A Taxonomic and Phylogenetic Contribution on Inosperma Section Inosperma (Agaricales, Inocybaceae) in Europe: Calamistratum and Geraniodorum Groups

The aim of this study is to carry out a taxonomic revision of the groups Calamistratum and Geraniodorum of the genus Inosperma sect. Inosperma in Europe. For this purpose, a multigenic phylogenetic analysis was carried out using the ITS, LSU, RPB1 and RPB2 markers, covering a total of 111 sequences, including those generated from the existing type-material collections. This analysis led to the recognition of nine clades or terminal groups for the European continent, correlating with nine morphological species. Three of them, I. calamistratum, I. neohirsutum sp. nov. and I. turietoense sp. nov., are distributed in humid and temperate forests, whereas I. geminum sp. nov., I. geraniodorum, I. gracilentum sp. nov., I. praetermissum comb. nov., I. subhirsutum and I. veliferum seem to be restricted to the colder altimontane, boreal and alpine climates. It is concluded that the study of morphological and ecological characteristics allows the recognition of species without the need for an often-subjective interpretation of organoleptic characteristics. Inocybe hirsuta is considered a synonym of Inosperma calamistratum, Inosperma praetermissum as a different species from I. calamistratum, and Inocybe geraniodora var. gracilenta f. salicis-herbaceae as a synonym of I. praetermissum. Four new species and one new combination are proposed. A key for the recognition of the European species is provided. Illustrations and photographs of macro- and micromorphological characters and SEM spores of all species are presented.


Introduction
The genus Inosperma (Kühner) Matheny & Esteve-Rav. is currently one of the seven genera that form part of the family Inocybaceae Jülich [1], a monophyletic and cosmopolitan family, with ectomycorrhizic representatives that live in symbiotic association with a total of 23 vascular plant families [2].The estimated number of species of Inocybaceae worldwide is well over a thousand [3], with Europe and North America being the areas with the best representation and understanding of their diversity.
The species of the genus Inosperma are characterised by the absence of pleurocystidia and often a marked reddening of the context and very distinctive odours (earthy, fishy, aromatic, fruity, pelargonium, truffle-like, etc.).More than 55 species are known worldwide, distributed on all continents except South America [2].Until the recognition of Inosperma as a genus, its species were grouped in several sections of the genus Inocybe (Fr.) Fr. subgenus Inosperma Kühner [4,5].Among these sections or groups, two are well represented in the Northern Hemisphere and correspond to (1) the Cervicolores group or clade (= Inocybe subg.Inosperma section Cervicolores Kühner & Romagn.ex Singer) and (2) the Maculata group or clade (= Inocybe subg.Inosperma sect.Rimosae (Fr.) Quél.sensu Larsson et al. 2009 pro parte).The genus Inosperma also includes two evolutionary lineages that are still poorly known in tropical Asia and Africa [2].
Inosperma is widely represented in Europe and North America, comprising about 35-40 species [2], while about 15 more have been described from Asia and Australasia, according to Latha and Manimohan [6] and Matheny and Bougher [7].The Cervicolores group/clade is represented by species characterised by a usually very pronounced reddening of the context; a fibrillose, woolly, tomentose, scaly or strigose pileus; and very slender (Q > 4.0) and necropigmented basidia.The Maculatae group/clade includes species which differ greatly in appearance from the former, as they usually show little or no reddening at all, the pileus is smooth and radially fibrous to rimose, and the basidia lack necropigment and are not as slender (Q < 4.0).The Maculatae were traditionally considered to be part of the section Rimosae of Inocybe subg.Inosperma [4,5,8] due to the smooth, rimose appearance of the pileus and their hardly reddening flesh.However, following the study of Matheny et al. [2], based on a six-gene phylogeny, it has been shown that the traditional section Rimosae should be integrated into the genus Pseudosperma Matheny & Esteve-Rav., as its species are phylogenetically rather distant from Inosperma.Bizio [9] offers a detailed historical review of the different treatments of these two groups of Inocybe.
In this contribution, we present a taxonomic and phylogenetic study of part of the Inosperma species present in Europe, specifically two groups that we have named Calamistratum and Geraniodorum.Both have traditionally been part of Inocybe sect.Cervicolores, which was proposed invalidly by Kühner and Romagnesi [10] and later validated by Singer [11].The same treatment was subsequently adopted by Kuyper [4] in his European monograph on the smooth-spored Inocybe.As mentioned above, based on the phylogenetic study by Matheny et al. [2], the Cervicolores should now correspond to the section Inosperma of the genus Inosperma with the type species Inosperma calamistratum (Fr.)Matheny & Esteve-Rav.
Bon [5] considered two groups or tribes (Bongardii and Calamistrata) for the Cervicolores, which, according to the author, can be distinguished by the intensity of the flesh reddening, the colour of the basidiomata and the spore Q-value.Most species of the Calamistratum group can be easily recognised macroscopically by the blue-greenish shades on the stipe and the strigose-squamose appearance of the pileus surface; on the other hand, the species of the Geraniodorum group lack this striking colouration and are characterised by their small to very small size, a distinctive pelargonium or geranium-like odour, their preference for high mountain and boreal/alpine habitats, and the fibrillose, sometimes subsquamose appearance of the pileus.In this respect, the Geraniodora members may be reminiscent of other Inosperma species, referred to here as the Cervicolor group, containing well-known species like Inosperma cervicolor (Pers.)Matheny & Esteve-Rav.and I. bongardii (Weinm.)Matheny & Esteve-Rav., but these generally have a larger size, thrive in more mesophilic habitats and emit different types of odours (earthy, aromatic and fishy).The phylogenetic results obtained by Larsson et al. [8] and Kropp et al. [12] suggest that the section Cervicolores constitutes a monophyletic group, although the phylogenetic tree generated in this study does not corroborate these conclusions, probably due to a high amount of missing data.One of the new species presented here, Inosperma turietoense Pancorbo & Esteve-Rav., shows a clear morphological resemblance to the Cervicolor members but is phylogenetically closer to members of the Geraniodorum group.A sequel to this work, which deals with the Cervicolor group, is currently in preparation by the authors.
In recent years, only a few new species have been described in Europe, all belonging to the Cervicolor and Maculata groups.These include I. vinaceum Cervini, M. Carbone & Bizio [13] in the Maculata group; another in the Cervicolor group, namely, Inosperma monastichum Bandini & B. Oertel [14]; I. dodonae Bandini & B. Oertel and I. ismeneanum Bandini & B. Oertel [14], which belong to the Maculata group; and, finally, Inosperma apollonium [15], which also belongs to the Maculatae.Based on our data, the Cervicolor group currently consists of five species in Europe.There are an additional five species that are currently being studied (Esteve-Raventós et al., in preparation).On the other hand, the Maculata group currently comprises about 12-14 species in Europe.
Among the European Inosperma species, I. erubescens A. Blytt (= Inocybe patouillardii Bres.) has traditionally been considered toxic due to its muscarine content [16,17].Quite recently, several articles have pointed to the presence of various toxic substances in Inosperma species with tropical distribution in Asia, specifically because of their muscarine content, such as Inosperma virosum (C.K. Pradeep, K.B. Vrinda & Matheny) Matheny & Esteve-Rav.[18], I. muscarium Y.G.Fan, L.S. Deng, W.J. Yu & N.K. Zeng, I. hainanense Y.G.Fan, L.S. Deng, W.J. Yu & N.K. Zeng [19] and I. zonativeliferum Y.G.Fan, H.J. Li, F. Xu, L.S. Deng & W.J. Yu [20].All these species belong to the two tropical evolutionary lineages mentioned above.Li et al. [21] demonstrated the presence of different neurotoxins in some species of Inosperma described from tropical China, although with different quantitative levels depending on the species; the presence of muscarine was detected in I. nivallelum S.N.Li These results support the opinion of Stijve et al. [22], who stated that some groups of Inocybe are characterised by the complete absence of muscarine, including sect.Cervicolores.

Morphological Analyses
Specimens were photographed in the field with several digital cameras.After observation, fresh specimens were air-dried in a food dehydrator.Samples of specimens were rehydrated in aqueous ammonia solutions to examine anatomical features, such as cystidia, basidia and basidiospores, and observed by light microscopy.Drawings were made with the aid of a Zeiss drawing tube under an oil-immersion objective and then converted to vectors with ADOBE ILLUSTRATOR v. 25.4.1 (www.adobe.com/es/products/illustrator.html, accessed on 1 January 2024).Munsell Soil Color Charts (1994 revised edition, New York, NY, USA) were used as colour references in the macroscopic descriptions.Photographs and measurements of microscopic structures were taken with a Nikon D90 camera attached to a Nikon 55i microscope (Isaza, S.A., Nikon Spain, Barcelona, Spain) controlled with CAMERA CONTROL PRO2 v. 2.7.0 software (www.nikon.es_ES/product//apps-software/camera-control-pro-2-full-version,accessed on 1 January 2024) and subsequently retouched in ADOBE LIGHT-ROOM v. 6.14 (https: //www.adobe.com/es/products/photoshop-lightroom.html,accessed on 1 January 2024) and PIXIMÈTRE v. 5.10 R1541 software (www.piximetre.fr,accessed on 1 January 2020).Measurements of microscopic structures are given as (a-)b-c(-d), where a = minimum value, b = 5% percentile, c = 95% percentile, d = maximum value, and a subscript avg to indicate average values.Q-values are ratios of spore length to spore width and were calculated for each spore.The total number of spores measured (x) and the number of specimens sampled (y) are indicated as (x/y).Scanning electron micrographs (SEMs) were obtained with a Zeiss DSM-950, applying the critical point technique described in Moreno and Oltra [23].Specimens studied have been collected in several European countries: Andorra, Finland, France, Italy, Norway, Portugal, Spain, Sweden and Switzerland.Collections were accessioned at the Herbarium of the University of Alcalá de Henares (AH) and the University of Gothenburg Herbarium (GB), with duplicates of some of them kept in the private herbaria of E. Bizio (EB), E. Larsson (EL), E. Rubio (ERD), F. Pancorbo (FP), R.J. Ferrari (FRJ), J. Ballará (JB), J. Vauras (JV) and J. Vila (JVG).Loans of specimens were obtained from the Sociedad de Ciencias Aranzadi (ARAN), the Conservatoire et Jardin Botanique de Genève (G), the University of Helsinki (H), the Naturwissenschaftlichen Sammlungen of the Tiroler Landesmuseum (IBF), the Museo di Storia Naturale di Venezia (MCVE) and the University of Turku (TUR).Herbarium codes follow Thiers [24].Terminology follows Vellinga [25] and Kuyper [4].
PCR reactions were prepared using a Master Mix (Qiagen Multiplex PCR Kit) in a 20 µL volume, and then reactions were conducted in a GeneAmp ® PCR System 9700 Thermal Cycler (Applied Biosystems, San Francisco, CA, USA).The amplification programme for the ITS and LSU regions was as follows: initial denaturation at 95  C for 1 min; followed by a final extension at 72 • C for 10 min.PCR amplifications of the RPB1 and RPB2 regions followed O'Donnell et al. [33] and Hansen et al. [34], respectively.PCR products were visualised in a 1% agarose gel and stained with SYBR Safe DNA Gel Stain (Invitrogen-Thermo Fisher Scientific, Inc., Waltham, MA, USA), using a UV trans-illuminator.PCR products were purified using Exo-sap-IT (USB Corporation, Santa Clara, CA, USA) and then sequenced at the Molecular Biology Service of Alcalá University.The generation of ITS and LSU sequence data at the University of Gothenburg followed the methods described in Nitare et al. [35].
Sequences were edited and assembled in SEQUENCHER v. 4.10.1 (Gene Codes Corp., Ann Arbor, MI, USA) and deposited in GenBank (Table 1).Additional sequences were downloaded from GenBank.Nucleotide sequences of each region were automatically aligned in ALIVIEW [36] and then manually adjusted.Protein-coding genes were translated to amino acids to determine intron positions.To check gene congruence, each region was analysed in IQ-TREE, starting from a random tree under default options.To assess the branch confidence, 1000 ML bootstrap replicates were conducted using ultrafast bootstrapping.Gene congruence was assessed by comparing supported clades among single-gene genealogies [37].Clades were considered in conflict if a supported clade (ML-BP ≥ 95%) for one marker was contradicted with significant support by another one.Since no conflicts were detected, the four markers were concatenated.Introns were included, and the third codon position was partitioned in the RPB1 and RPB2 regions.Ten partitions were set: ITS1, 5.8S, ITS2, LSU, RPB1 (1st and 2nd positions), RPB1 (3rd position), RPB1 introns, RPB2 (1st and 2nd positions), RPB2 (3rd position) and RPB2 introns.
Maximum likelihood (ML) analysis was carried out in IQ-TREE [38], starting from a random tree under default options.To assess the branch confidence, 1000 ML bootstrap replicates were conducted using standard bootstrapping.Bayesian analysis was conducted in MRBAYES v. 3.2.7a[39], in the CIPRES Science Gateway [40], using two parallel runs of 4 Metropolis-coupled Markov chain Monte Carlo (MCMCMC) chains for 20 M generations, starting from a random tree, and sampling one tree every 100 generations from the posterior distribution.Substitution models were sampled across the GTR space during the MCMC simulation [39].Stationarity was assumed when the average standard deviation of split frequencies fell below 0.01.The burn-in fraction was set to discard 0.25 trees from each analysis.To assess the branch confidence, a 50% majority rule consensus tree was computed with the remaining trees using the SUMT command of MRBAYES.An ML stan-dard bootstrap (ML-Boot) ≥ 70 or Bayesian posterior probability (PP) values ≥ 0.95 were considered supported.
The ML analysis of the combined dataset resulted in a single best ML tree of −lnL = 12,847,950.The Bayesian analysis reached average standard deviations of split frequencies > 0.01 after 12,195,000 generations.The Bayesian majority rule consensus tree is shown in Figure 1, with bootstrap support values and Bayesian posterior probabilities by nodes.The backbone of the tree is overall not supported, but shallow clades corresponding to I. neohirsutum (ML-Boot 98, BPP 1), I. calamistratum (ML-Boot 98, BPP 1), I. gracilentum (ML-Boot 99, BPP 1), I. veliferum (ML-Boot 98, BPP 1), I. geraniodorum (ML-Boot 78, BPP 0.89), I. turietoense (ML-Boot 96, BPP 1) and I. praetermissum (ML-Boot 89, BPP 0.99) received support in at least one analysis among European taxa.The clade encompassing samples assigned to I. subhirsutum showed a rather high sequence divergence and was not supported (ML-Boot 61, BPP 0.53), but a smaller clade within it containing five samples from Northern Europe was supported in the Bayesian analysis (ML-Boot 63, BPP 0.98).A larger clade comprising sequences of I. subhirsutum and I. neohirsutum and sequences from North America identified as I. apiosmotum, I. hirsutum var.maximum and I. calamistratum was also supported in the Bayesian analysis (ML-Boot 44, BPP 0.98).

1.
Inosperma calamistratum (Fr.)Descriptions and selected iconography.Konrad and Maublanc ([45], pl 89, 90), Bresadola ([46], pl 720 Figure 1 Distribution.Based on the data obtained in our study, I. calamistratum is widespread throughout Europe, as also suggested by Courtecuisse and Duhem [55], although it is not as common as it has been considered until now.The high number of observations and records of this species may be due to its apparent ease of recognition, based on its colouration and the appearance of the surfaces of the pileus and stipe.Most records reported from the northern boreal to alpine zones do not correspond to I. calamistratum but probably refer to I. praetermissum, I. gracilentum and I. subhirsutum.Furthermore, records from similar bioclimatic areas may correspond to I. neohirsutum, with which it is more easily confused. There are no records in the GenBank and UNITE databases referring to other continents, such as North America and Asia (Matheny, pers.comm.).The only record matching the sequence obtained from the neotype corresponds to AM882938 (EL 19-04, GB 0240829), from Sweden.The deposited sequences matching other similar species, especially I. praetermissum and I. subhirsutum, are more frequent.
Notes.Inosperma calamistratum (≡ Agaricus calamistratus Fr.) is the type of the genus Inosperma (Kühner) Matheny & Esteve-Rav.[2].Because of its morphological and ecological peculiarities, it is easy to recognise and has been frequently recorded in Europe.The surface of the pileus and stipe is characteristically scaly-hirsute, even squarrose (Figure 9A-C).The blue-green colour at the base of the stipe is also very distinctive, although this character can vary with environmental conditions, age and degree of imbibition of the basidiomata.Microscopically, the narrow spores show a marked tendency to be phaseoliform in profile (Figure 2A,D), and the lamellar edge consists of numerous claviform to subcylindrical, twoto three-septate cheilocystidia, barely longer than 40 µm (Figure 2C), mixed with some basidia, often greenish pigmented.Its odour is very peculiar and variable, and it has been defined in different ways in the literature, such as rancid, resinous, sour, reminiscent of fish or with a sweet fruity component.In any case, it is not like that of pelargonium, which is also present in other related species, especially those defined here as the Geraniodorum group.Based on the results of our study, we are convinced that I. calamistratum has often been confused with other species, and its presence in northern boreal to alpine zones seems most likely to be excluded in view of the results obtained.Records from high altitudes and boreo-alpine latitudes correspond to other morphologically very close species that have been identified in the past as ecological forms or variants of I. calamistratum ([65]: 77).
On the European continent, I. calamistratum shares similar or common habitats with I. neohirsutum, and both occur in moist temperate forests of Fagaceae (Fagus, Quercus and Castanea), coniferous or mixed.Morphologically they are also similar in appearance, although I. calamistratum often produces larger basidiomata, with a longer, slender and elastic stipe (30-80 × 2-8 mm), the scales of the pileus and stipe are thinner and often recurved, giving it a hirsute to squarrose appearance, and are usually distributed over the entire surface as they develop.In I. neohirsutum, the scales are conspicuously aggregated on the central part of the pileus during development, then appear thicker as they tend to fuse and take on a pyramidal appearance.There are also differences in spore Q, and although both have a clear tendency to be phaseoliform in profile, I. neohirsutum has slightly wider spores with a lower Q (Q avg 1.7 vs. 2.0).Other species of similar appearance, such as I. gracilentum, I. praetermissum and I. subhirsutum, show differences in spore shape and size, inhabit different ecosystems and are well-separated phylogenetically (Figure 1).
There are several morphologically similar species in North America, but they are all distinct phylogenetically [12,66] Also similar in appearance to I. calamistratum are the species Inosperma longisporum, I. squamulosobrunneum and I. squamulosohinnuleum.These have been recently described from China, from montane coniferous forests in subtropical environments.All three species show macroscopic and microscopic differences from I. calamistratum and phylogenetic characters closer to North American species than to European species [21].Other similar species, especially in pileus and stipe cover, have been recorded from the Australian continent and Southeast Asia, e.g., Inosperma calamistratoides (E.Horak) Matheny & Esteve-Rav.and Inosperma latericium (E.Horak) Matheny & Esteve-Rav., but with different micromorphological characters and rather distant phylogenetically [7,67,68].Diagnosis.Inosperma gracilentum differs from other morphologically similar species such as I. praetermissum and I. calamistratum by the long ellipsoid spores, which are slightly concave and sometimes slightly phaseoliform in lateral view, and by the shorter cheilocystidia.It is phylogenetically distinct from all other species of the Calamistratum group.
Holotype.SWEDEN, Åsele lappmark, Vilhelmina, Klimpfjäll, Frimstjakke: 65 Description.Pileus 5-25 mm; when young, hemispherical, conical to obtuse conical with recurved margin; later, conico-convex to plano-convex; surface dry, margin fibrillose to finely scaly, centre of disc scaly to recurved scaly, ochraceous brown to reddish brown, velipellis ochraceous, sometimes not observed or only present in centre of pileus, fugacious.Lamellae rather sparse, broadly adnate to emarginate (L = 26-40), interspersed with lamellulae, initially pale beige, turning ochraceous brown with age, edge pale fimbriate.Stipe 15-30 × 1-3 mm, dry, equal to slightly bulbous, at the base bluish green, more ochraceous brown at apex, fibrillose, squamulose, flocculose at apex.Context ochraceous brown and bluish green at the base of stipe and in the middle of the pileus, more or less reddish on the upper part of the stipe when cut.Odour distinctly of pelargonium or fishy.Basidiospores variable, (10.2-)10.8-13.7(-14.4)× 6.0-7.4(-7.7)µm, Sp avg = 12.1 × 6.5 µm, Q = (1.63-)1.70-2.04(-2.08),Q avg = 1.8 (n = 67/1), smooth, ochraceous brown, long ellipsoid, some adaxially plane to slightly concave, typically depressed in the supra-apicular region (Figure 3B,F), with obtuse apex, apiculus small and not distinct.Basidia Distribution.Known only from the alpine areas of Europe in Sweden and Switzerland, where its presence is confirmed by molecular data.Its distribution range may be wider; however, the species seems to be rare, and few confirmed collections are known.There are no ITS sequences in GenBank nor in the UNITE database that match or are close to the samples studied.
Ecology.Found growing in the alpine zone on calcareous soils among Salix reticulata, S. retusa, Dryas octopetala and Bistorta vivipara.
Etymology.Refers to the Latin word gracilentus, which means slender, thin.Additional specimens examined.SWITZERLAND, Grisons, National Park, between Sur il Foss and Alp Minger: 46 Notes.Favre ([69]: 84) very briefly described a "varieté gracilenta" for Inocybe geraniodora, and the voucher collection (Figure 4) was examined by us (G!).This variety was not validly published by Favre because no Latin diagnosis was given (nom.inval., Art 39.1).Favre's collection, based on the molecular data obtained, represents the same taxon as the Swedish holotype proposed here.It is a distinct species from Inosperma geraniodorum.
The holotype includes many specimens that have been examined in detail for their macro-and micromorphological characters, and ITS-LSU sequences were successfully obtained.Inosperma gracilentum is similar to I. praetermissum in morphological characters and habitat.It differs in the spores, which are broader with an ellipsoid and more regular outline, often adaxially slightly concave to hardly subphaseoliform, often depressed in the supra-apicular region (Figure 3B,F).The cheilocystidia are also much shorter in I. gracilentum, barely exceeding 35 (-40) µm in length (Figure 3D).From the available data, it seems to be a rare species, and to us it is only known from two alpine localities in Europe.Inosperma praetermissum is more widespread in the Northern Hemisphere in the boreal zone and is also known from North America and Asia.Inosperma gracilentum can also resemble I. subhirsutum and the two can easily be confused, but they are genetically distinct (Figure 1).Both show a different appearance of the pileus and stipe surface, which is often more fibrillose and lanose ("mallocyboid") in I. subhirsutum and more hirsute-strigose in I. gracilentum.Both can be separated in terms of micromorphology by the spore measurements, since I. gracilentum has narrower spores (Q avg = 1.8) than I. subhirsutum (Q avg = 1.6).Inosperma subhirsutum has more regular ellipsoid to ovo-ellipsoid spores, often flattened in profile (more reminiscent of the spores of I. geraniodorum), it has longer cheilocystidia and is collected more frequently and regularly in the alpine zone of the Alps and Fennoscandia.
fibrillose and lanose ("mallocyboid") in I. subhirsutum and more hirsute-strigose in I. gracilentum.Both can be separated in terms of micromorphology by the spore measurements, since I. gracilentum has narrower spores (Qavg = 1.8) than I. subhirsutum (Qavg = 1.6).Inosperma subhirsutum has more regular ellipsoid to ovo-ellipsoid spores, often flattened in profile (more reminiscent of the spores of I. geraniodorum), it has longer cheilocystidia and is collected more frequently and regularly in the alpine zone of the Alps and Fennoscandia.Description.Pileus 15-25(-30) mm; when young, hemispherical convex to campanulate, sometimes obtusely conical, with deflexed, wavy margin; later, conico-convex to planoconvex, sometimes with a slightly depressed centre; dry, not hygrophanous, margin crenate; surface fibrillose-lacerate to finely scaly towards the edge, strongly scaly and hirsutesquarrose on the disc, formed by clusters of recurved concolourous scales, these often aggregated and coarse in the centre, sometimes appearing as pyramidal aggregates with age.Colour uniformly brown to chocolate brown on a lighter background as the surface breaks into scales; velipellis not observed.Lamellae moderately dense (L = 30-40), narrowly adnate to emarginate, subventricose, interspersed with numerous lamellulae l = 1-2(-3), initially pale beige, turning ochraceous brown with age, becoming concolourous to pileus, edge pale, fimbriate.Stipe 15-35(-40) × (2.5-)3-5 mm, dry, cylindrical, tapering upwards to subclavate; with age, brown to concolourous to pileus, usually bluish green at base but sometimes absent or very pale, apex ochraceous to brown; surface regularly squamulose to squarrose, covered with concolourous recurved scales, apex only flocculose.Context pale ochraceous to buff, hardly greenish to glaucous at the base of stipe, slightly reddening on the upper part of the stipe when cut.Odour sometimes faint, aromatic, fruity-acidic, sometimes with a scent of pelargonium or fish.Basidiospores (8.2-)9.0-10.9(-12.0)× (4.5-)5-6.1(-6.3)µm, Sp avg = 9.9 × 5. Distribution.The distribution of I. neohirsutum on the European continent is still unclear.It is very likely that some European records of I. calamistratum represent I. neohirsutum.To date, its presence has been confirmed in France, Norway, Sweden and Spain.However, according to the available distribution data and habitat preferences, it is likely to be widespread throughout the continent, thriving in humid forests in mainly temperate to mild climates of continental, Atlantic and hemiboreal type.It is unlikely that it will be found in colder climates of the northern boreal and alpine zones.There is only one sequence available matching I. neohirsutum, in the UNITE database, from Arendal, Norway, collected under Quercus and Corylus (UDB07673483/NOBAS 1849-16, as Inocybe calamistrata).
Ecology.It grows in both moist broadleaved forests of Fagaceae (Fagus and Quercus) and Betulaceae (Corylus) and mixed conifer-dominated forests, either in acidic or calcareous soils.
Etymology.From Greek néos, meaning new, and Latin hirsus, meaning hirsute, hairy, shaggy.Refers to a new or different interpretation of Inocybe hirsuta.
Additional specimens examined.FRANCE, Nouvelle-Aquitaine, Pyrénées-Atlantiques, Osse-en-Aspe, Forêt d'Issaux: 42 Notes.Agaricus hirsutus was described by Lasch [70] with a succinct description that could apply to both I. calamistratum and I. neohirsutum.The habitat is noted as "in fagetis humidis", a habitat that may support both species.Kuyper [4] considered Inocybe hirsuta to be a synonym of I. calamistrata, a treatment with which we agree, since it is impossible to separate the two species with the available data from the protologues.It is very likely that among the numerous records of I. calamistratum in Europe, some of them could correspond to I. neohirsutum.In our study, molecular analysis has confirmed the existence of two distinct species with rather similar morphological characters.
One of the macroscopic differences between the two species mostly lies in the size of the basidiomata.Inosperma calamistratum often produces larger basidiomes, with a normally long, fibrous and elastic stipe, whereas I. neohirsutum is smaller, with a more fragile stipe (Figure 9E-H).It is not improbable to assume that Lange's [71] interpretation of Inocybe calamistrata f. gracilis J.E. Lange (nom.inval., art.36.1) may correspond, at least in part, to I. neohirsutum.However, a studied collection (AH 58564) under Abies and Fagus from Aragón (Spain) showed a small size reminiscent of f. gracilis and is in molecular agreement with I. calamistratum.In these cases, to separate I. calamistratum and I. neohirsutum, it is necessary to analyse other morphological characters, such as the appearance of the pileus surface, the cheilocystidia, and the spore shape and size.
Inosperma neohirsutum is probably not an uncommon species from the humid, temperate forests of Europe, in both deciduous and coniferous forests.So far, it has been overlooked or probably misinterpreted as a smaller form of I. calamistratum.It has a very peculiar macroscopic character, namely, the squarrose aspect (reminiscent of Inocybe hystrix, for example) on the central disc of the pileus, which contrasts sharply with the more fibrillose to subsquamose margin, especially in adult specimens when the pileus is fully extended (Figures 5A and 9E-H).In I. calamistratum, the scales are very abundant, dense, sharp, thinner and mostly distributed over the whole surface of the pileus.The shape of the spores also differs between the two species, and although phaseoliform in both, this characteristic is somewhat less pronounced in I. neohirsutum (Figure 5B,F), where the Q avg is smaller (1.8 vs. 2.0).The trend in the morphology of the cheilocystidia of the two species also appears to be different, being narrower and subcylindrical in I. calamistratum.Because of its habitat, I. neohirsutum cannot be confused with other similar northern boreal and alpine species, such as I. gracilentum, I. subhirsutum and I. praetermissum.
In our phylogenetic analysis, I. neohirsutum appears to be closely related to I. subhirsutum, which has a lower Q avg of the spores, showing an ovoid to broadly ellipsoid outline, and to the North American species Inosperma apiosmotum (Grund & D.E.Stuntz) Matheny & Esteve-Rav., which is also small to medium in size and emits a typical odour of ripe pears.Grund and Stuntz [72] already noted in their observations its resemblance to Inocybe calamistrata and I. hirsuta.Inosperma apiosmotum and I. neohirsutum show similarities in the arrangement of scales on the pileus ([72], Figures 2 and 6) and in microscopic characters, such as the shape and size of spores and cheilocystidia.
Notes.Inosperma praetermissum is morphologically similar to I. calamistratum, I. gracilentum and I. subhirutum.After the revision of Karsten's type, Kuyper [4] considered I. praetermissum to be a synonym of I. calamistratum.However, the molecular study has allowed for a distinction between the two species.Inosperma praetermissum is relatively common in the hemiboreal, subalpine and alpine areas of the Northern Hemisphere and has probably been interpreted as a form or ecological variant of I. calamistratum.The latter prefers more temperate and very humid ecosystems, either continental or Atlantic, either mesophilic or montane, but the two co-occur in the hemiboreal zone in Fennoscandia.Apart from being genetically different, I. praetermissum can be separated, as it is smaller and more fragile in appearance than I. calamistratum.Inosperma praetermissum shows a clear tendency to have a pileus not as squarrose as that of I. calamistratum, with paler, woolly-fibrillose and looser scales that are not as prominent or as sharply defined, especially in the centre of the pileus (Figure 10A-C).Also often observed is the presence of a persistent ochraceous veil, resembling a fibrillose covering.In addition, the cheilocystidia are slightly longer than those of I. calamistratum, with a more elongated claviform outline, usually reaching 60 µm in length (Figure 6D).Care should be taken when observing the blue-greenish colour of the stipe and when perceiving the odour, as both can sometimes go unnoticed or blurred, especially if the specimens are old or soaked after heavy rain.Micromorphologically, the spores (Figure 6C,E) are somewhat similar in appearance to those of I. calamistratum, being subphaseoliform to phaseoliform in profile, although they are longer on average and often appear narrowly phaseoliform (12.2 × 5.3 µm vs. 10.4 × 5.1 µm; Q avg = 2.2 vs. 2.0).The odour of I. praetermissum was described by Karsten as unpleasant ("inamoenus") and strong ("gravis") and has been noticed in some specimens as smelling like fish brine.
Bon [5] mentioned the possible presence (most probably in the Alps) of Inocybe praetermissa (s.str.P. Karst.) at subalpine levels under conifers and Vaccinium bushes, to which he attributes a pileus surface not as hirsute as in I. calamistratum, an odour that sometimes eventually develops into that of I. cervicolor (earthy-mouldy), and elongated, narrow spores 12-14(-15) × 5-6(-7) µm.This interpretation agrees with the data obtained in the collections studied.
Inosperma gracilentum, which also occurs in alpine and boreal areas, can be confused with I. praetermissum, but the former is distinguished by its molecular characteristics, shorter cheilocystidia barely exceeding 40 µm in length, and the more ellipsoidal and somewhat broader spores (Sp avg 12.2 × 5.3 µm, Q avg = 2.2 vs. Sp avg 12.1 × 6.5 µm, Q avg = 1.8).
Inosperma subhirsutum collections growing in hemiboreal mixed Alnus forests and in subalpine Betula forests often have larger basidiomata than the average for the alpine zone, and they can then be confused in their macromorphology with I. pratermissum, but the two are clearly separated by spore morphology.
DNA extraction was successful in the holotype of Inocybe geraniodora var.gracilentum f. salicis-herbaceae, despite its poor condition.Based on the characters described in the protologue and on the study of the holotype (Figure 7), we consider it a synonym of I. praetermissum.The holotype of I. praetermissum shows slightly smaller and narrower spores (L/l avg 12.2 × 5.3 vs. 13.4 × 5.7; Q avg 2.2 vs. 2.3), although the other characters overlap or coincide in both.As in the case of I. geraniodora var.gracilenta f. salicis-herbaceae, the shapes of the spores of I. praetermissum are narrowly subphaseoliform in profile, and the cheilocystidia share similar dimensions and morphology.Finally, the phylogenetic study (ITS) indicates that both taxa are cospecific.The odour was also described as unpleasant and fishy.
zone, and they can then be confused in their macromorphology with I. pratermissum, but the two are clearly separated by spore morphology.
DNA extraction was successful in the holotype of Inocybe geraniodora var.gracilentum f. salicis-herbaceae, despite its poor condition.Based on the characters described in the protologue and on the study of the holotype (Figure 7), we consider it a synonym of I. praetermissum.The holotype of I. praetermissum shows slightly smaller and narrower spores (L/lavg 12.2 × 5.3 vs. 13.4 × 5.7; Qavg 2.2 vs. 2.3), although the other characters overlap or coincide in both.As in the case of I. geraniodora var.gracilenta f. salicis-herbaceae, the shapes of the spores of I. praetermissum are narrowly subphaseoliform in profile, and the cheilocystidia share similar dimensions and morphology.Finally, the phylogenetic study (ITS) indicates that both taxa are cospecific.The odour was also described as unpleasant and fishy.Distribution.Inosperma subhirsutum was first found in France in the alpine zone.It is more than likely that the species thrives at high altitudes in the Alps, as we have found by studying several samples from Italy.It is logical to assume its presence in other European countries with alpine ranges, such as Switzerland, Austria, etc., of which we have no records to date.Its presence in the Pyrenees is not known yet.According to the data collected by Jacobsson and Larsson [78], the species seems to be frequent and widely distributed in the boreal and alpine zones of Fennoscandia and Iceland.This is confirmed by several collections with sequences deposited in GenBank (AM882946 and AM882947) and the UNITE database (UDB001195 and UDB07673483).
Ecology.In Europe, it grows in alpine, subalpine and boreal areas, mainly on calcareous soils, but also sometimes on neutral or slightly acidic soils.It occurs mainly in communities of various shrubs and small Salicaceae, sometimes mixed with Betula nana or Bistorta vivipara.In calcareous soils, it is most often associated with Salix reticulata, S. retusa, S. glauca and Dryas octopetala.It can also be found with Salix herbacea on soils with a more acidic component or of a sandy nature due to soil washing.It is known to occur in the Alps in subalpine areas (e.g., in Lago Dobbiaco, Italy, EB 20140807), close to Salix near watercourses in coniferous forests (Picea).In boreal areas, it can also be found in coniferous vegetation, associated with Salix, or in mixed forests with Populus tremula, Alnus incana and Betula pubescens (GB 0243043).The ectomycorrhizal relationship of I. subhirsutum with Salicaceae especially seems obvious, as well as its localisation in hemiboreal, subalpine and alpine zones.
Etymology.From the Latin sub-, meaning under, beneath, behind and near, and hirsus (variant of hirtus), meaning shaggy, rough, hairy, referring to the appearance of the pileus.
Additional specimens examined.FINLAND, Ostrobottnia ultima, Rovaniemi, Kylmäoja: moist area with Populus tremula, Betula pubescens and Alnus incana, 200 m alt., 3  Notes.Inosperma subhirsutum is another hemiboreal to alpine species in the Calamistratum group.From its morphological and organoleptic characteristics, it seems to show some similarities with the species of the Geraniodorum group in terms of the appearance and shape of the pileus, its surfaces, and its odour reminiscent of pelargonium [77].Its spores show a certain variability, even in the same collection, and are often flattened and sometimes slightly concave to subphaseoliform in profile view (Figure 8C,E).In frontal view, the spores are ovo-ellipsoid to ellipsoid and broader.According to our observations, the greenish-blue colour at the base of the stipe noted by Kühner in his original diagnosis may be variable, and some collections show a greenish grey to dark dirty-grey at the base, but this colour may be completely absent in some collections (EB 2014080711).Also noteworthy is pelargonium-like odour in young specimens, which may become fishy later (according to Kühner, the odour is "reminiscent of herring").
Characteristic of I. subhirsutum are the pileus and stipe coverings (Figure 10D,E), which are usually woolly-fibrillose ("mallocyboid").However, some collections show a more hirsute pileus surface (e.g., EL 11-19, Figure 10F).The stipe is similar in appearance to the pileus, also woolly-fibrillose, and never hirsute or squarrose.We have observed a variable tendency to reddening of the flesh and, in some collections of young specimens, the presence of a yellowish tinge in the lamellae.
Kühner [77] provisionally named this species Inocybe calamistrata var.latispora, because the spores have a distinct ovoid-ellipsoid outline in frontal view, in contrast to I. calamistratum and other similar species, where narrower spores with subphaseoliform to phaseoliform outlines predominate.Only I. gracilentum can show spores of similar width to I. subhirsutum, but the Q avg is higher (1.8-2.0), and therefore their appearance is more elongated.Kühner's paper was published after the validation of the holotype, due to a delay in publication.
The numerous collections studied, especially those from Fennoscandia, where it seems to be common, indicate that the spore morphology of I. subhirsutum may show some variation in width and appearance.The holotype collection shows a clear dominance of broadly ellipsoidal to ovo-ellipsoidal spores in frontal view, but this feature is variable even within the same collection.Kühner [77] reported spore dimensions of "9-10.6-13.5-14.7 × 6.2-6.7-8.2-9µm, Q = 1.4-1.7",which is in reasonable agreement with our examination of the holotype.The holotype was originally collected in an alpine zone under Salix reticulata on calcareous soil ("in calcareo solo", according to Kühner), but we have also studied genetically matching samples from more acidic soils (probably washed) with Salix herbacea.These latter may also show some variability in spore size and shape, also including spores that are slightly narrower and more ellipsoidal than those reported for the holotype.Unfortunately, we were only able to observe a few cheilocystidia in Kühner's collection, as the lamellar edge was quite collapsed, and the dimensions given here are only approximate.Very interesting are the data reported by Kuyper [79] from a collection in Jämtland (Sweden) under Salix retusa in the boreal zone; although he called it I. calamistrata, considering it and I. subhirsuta as synonyms, it seems to correspond to the latter because of its wider spores of 6-6.5 µm and its habitat.Phylogenetic studies support the separation of the two species at the specific level.
As can be observed from the phylogenetic tree (Figure 1), there is a rather large amount of genetic variation within I. subhirsutum, and we can genetically regard it as a species complex.There is a tendency to separate the strict Arctic-alpine specimens associated with dwarf Salix and Dryas and those from the boreal areas associated with Populus tremula, Alnus, Betula pubescens and mixed Pinus-Betula habitats.However, more data are needed to confirm this hypothesis to determine whether genetic data can be correlated with the observed morphological variation in, e.g., spore morphology and habitats.
Ecology.Inosperma geraniodorum inhabits alpine and northern boreal ecosystems on calcareous soils, associated with various dwarf willows (Salix reticulata, S. retusa, etc.) and Dryas octopetala, and most probably with Bistorta vivipara.It can also develop in subalpine ecosystems at the upper limit of coniferous forests, between 1750 and 2000 m alt.[85].The lectotype was collected in the subalpine level close to Alnus alnobetula, with which it can probably establish ectomycorrhizae.Description.Favre [69], Kuyper [4], Senn-Irlet [80], Bizio [81], Bon [65], Breitenbach and Kränzlin [57].Etymology.From the Latin Geranium, the plant which is commonly called pelargonium or geranium, and odor = smell, because its smell is reminiscent of this plant.Notes.Inosperma geraniodorum can be recognised by the absence of a blue-greenish colour of the stipe, the slender habit ("mycenoid" type, according to Vellinga [25]), usually with a paraboloid to campanulate, often subumbonate pileus, the dark chocolate-brown colour of the basidiomata, the fibrillose to squamulose surface of the pileus (Figure 15C,D), and the large ellipsoid spores (Figure 11E,F).In young specimens, the typical smell of pelargonium is perceptible, although in some cases a fishy or cucumber component is present, especially in mature specimens.Similar in odour to I. geraniodorum is I. veliferum, which is slightly smaller and has a convex, not or hardly umbonate pileus, which is finely felted-fibrillose and initially covered with a persistent whitish veil.Inosperma geminum, with an odour and habitat similar to those of pelargonium, is another small and reddish-brown species, but it does not have a persistent veil and differs from I. geraniodorum and I. veliferum in its slightly smaller and narrower spores, with marked phaseoliform to naviculiform tendency in profile, and shorter cheilocystidia on average.
According to the data obtained from our phylogenetic analysis, the species most closely related to I. geraniodorum is I. turietoense.Both have a similar habit, with a slender stipe much longer than the diameter of the pileus, a brown to brownish-red colour, a poorly developed or absent veil, a pileus with a fibrillose scaly surface, and large spores.However, they differ in their ecological preferences, as I. turietoense is a nemoral species in mountainous areas, not reaching subalpine or alpine altitudes, it is larger in size, and the pileus is decorated with a characteristic appressed scaly, tabby ornamentation, which contrasts strongly with the background due to its darker colour.Inosperma turietoense does not have the characteristic pelargonium odour of I. geraniodorum.
Favre [69] first described I. geraniodorum based on several collections without designating a holotype (citing several syntypes).He also mentioned its occurrence in the upper subalpine zones of the areas visited [85].The collection chosen by Kuyper [4] as the lectotype has been successfully sequenced and allows us to clarify its taxonomic position.In the herbarium of J. Favre, deposited in G, there are about twenty collections identified by the Swiss mycologist as Inocybe geraniodora.Apart from the lectotype, molecular data have not yet been obtained for any of them, so it is quite likely that some may correspond to other close or similar species (such as I. veliferum).
Favre's original description of I. geraniodorum was based on the syntypes, and this fact can be confirmed by the various collections mentioned and drawn by him in the protologue.The study of the lectotype has shown spores slightly shorter than those given by Favre [14-18(-19.5)µm], but it cannot be ruled out that some of these collections have bisporic basidia (a common occurrence in high mountain collections), and consequently the basidiospores show some variability in length.However, we did not observe bisporic basidia in the lectotype, as the hymenial elements were collapsed.This is quite common in Inosperma specimens.In Favre's iconography ( [69]: 83, Figure 67) the macromorphological variability between different collections and their microscopic characteristics are clearly shown.
Inocybe geraniodora var.gracilenta was also introduced by Favre [69] but invalidly published.It was considered a variant of I. geraniodora in the alpine zone, characterised by its very small size, smaller spores and shorter cheilocystidia, 32-50 × 9-13 µm.The only existing collection in G was successfully sequenced, and the ITS was obtained.It corresponds to a species belonging to the Calamistratum group and is presented in this paper as a new species (see I. gracilentum).Favre [69] does not mention the odour of this variant, but, presumably because of its name, it should be like that of I. geraniodorum and therefore have a pelargonium component.Also, in Favre's iconography ( [69], pl VI, Figure 5), the specimens do not show a blue-greenish tinge at the base of the stipe, which could lead to misinterpretation (Favre's iconography could bring to mind specimens of I. geraniodorum).
Distribution.So far known from the alpine zone in Sweden and Norway.No additional sequence matching data were available in GenBank, but there is one specimen in the UNITE database that originates from Norway (UDB07673341|NOBAS 1542-15).
Ecology.It seems to be restricted to herb-rich alpine ecosystems on calcareous ground, associated with Dryas octopetala and Salix reticulata.
Etymology.Refers to the Latin word geminum, meaning twin, double, pair, resembling or similar to, because of its similarity to I. veliferum and I. geraniodorum.Notes.Inosperma geminum is very similar to both I. geraniodorum and I. veliferum.It is a small species characterised by an obtusely conical to plano-convex ochraceous-brown to reddish-brown pileus, fibrillose at the margin and distinctly squamulose at the centre of the pileus, with an ochraceous-brown stipe (Figures 12A and 15A,B).It has a distinct odour of pelargonium and fish.It is phylogenetically most closely related to I. veliferum, they have similar habitat and their geographic distributions and ecologies Inosperma geminum seems to be rare and less common than I. geraniodorum and has on average smaller basidiomata and a smaller pileus diameter than the latter.The two can also be separated in terms of micromorphology, as I. geminum has, on average, slightly shorter spores (Figure 12B,F) and a larger Qavg = 1.9 vs. 1.6.Notes.Inosperma turietoense has certain morphological similarities and is phylogenetically closely related to I. geraniodorum.The basidiomes are of medium size and slender appearance, but larger than those of I. geraniodorum (Figures 13A and 15G,H).The ellipsoidal spores (Figure 13B,H) are similar in both, although on average slightly narrower in I. turietoense (13.7 × 7.9 µm vs. 12.0 × 6.8 µm).It also differs in several notable diagnostic characters: the tabby scaly appearance of the pileus centre, with darker adpressed and delicate scales, the different odour without traces of pelargonium, and a more continental, temperate, montane habitat.In the collections studied, I. turietoense has a typically atten-uated stipe towards the base, and the reddening of the flesh surface of the stipe is noticeable.Collections made in situ have led us to make an approximate identification with a member of the Cervicolor group, whose species are phylogenetically distant and show some differences in pileus appearance, but it gives an idea of the first impression of the new species.Inosperma veliferum and I. geminum have smaller basidiomata with a distinct whitish velipellis, at least when young, a pure pelargonium smell in young basidiomes, and boreal-alpine distribution.show some differences in pileus appearance, but it gives an idea of the first impression of the new species.Inosperma veliferum and I. geminum have smaller basidiomata with a distinct whitish velipellis, at least when young, a pure pelargonium smell in young basidiomes, and boreal-alpine distribution.(including the holotype) show broadly ellipsoidal spores and more fibrillose-woolly to surfaces.Inosperma geraniodora var.velifera was described by Kühner [77] from the French Alps.Bon [65] raised it to the rank of a separate species because of the presence of the characteristic veil and the lower Q of the spores.It is recognisable by its small size and the more obtuse and convex appearance of the pileus, which is not or hardly umbonate and never has a squamulose surface, but is smooth to fibrillose (Figures 14A and 15E,F).A good diagnostic feature is the presence of an abundant whitish veil, especially in young or unwashed specimens, which totally or partially camouflages the reddish-brown colour of the pileus.In I. geraniodorum and I. geminum, the veil may be present on the pileus disc in young stages, but in no case is it so abundant or developed, and both have a subsquamose pileus centre.Because of its small size, I. veliferum can be confused with I. geminum, the species to which it appears to be the most closely related phylogenetically.The pileus of the latter is sometimes more campanulate and subumbonate and is distinctly squamulose at the centre, and its spores are narrower (13.2 × 8.0 µm vs. 12.5 × 6.7 µm), with a marked subphaseoliform to naviculiform tendency in profile.So far, Inosperma geminum has been found exclusively in the alpine zone of the Scandinavian mountains, whereas I. veliferum seems to be restricted to the alpine areas of central Europe and the Pyrenees.However, I. geraniodorum is widespread in both alpine and boreal regions and can also be found at subalpine altitudes between 1800 and 2000 m [85].Comparative studies of the size and shape of spores and cystidia of the samples of I. geraniodorum and I. veliferum studied have not shown any remarkable or distinct microscopic differences between the two for diagnostic use.Both species have similar average dimensions in spore size, as well as size and shape of the cystidia.The macroscopic appearance of I. geraniodorum is slightly different, producing darker and generally larger basidiomes, often with a squamulose conical to subumbonate pileus, and the veil, if present, is more diffuse and transient.

Discussion
Organoleptic characters have historically had great importance in the recognition of Inosperma species.Contrary to what has been assumed in the past, members of Inosperma can be distinguished based on their morphological and ecological characteristics, and their identification is not so dependent on the interpretation of organoleptic characters.In the case of Inosperma, it is relatively common to collect specimens with certain morphological characteristics that are difficult to interpret, mostly due to the influence of environmental factors and the ageing of the basidiomes.These factors can modify the external appearance of certain characters (colour, size, appearance of the basidiomata surfaces, or redness), as well as the perceived odour.For Inosperma, it is particularly advisable to collect specimens in good and fresh condition and at different stages of development, which makes it easier to interpret these changes.In some collections, the bluish-green colour of the stipe base, so characteristic of the Calamistratum group, can be diminished or even disappear; in the same way, the reddening and odour of the specimens can undergo significant changes within a few hours.These changes greatly complicate the species determination if they are overestimated.
Our phylogenetic analyses inferred from the ITS-LSU-RPB1-RPB2 regions recovered nine clades containing samples obtained from European material and highly congruent with respect to morphological characters.All clades but one received phylogenetic support in at least one of the analyses.The Inosperma subhirsutum clade, however, did not receive support.The high sequence divergence within this clade and the high amount of missing data may have contributed to the lack of phylogenetic confidence.Our analyses support a high rate of continental endemicity within the Calamistratum group, as all the species seem to be restricted to a single continent, with the only-judging from the data available to date-exception of I. praetermissum, which appears to be present in North America (PBM 1105, WTU) as well.The fact that the backbone of the tree is not supported may be due to a high amount of missing data.
Our study demonstrates that the Calamistrata and Geraniodora groups are more diverse than previously considered in Europe and that several species have been subsumed under the names I. calamistratum and I. geraniodorum.The nine species present in Europe can be distinguished generally through morphological characters, at least when good, fresh, not weathered material is available.The main taxonomic informative characters that allow for species recognition are pileus and stipe scaliness, spore shape, and cystidial shape and size.Some species show a rather high sequence divergence in the ITS region (I.subhirsutum and I. praetermissum) and may comprise more than one evolutionary lineage.Nevertheless, obtaining a more complete dataset of protein-marker regions would be necessary to further test this possibility.We hope that this study contributes to an increased interest in and provides an updated identification guide for the Calamistratum and Geraniodorum groups.

Figure 1 .
Figure 1.Most-probable ML tree of the ITS, LSU, RPB1 and RPB2 sequences of the Inosperma calamistratum and I. geraniodorum groups.Bootstrap ML values/posterior probabilities from Bayesian analysis are shown around the branches.Thick branches indicate nodes with phylogenetic support in at least one of the analyses (bootstrap values ≥ 70% and posterior probability ≥ 0.95).Sequences of Mallocybe tomentella, M. terrigena and Auritella fulvella were used to root the tree.The country of origin of each collection is abbreviated by ISO Alpha-3 codes.Specimens sequenced in this work are marked in bold.

Figure 1 .
Figure 1.Most-probable ML tree of the ITS, LSU, RPB1 and RPB2 sequences of the Inosperma calamistratum and I. geraniodorum groups.Bootstrap ML values/posterior probabilities from Bayesian analysis are shown around the branches.Thick branches indicate nodes with phylogenetic support in at least one of the analyses (bootstrap values ≥ 70% and posterior probability ≥ 0.95).Sequences of Mallocybe tomentella, M. terrigena and Auritella fulvella were used to root the tree.The country of origin of each collection is abbreviated by ISO Alpha-3 codes.Specimens sequenced in this work are marked in bold.

Table 1 .
List of collections used in the molecular analyses.The sequences generated in this study are in bold.
Inosperma geminum differs from other morphologically similar species, such as I. geraniodorum and I. veliferum, by having smaller basidiomata and narrower spores that are adaxially plane to slightly concave or subphaseoliform, often with a navicular appearance in lateral view.They differ in ITS sequence data and are phylogenetically distinct.