Mycological Progress

, Volume 9, Issue 4, pp 575–583

Xeromphalina setulipes (hygrophoroid clade, Agaricales), a new Mediterranean species

Authors

    • Dpto. de Biología Vegetal (Botánica), Fac. BiologíaUniversidad de Alcalá de Henares
  • Gabriel Moreno
    • Dpto. de Biología Vegetal (Botánica), Fac. BiologíaUniversidad de Alcalá de Henares
  • Jose Luis Manjón
    • Dpto. de Biología Vegetal (Botánica), Fac. BiologíaUniversidad de Alcalá de Henares
  • Pablo Alvarado
    • Dpto. de Biología Vegetal (Botánica), Fac. BiologíaUniversidad de Alcalá de Henares
Original article

DOI: 10.1007/s11557-010-0665-6

Cite this article as:
Esteve-Raventós, F., Moreno, G., Manjón, J.L. et al. Mycol Progress (2010) 9: 575. doi:10.1007/s11557-010-0665-6

Abstract

A new Xeromphalina species from Mediterranean evergreen forests of the southern part of the Iberian Peninsula is described. It is characterized by its habitat on soil, arcuate-decurrent lamellae, trama hyphae which turn distinctly orange-brown to red-brown in KOH solution, thick-walled caulocystidia with an attenuate apex reminding setulae, and versiform to irregularly cylindrical cheilocystidia, which are conspicuously branched forming coralloid excrescences. LM microphotographs illustrate its diagnostic features. Additionally, two nuclear ribosomal DNA regions from this new taxon were sequenced and compared with homologue sequences from existing species in the genus Xeromphalina, supporting its recognition as a new species.

Keywords

BasidiomycetesTricholomatalesMediterranean mycobiotaTaxonomyNew species

Introduction

During field work carried during the autumn of 2005 in the southern part of the Iberian Peninsula, we discovered a ΄xeromphalinoid΄ agaric which was later determined as an unknown species of the genus Xeromphalina; it is presented here as X. setulipes, because of its peculiar protruding caulocystidia with a shape reminiscent of thick-walled setulae, similar to those present in many species of the genera Inonotus and Phellinus; this particular feature is only known in a few species of this genus. In addition, X. setulipes shows trama hyphae which turn dark orange-brown to red-brown in KOH solutions, and this combination of characters makes it very distinct.

About eight species (and some varieties) of Xeromphalina are known from European countries (Antonín and Noordeloos 2004), but from these, only two have been unambiguously and regularly recorded from Europe (X. campanella (Batsch) Maire and X. cauticinalis (With.) Kühner & Maire (= X. fellea Maire & Malençon). A similar situation has occurred in the Iberian Peninsula, where a third species, known as X. junipericola G. Moreno & Heykoop, was described only a few years ago by Moreno and Heykoop (1996), growing on Juniperus thurifera rotten wood and showing a peculiar pigment composition. Finally, a fourth species, X. minutissima, was invalidly published by Esteve-Raventós (1995), and because of the very scanty material (only one tiny specimen), the author considered that more collections were needed to proceed to its validation.

In spite of the few known taxa, Xeromphalina is, however, a rather well-studied genus in Europe, where it has been the object of some monographic continental and local contributions (Klán 1984; Gulden 1992; Watling and Turnbull 1998; Bon 1999; Ludwig 2001; Antonín and Noordeloos 2004; Noordeloos 2008). Also, monographic studies have been made by Smith (1953), Miller (1968), and Redhead (1988) on North American species (the last also dealing with the northern Eurasian taxa), and some additions were also contributed from the South American (Singer 1965; Redhead and Halling 1987) and Asian continents (Horak 1979).

At the present time, following the phylogenetic study of Matheny et al. (2007), Xeromphalina is considered a member of the “hygrophoroid clade”, close to the gilled genera Sarcomyxa P. Karst. and Phyllotopsis E.-J. Gilbert & Donk ex Singer, as well as the, morphologically distinct, members of the families Pterulaceae Corner and Typhulaceae Jülich; previously, Moncalvo et al. (2002), had recognized a distinct clade ΄xeromphalinoid΄ (no. 69) among the core of the white-spored euagarics. Outdated classifications based on morphological characters situated Xeromphalina in the Tricholomataceae (Kirk et al. 2001, 2008) and Mycenaceae (according to the Index Fungorum) and Xerulaceae Jülich (Redhead 1987). Prior to these, both Singer (1986) and Kühner (1980) included this genus in the Tricholomataceae R. Heim ex Pouzar, in the tribes Myceneae and Marasmieae, respectively. Singer’s point of view was followed by Antonín and Noordeloos (2004) in their monograph on European taxa.

Materials and methods

The only collection consists of four specimens, all growing on soil among vegetal debris in a Mediterranean Quercus suber forest. The material, though scanty, is preserved in excellent condition, and is fully mature and well sporulated. The type collection has been deposited at AH (Departamento de Biología Vegetal, Universidad de Alcalá, Spain), with color photographs of the basidiomes taken in the field.

Microscopical slides of dried material were prepared with 5–10% NH4OH, 5–10% KOH and Melzer. Digital photographs for the plates were taken with a Nikon camera, model DS-5 M, mounted to a binocular Nikon Eclipse 80i microscope. Spore measurements are quoted according to Heinemann and Rammeloo (1985), where Q=L/l means the quotient between the averages of length (L) and breadth (l), established with a minimum of 20 spores measured. Colors of fresh and dried basidiomes were compared with reference colors in Munsell (1994). Terminology of microscopical elements, especially cystidia (for example, circumcystidia is referred to those pileocystidia largely confined to a band around the pileus margin), has been mainly adopted from Redhead (1988) and also from Antonín and Noordeloos (2004).

Total DNA from Xeromphalina setulipes holotypus (AH36724) and also from several European representatives of the genus Xeromphalina deposited at AH (Table 1), was extracted by means of the MasterPureTM Plant Leaf DNA Purification Kit (Epicentre Biotechnologies, Madison, US) following the manufacturer’s instructions: 1 μl of resuspended DNA was added to each 50 μl PCR mixture with the following composition: 1u EcoTaq DNA polymerase with 1× EcoTaq Buffer (Ecogene), MgCl2 2 mM, and 0.2 mM of each of the DNTPs. The primers LR1 (5′-GCA TAT CAA TAA GCG GAG GA-3′, Van Tuinen et al. 1998) and LR7 (5′-TAC TAC CAC CAA GAT CT-3′, Vilgalys and Hester 1990) targeting the 5′ end of the 28S nrLSU, and primers NSI1 (5′-GAT TGA ATG GCT TAG TGA GG-3′) and NLB4 (5′-GGA TTC TCA CCC TCT ATG AC-3′) from Martin and Rygiewicz (2005) targeting the nuclear ribosomal internal transcribed spacer (nrITS), were added at 0.5 μM each in independent PCR reactions. PCR consisted of a hot start at 95°C for 5 min, five cycles at 94°C, 50°C, and 72°C (45, 30, and 45 s, respectively), followed by 30 cycles at 94°C, 54°C, and 72°C (45, 30, and 45 s, respectively) and a final 72°C step for 10 min. PCR products were checked in 1% agarose gels prior to purification with UltraClean PCR Clean-up DNA purification kit (MoBio Laboratories, Carlsbad CA). The same PCR primers were used for sequencing. Chromatograms and sequences were visually compared in MEGA4 in order to detect compromised data.
Table 1

DNA data from the genera Xeromphalina, Heimiomyces, and Sarcomyxa

Taxon

Reference

nLSU

ITS

Xeromphalina

Xeromphalina cauticinalis AH37873

This work

GU320011

GU320004

Xeromphalina cauticinalis AH37874

This work

GU320005

Xeromphalina aff. parvibulbosa TENN61775

Hughes et al. (2009)

FJ596890

Xeromphalina aff. parvibulbosa TENN61775

Hughes et al. (2009)

FJ596889

Xeromphalina cornui TENN6397

Moncalvo et al. 2002

AF261463

Xeromphalina campanelloides TENN6368

Moncalvo et al. 2002

AF261462

Xeromphalina setulipes AH36724

This work

GQ890700

GQ890701

Xeromphalina campanella TENN7250

Moncalvo et al. 2002

AF261469

Xeromphalina campanella AFTOL-ID 1524

Matheny et al. 2007

DQ470826

DQ494702

Xeromphalina campanella 3922

This work

GU320009

GU320006

Xeromphalina campanella

Walther et al. 2005

AY207312

Xeromphalina fraxinophila TENN6398

Moncalvo et al. 2002

AF261464

Xeromphalina austroandina TENN7392

Moncalvo et al. 2002

AF261466

Xeromphalina helbergerii TENN6255

Moncalvo et al. 2002

AF261465

Xeromphalina junipericola AH19695

This work

GU320010

GU320007

Xeromphalina junipericola AH19696

This work

GU320012

GU320008

Xeromphalina kauffmanii TENN6906

Moncalvo et al. 2002

AF261467

Heimiomyces

Heimiomyces tenuipes TENN6908

Moncalvo et al. 2002

AF261471

Heimiomyces fulvipes TENN5864

Moncalvo et al. 2002

AF261470

Sarcomyxa

Sarcomyxa serotina I354

Arhipova et al., unpub.

GU062305

Sarcomyxa serotina UASWS0313

Belbahri et al., unpub.

EF174452

Sarcomyxa serotina AFTOL-ID 536

Matheny et al. 2007

AY691887

DQ494695

Sarcomyxa serotina ACCC 50309

Gao et al., unp.

EU365678

Sarcomyxa serotina TM03_367

Porter et al. 2008

EU522798

Sarcomyxa serotina

Garnica et al. 2007

DQ071731

Phylogenetic analyses were performed using about 800 bp of nrLSU 5′ end and 650 bp of the ITS1-5.8S-ITS2 region. Homologue sequences of both genes from species in the genera Xeromphalina, Heimiomyces, and Sarcomyxa deposited at GenBank (Table 1) were aligned in MEGA4 using the ClustalW application. Most of the sequences gathered from GenBank were properly identified by specialists before sequencing (Johnson and Petersen 1997). The sequences were used in this work as they were the only available for molecular comparison of the new species. No position was considered ambiguous enough to be deleted in the final alignments. A neighbor-joining phylogenetic tree was constructed for each gene (5,000 bootstrap replicates, maximum composite likelihood model, pairwise deletion of gaps). Additionally, alignments were uploaded in PAUP* 4.0b10 (Swofford 2001) and a bootstrap search under the maximum parsimony criterion was performed. A thousand bootstrap replicates were executed using the tree-bisection-reconnection swapping algorithm, 50 random sequence additions in each replicate, and the MulTrees option not in effect. Finally, a maximum likelihood analysis of each alignment was performed in MrBayes 3.1 (Ronquist, Huelsenbeck and van der Mark) under the model specified by a previous MrModeltest (Nylander 2004) run in PAUP* 4.0b10. The best models for ITS and nLSU alignments were HKY+Γ and GTR+Γ, respectively. Maximum likelihood analyses employed 4 metropolis-coupled Monte Carlo Markov Chains (MCMC) with the temperature of the chains set to 0.2. Data sampling was done once for each 100 generations. The analysis was run until convergence parameters were met in two simultaneous runs, after 400,000 and 900,000 generations for ITS and nLSU alignments respectively. A full search for best-scoring ML trees was also performed in RAxML (Stamatakis 2006) using the standard search algorithm, and 1,000 bootstrap replications.

Results

Phylogenetic analyses

BLAST searches of the sequences from Xeromphalina setulipes in NCBI web service resulted in more than 90% identity with species in the genus Xeromphalina in more than 75% (ITS) or 60% (nLSU) of the sequence length. The final alignment of the nLSU and ITS regions included 45 and 187 parsimony-informative sites, respectively. Both nLSU and ITS inference supported the differentiation of, at least, three clades within the genus Xeromphalina. Xeromphalina setulipes grouped with X. fraxinophila, X. cornui, X. campanelloides and X. cauticinalis in one of them. ITS inference proved X. setulipes and X. cauticinalis to be different species. Samples of X. cauticinalis from the Iberian Peninsula seemed also somewhat different from those of the North American X. aff. parvibulbosa. Xeromphalina aff. parvibulbosa was related to X. cauticinalis on the basis of neighbor-joining and maximum parsimony analyses, while maximum likelihood supported a closer relationship between X. setulipes and X.aff. parvibulbosa (data not shown). Xeromphalina junipericola was here sequenced for the first time, and seemed to be unrelated to the X. cauticinalis group on the basis of ITS data, while nLSU inference placed it in close relationship with X. helbergerii. This should be further confirmed by ITS analysis of the latter due to the relatively scarce number of informative sites in the nLSU region.

Taxonomy

Xeromphalina setulipes Esteve-Rav. & G. Moreno, sp. nov.—MycoBank MBS 16618; Figs. 1 and 2
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Fig. 1

Xeromphalina setulipes holotype AH 36274. Basidiomes. Scale bar 10 mm

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Fig. 2

Xeromphalina setulipes holotype AH 36274. a Detail of the stipe apex, pileus margin and lamellae insertion. b Floccose-velutinous stipe due to the presence of setuloid caulocystidia. c Mycelial tomentum at the stipe base. d Pileipellis constituted by cylindrical incrusted hyphae with yellowish-brown pigment observed in phase-contrast. e The same in Congo red. f–g Basidia and basidioles. h–i Clamp-connections. j Amyloid basidiospores. k–l Setula-like caulocystidia showing thick walls. m–o Coralloid cheilocystidia. Scale bars a 3 mm, b,c 1 mm, d–o 10 µm

Etymology. From latin ΄setula΄ = stiff hair, and ΄pes΄ = foot, owing to the stipe covered with setose hairs.

Pileus 8–15 mm latus, convexus vel plano-convexus, haud striatus, rufo-brunneus vel hepaticus, glaber vel rugulosus, margine pallescente, leviter sericeo. Lamellae subconfertae, arcuato-decurrentes, brunneolae. Stipes 30–45 × 1–2 mm, cylindraceus, purpureo-brunneus vel subniger, minute pubescens, corneus, basi tomentosa, tomento cinnamomeo. Caro tenuis, cartilaginea, brunneola, odore nullo, sapore mitis, non acerbo.

Sporae Q= L × l: 5.0–6.1–7.3 × 2.9–3.3–3.7 µm, Qm: 1.6–1.87–2.1 (n = 21), ellipsoideae vel subcylindricae, leves, hyalinae, amyloideae. Basidia 21–26(−30) × 4.5–5.5 µm, clavata, tetraspora; sterigmata usque ad 3 µm longa. Cheilocystidia 30–80 × 3–7 µm, hyalina, coralloideo-ramosa. Caulocystidia 30–60 × 5–10 µm, fusiformia vel setuliformia, crassitunicata, luteo-brunnea. Pileipellis incrustata, rubrobrunnea in KOH. Hyphae fibulatae. Ad terram in silvis mediterraneis frondosis (Quercus, Cistus). In Hispania. Holotypus AH 36274.

Basidiomes epigeous, gregarious. Pileus 8–15 mm in diam., convex to plano-convex, with depressed centre, remaining so at maturity; not or scarcely hygrophanous, not translucently striate at margin, dark red-brown, hepatic-brown to chocolate-brown (2.5 YR 3/4–3/6; 10 R 3/3–3/6), somewhat pallescent on drying to tobacco-brown (2.5 YR 4/3–4/6; 5 YR 4/4–4/6), especially towards the edge; surface glabrous when young, becoming rugose to rugulose with age, slightly pallescent and becoming somewhat sericeous towards margin when dry; margin inflexed, typically undulate to crenate. Lamellae subdistant (L = 15–18), with lamellulae (l = 1–2), distinctly arcuate-decurrent, up to 2 mm broad, tobacco-brown (5 YR 4/4–4/6) when young and remaining so at maturity, at times bifurcate, with paler, whitish and crenulate edge. Stipe 30–45 × 1–2 mm, cylindrical, somewhat enlarged at extreme base, stiff or cartilagineous, uniformly dark purplish-brown (2.5 YR 3/2–3/4 or 2.5/1–2.5/4) to nearly blackish-brown; apparently smooth, but finely pubescent-floccose under the lens (owing to the setulose brownish caulocystidia); basal tomentum well developed, amber to ΄ozonium-like΄ colored (5 YR 5/6–5/8). Context cartilagineous, concolorous with the surface; smell indistinct, taste not bitter. Rhizomorphs present, chestnut-brownish.

Spores Q = L × l: 5–6.1–7.3 × 2.9–3.3–3.7 µm, Qm: 1.6–1.87–2.1 (n = 21), amyloid, ellipsoid to subcylindrical, thin-walled, smooth. Basidia 21–26(−30) × 4.5–5.5 µm, 4-spored (rarely 2-spored), narrowly clavate to subcylindrical, with sterigmata up to 3 µm long. Lamellar edge heterogeneous, composed by numerous cheilocystidia mixed with some scattered basidia. Cheilocystidia abundant, 30–80 × 3–7 µm, sinuose to irregularly cylindrical, conspicuously branched forming dense ΄coralloid΄ excrescences (Mycena-like) 3–10 µm long, thin-walled, hyaline. Hymenophoral trama made up of cylindrical, parallel, thin-to slightly thick-walled, 4–8 µm wide hyphae, with walls smooth or slightly encrusted with brownish pigment which turns orange-brown in KOH. Pileipellis a not or hardly gelatinized cutis, constituting of interwoven to more or less radially arranged, slightly thick-walled, cylindrical, 5–10 µm wide hyphae, with yellowish-brown parietal pigment which turns reddish-brown in KOH. Subpileipellis made up of parallel, 4–8 µm wide hyphae, with finely encrusting yellowish-brown pigment, which turns orange-brown with KOH. Circumcystidia numerous, similar to cheilocystidia, showing numerous lateral branches, ΄rod-like΄ projections or diverticulae, forming coralloid masses, usually thick-walled. Stipitipellis a cutis of parallel, cylindrical, thick-walled hyphae, with dark red-brown parietal pigment which turns darker in KOH. Caulocystidia very numerous, of similar shape along the entire stipe, strongly projecting, 30–60 × 5–10 µm, fusoid-ventricose, often sinuose or curved, exceptionally simply branched but never lobed at distal ends, with attenuated obtuse apex (΄setula-like΄), distinctly thick-walled, walls up to 2.5 µm wide, brown-yellowish pigmented. Clamp-connections present.

Substratum. On acid soil, among vegetal debris in a mixed Quercus suber/Q. faginea forest with Cistus ladanifer, Erica sp. and Juniperus cf. oxycedrus undergrowth.

Distribution Only known from the type locality, in Ciudad Real province, Spain.

Specimens examined. SPAIN, Ciudad Real Province, Fuencaliente, camino del Robledo de las Hoyas, 30SUH8553, 770 m asl, on soil among vegetal debris near Cistus, Erica and Juniperus shrub, in a Mediterranean mixed Quercus suber/Q. faginea forest, in acid soil, 17 Nov. 2005, F.D. Calonge, F. Prieto, M.A. González & F. Esteve Raventós, holotype Herb. AH 36274.

Discussion

Xeromphalina setulipes shows a distinct color change in the pileipellis in KOH solutions, turning dark reddish-brown; this color change of the tissues has been emphasized previously by Smith (1953), Redhead (1988), and Antonín and Noordeloos (2004) to separate some groups of species. Based on this character, Smith (1953) proposed section Mutabiles, which includes X. campanelloides Redhead, X. cauticinalis, X. cirris Redhead, X. cornui (Quél.) J. Favre, X. fraxinophila A.H. Sm., X. parvibulbosa (Kauffman & A.H. Sm.) Redhead and X. setulipes. Also in this section, the presence of rhizomorphs and irregular and branched circumcystidia are characteristic.

Morphologically, X. setulipes is similar in habit to the circumboreal X. cauticinalis; both species also show a characteristic amber tomentum at the stipe base, and also grow on soil, not directly on stumps or rotten wood; X. cauticinalis also shows some fusiform caulocystidia which remind of those of X. setulipes, but these are mixed with typical coralloid or lobed ones, which we have not observed in the new species in any part of the stipe; moreover, they also differ in many characters, such as the overall colors, and the yellow paler stipe apex in X. cauticinalis, very different to the uniformly dark brown-chestnut to blackish stipe of X. setulipes. Lastly, both species also differ in taste, which is very bitter in X. cauticinalis, even in dry material.

On the basis of the overall dark colors and smooth caulocystidia, it would seem that X. brunneola O.K. Mill. could be close to X. setulipes but clearly differs by the non-branched or non-coralloid cheilo- and pileocystidia, the pileus trama not reacting in KOH solutions, the narrower spores (2–3 µm wide) and habitat in coniferous wood (Redhead 1988); the species seem not to be related phylogenetically, as X. brunneola is closer to X. campanella (see Figs. 3 and 4). Among those species of section Mutabiles (trama showing a positive color change in KOH), X. campanelloides Redhead is represented by collybioid, mostly fasciculate basidiomes (Redhead 1988: 488; Antonín and Noordeloos 2004), but this shows lobed, branched to coralloid thin-walled caulocystidia, and the presence of yellow pigment granules at the stipe medulla seems to be a characteristic feature, which we have not observed in X. setulipes. Another close species of this section is X. cornui (Quél.) J. Favre, originally described from central Europe; it develops in conifer forests (Larix decidua, Pinus montana Mill., etc.), but is typically found growing among Sphagnum. Apart from the habitat, this can be recognized by the discrete yellow granules on the pileus and stipe apex, circumcystidia turning reddish to reddish-brown in KOH, irregularly contorted to lobed caulocystidia restricted only to the stipe apex and a mild taste as in X. setulipes. A lectotype was designated by Redhead (1988: 496) for this small species, which has been illustrated by Courtecuisse and Duhem (1994) and Ludwig (2001: pl. 186, fig. 88.2). According to Redhead (1988), who studied numerous samples, it is not a rare species in North America, but was often formerly confused with X. cauticinalis (see Smith 1953). Xeromphalina fraxinophila is another member of section Mutabiles, which is close in some features to X. cornui (circumcystidia turning reddish in KOH); it is a more robust species (pileus 1–3 cm broad and stipe−3.5 mm wide), with yellowish lamellae; it shows caulocystidia similar in shape and length to X. setulipes, but clearly differs in habit, colors and the practical absence of cheilocystidia, which bear, if present, few simple lobes (like in X. cauticinalis). Xeromphalina parvibulbosa may have similar caulocystidia to X. setulipes, but its taste is bitter or astringent, and circumcystidia do not become reddish in KOH.
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Fig. 3

ITS Neighbor-joining consensus tree showing the relationships between Xeromphalina setulipes and its closest relatives. Bootstrap proportions from neighbor-joining and maximum parsimony, and posterior probabilities from bayesian maximum likelihood, and RAxML likelihood analyses are shown in this order next to nodes. Supporting values lower than 70% are not shown. Nodes supported by none or just a single inference method have no annotation

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Fig. 4

nLSU Neighbor-joining consensus tree showing the relationships between Xeromphalina setulipes and its closest relatives. Bootstrap proportions from neighbor-joining and maximum parsimony, and posterior probabilities from bayesian maximum likelihood, and RAxML likelihood analyses are shown in this order next to nodes. Supporting values lower than 70% are not shown. Nodes supported by none or just a single inference method have no annotation

Another representative from the northern hemisphere is Xeromphalina aspera Maas Geest. which was described growing on wood from Nepal (Maas Geesteranus (1992: 50); it shows a fasciculate growth, brown-reddish colors and is microscopically characterized by the pileus trama that turns reddish in KOH solutions, large lageniform cheilocystidia, a gelified pileipellis of smooth hyphae, and clavate to fusiform caulocystidia.

Screening the literature for Xeromphalina representatives from pantropical areas and the southern hemisphere, we have found that only a few species were described by Singer (1965) in a contribution on the genera Xeromphalina and Heimiomyces in South America (especially those from the east slope of the Andes and Brazil); he studied three species, X. helbergeri (which is also present in Central America and the Caribbean), X. tenuipes (widely distributed in the American continent), and X. austroandina; all these three are lignicolous, lack coralloid cheilocystidia and were gathered by Singer in diverse Patagonian forests (Nothofagus, Podocarpus, etc.). Later on, Singer (1989) contributed with two new lignicolous species (X. tropicalis and X. yungensis), from Brazil and Bolivia respectively.

None of the taxa described by Horak (1979) from Indomalaya and Australasia, either in Xeromphalina or in Heimiomyces, are morphologically similar to X. setulipes; all Xeromphalina species mentioned and described in this contribution show very different cheilocystidia, which are fusoid to lageniform and never coralloid; Horak (1968, 1979) also recognized Heimiomyces as an independent genus from Xeromphalina; it would seem that all Heimiomyces species macroscopically differ from Xeromphalina by the adnexed to broadly emarginate lamellae. Corner (1996) cited Heimiomyces tenuipes (Schwein.) Singer from Malesia; it is a common pantropical taxon that had previously also been recorded from South America, Africa, and the Caribbean (Singer 1965), as well as from North America (Redhead 1988). More recently, Maas Geesteranus and Horak (1995) described the new species Xeromphalina nudicaulis Maas Geest. & E. Horak from Papua New Guinea, growing on rotten roots of Fagaceae (Castanopsis and Lithocarpus), characterized by its “naked” covering (devoid of pileo- and caulocystidia), and fusoid-ventricose cheilocystidia.

We conclude that, from a morphological point of view, the combination of dark colors (brownish lamellae and uniformly blackish-brownish stipe), mild taste, smooth fusiform thick-walled caulocystidia, and branched to coralloid cheilo-and circumcystidia seems to be diagnostic for X. setulipes. The ecological patterns could also be a distinct characteristic of the new species, as X. setulipes has been found on soil in a Mediterranean ecosystem, specifically in a Quercus suber (΄alcornoque΄) forest with an undergrowth of typical Mediterranean shrub, mainly composed by Cistus and Juniperus.

Xeromphalina setulipes seems to be closely related to X. fraxinophila, X. cornui, X. campanelloides, and X. cauticinalis. This group shows clear genetic differences with the group formed by the species X. campanella, X. kauffmanii, X. brunneola, and probably X. junipericola, and also with the southern hemisphere taxa X. helbergeri and X. austroandina (Fig. 3). The analysis of more informative DNA regions such as the ITS or RPB2 loci from the whole group could help to clarify the internal organization of these clades. As mentioned above, a comprehensive morphological–molecular review of the genus is also needed in order to validate GenBank sequences, define the molecular species concept in this clade, and review the current morphological taxonomy of the genus.

Acknowledgements

We acknowledge L. Monje and A. Pueblas (Gabinete de Dibujo y Fotografía Científica at Alcalá University) for their valuable help in the treatment of digital images; the Spanish Ministry of Education and Culture for FPU grant AP2006-00890, the ΄Consejería de Agricultura y Medio Ambiente de la Junta de Comunidades de Castilla-La Mancha΄ for the Research Projects 2004X802, PAI08-0240-5097, and the Empleaverde Truficulture project from the Fundación Diversidad (cofinanced by the European Social Fund and the FGUA Cátedra de Medio Ambiente), which enabled us to carry out this study. We also want to thank Dr. G. Consiglio for his help in the Latin diagnosis and an anonymous reviewer for kindly helping in the grammatical correction of the manuscript.

Copyright information

© German Mycological Society and Springer 2010