarps subgregarious, usually on humus-rich soils, from early to late June, generally present at 1000 m asl., under Tilia platyphyllos. Currently known from the Mediterranean region of Turkey.

Additional specimens examined: Turkey, Isparta Province, Çünür district, Süleyman Demirel University East Campus, on soil under T. platyphyllos, at 37°49′43.3″N, 30°32′24.3″E, 1020 m asl., 04 June 2023, leg. O. Kaygusuz (OKA-TR3502, ISUF); ibid., Atabey district, around Atabey-İslamköy road, on soil under T. platyphyllos, at 37°53′45.1″N, 30°37′40.2″E, 1005 m asl., 12 June 2023, leg. O. Kaygusuz (OKA-TR3503, ISUF); ibid., Aksu district, on soil under T. platyphyllos, at 37°48′40.2″N, 31°05′22.7″E, 1210 m asl., 21 June 2023, leg. O. Kaygusuz (OKA-TR3504, ISUF).

Discussion: In the concatenated ITS-LSU-RPB2 phylogeny (Fig. 1), Pseudosperma tiliae is sister to P. mediterraneum and nested with P. holoxanthum (Grund & D.E. Stuntz) Matheny & Esteve-Rav., P. melliolens (Kühner) Matheny & Esteve-Rav., P. rimosum (Bull.) Matheny & Esteve-Rav., and P. sororium (Kauffman) Matheny & Esteve-Rav. However, morphologically P. mediterraneum, originally described from Italy, differs from P. tiliae by a pale buff to ochraceous pileus, slightly longer basidiospores (on av. 13.2 × 6.6 µm) with a higher Q-value (Q = 2), shorter cheilocystidia (36–57 × 13–26 µm), and a habitat on dune sand associated with Pinus pinea (Kuyper 1986). The genetic distance between Pseudosperma tiliae and P. mediterraneum is 3%, corresponding to 18 base divergences in 600 nucleotides, indicating that these are different species. Pseudosperma holoxanthum, originally described from the USA, differs from P. tiliae by a longer (up to 100 mm in length) and pale yellow to straw yellow stipe, shorter basidiospores (9.0–13.0 × 6.0–8.0 µm), longer cheilocystidia (up to 110 µm in length), and growth with conifers (Grund and Stuntz 1981). Pseudosperma melliolens differs by a brown to brownish coloured pileus, greyish or reddish stipe, shorter basidiospores (9.0–13.5 × 6.0–8.0 µm) and shorter cheilocystidia (up to 55 µm in length) (Kühner 1988). Pseudosperma rimosum differs by usually less stout habitus, often dull fallow pileus colour, only faint and fugacious greyish velipellis (Bulliard 1789). Pseudosperma sororium, originally described from the USA, has larger basidiomata (up to 70 mm in diam.) with a subconical to conical-campanulate pileus, and distinctly longer basidiospores (9.0–16.0 × 5.0–8.0 µm) (Murrill et al. 1924).

Other European species that are morphologically similar to Pseudosperma tiliae are P. arenicola (R. Heim) Matheny & Esteve-Rav., P. mimicum (Massee) Matheny & Esteve-Rav., P. musilii Bandini, B. Oertel & Schmidt-Stohn, P. pamukkalense Kaygusuz, Bandini & Knudsen, P. pseudoorbatum (Esteve-Rav. & García Blanco) Matheny & Esteve-Rav, and P. spectrale Bandini & B. Oertel. Pseudosperma arenicola differs by larger pileus (up to 68 mm in diam.) and stipe (up to 75 mm long), distinctly longer basidiospores (on av. 13–15.4 × 6.3–8.0 µm), longer (up to 105 µm) and mostly cylindrical cheilocystidia, cylindrical caulocystidia, and a habitat associated with Salix repens L, Populus canadensis Moench, or sometimes Pinus maritima Mill. (Kuyper 1986). Pseudosperma mimicum differs by larger pileus (up to 80 mm in diam.), yellow–brown lamellae, much longer basidiospores (14.0–16.0 × 6.0–8.0 µm), and the absence of cystidia (Massee 1904). Pseudosperma musilii differs by its dingy straw to dark brown pileus with a strongly rimose surface, shorter basidiospores (on av. 11.3 × 6.7 µm), and shorter cheilocystidia (on av. 48 × 12 µm) (Bandini et al. 2023). Pseudosperma pamukkalense differs by subphaseoliform basidiospores, a predominant association with Pinus nigra subsp. pallasiana (Lamb.) Holmboe, and genetic differences (ITS locus 81.5% identity) (Kaygusuz et al. 2023). Pseudosperma pseudoorbatum has a white to ivory-white pileus, notably longer basidiospores (on av. 14.6 × 7.1 µm), and a habitat with Pinus forests (Pinus pinaster Aiton and P. pinea L.) (Esteve-Raventós et al. 2003). Pseudosperma spectrale has a whitish to straw-coloured pileus, slightly shorter basidiospores (on av. 12.1 × 7.0 µm), and a habitat with conifers (Bandini et al. 2022).

Conclusions

It was previously suggested that species of Inocybaceae began to spread over large areas of northern and southern South America, Australia, and New Zealand during the Palaeogene or later periods (Matheny 2009; Matheny et al. 2009). Recent multi-gene phylogenetic analyses confirmed close affinities between Pseudosperma taxa from tropical Asia, tropical Australia, and tropical China (Zhao et al. 2022). Similarly, in the present study, phylogenetic analyses generated from the combined ITS, LSU, and RPB2 dataset revealed rather close phylogenetic relationships among Pseudosperma species indigenous to the tropical regions of Benin, Australia, India, and China. The new species Pseudosperma beninense, P. cremeo-ochraceum, P. squarrosofulvum, and P. stramineum were found in ectomycorrhizal forests with tropical climate of Benin and are phylogenetically close to each other in a subclade that in addition to the species from Benin includes five further species from tropical regions of the palaeotropics and Australia. These five species are P. araneosum from Australia (Matheny and Bougher 2017), Pseudosperma brunneosquamulosum and P. rubrobrunneum from India (Tibpromma et al. 2017), and Pseudosperma fulvidiscum and P. singulare from China (Zhao et al. 2022). The ongoing discovery and characterization of tropical to subtropical taxa within the genus will improve our understanding of their biogeographical distribution and evolutionary history.