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Research Article
A new species and a new record of Laccaria (Fungi, Basidiomycota) found in a relict forest of the endangered Fagus grandifolia var. mexicana
expand article infoAntero Ramos, Victor M. Bandala, Leticia Montoya
‡ Instituto de Ecología, A.C., Xalapa, Mexico
Open Access

Abstract

Two species of Laccaria discovered in relicts of Fagus grandifolia var. mexicana forests in eastern Mexico are described based on the macro- and micromorphological features, and their identity supported by molecular analysis of the internal transcribed spacer (ITS) and large subunit (LSU) of the ribosomal RNA gene. The phylogeny obtained here showed that one of the Mexican species is nested in an exclusive clade which in combination with its striking morphological features, infers that it represents a new species, while the other species is placed as a member in the Laccaria trichodermophora clade. This is the first report in Mexico of Laccaria with Fagus grandifolia var. mexicana trees, with which the reported species may form ectomycorrhizal association. Descriptions are accompanied with illustrations of macro- and micromorphological characters and a discussion of related taxa are presented.

Keywords

Ectomycorrhizal fungi, ITS, Neotropical fungi, nLSU, Tricholomatales

Introduction

It has long been recognized that Laccaria species are important ectomycorrhizal associates of ectotrophic plants worldwide (Mueller 1992). They are known to form interactions, for example with members of the Pinaceae, Dipterocarpaceae, Fagaceae, Betulaceae, Myrtaceae, Tiliaceae and Salicaceae (Kropp and Mueller 1999, Wilson et al. 2013). Some species as Laccaria laccata and L. bicolor have been considered host-generalists, and inclusive, have been subject of a lot of in vitro experimentation worldwide. However, recent studies developed based on molecular systematics showed that under those names, complexes of species are included (Taylor et al. 2006, Jargeat et al. 2010, Vincenot et al. 2012, Sheedy et al. 2013, Popa et al. 2014). A wide ectomycorrhizal host range has also been attributed to L. amethystina, but in this case it has some support for its generalist abilities at the population genetics level by Roy et al. (2008), while consideration for cryptic biological species was discarded, at least among the populations sampled in France.

In the monographic work of Laccaria by Mueller (1992), 19 species are recognized from North America, and 40 worldwide. New or potential undescribed species from different regions, based on morphological and molecular characteristics of fructifications, or on DNA identifications of environmental samples, have been discovered recently (Wang et al. 2004, Osmundson et al. 2005, Sheedy et al. 2013, Wilson et al. 2013, 2017, Montoya et al. 2015, Luo et al. 2016, Popa et al. 2014, 2016). Nowadays, MycoBank recognizes 112 records in this group of fungi, and additionally, Wilson et al. (2017) inferred 116 phylogenetic species from 30 countries covering the known geographic range of Laccaria. During the advances on the systematics of the group, a small number of morphological (macro- and microscopic) features had been found taxonomically informative (McNabb 1972, Mueller 1992), which may be the cause of false interpretations, leading to conceptual misunderstandings. In fact, since early taxonomic studies on the group, the need to revise the species of Laccaria commonly treated under names widely cited in the literature was considered as an important task, due to the existence of different, even undescribed species, confused under apparently well-known ones, such as in the groups of L. laccata (Scop.) Cooke and L. proxima (Boud.) Pat. (Singer 1967, Mueller and Sundberg 1981, Irving et al. 1985). For example, the study by Sheedy et al. (2013) based on DNA multigene sequences, even noted that cryptic phylogenetic species were not nested as sister taxa. Thus, strict species identifications and achieving phylogenetic inferences with stronger resolution in Laccaria, will aid in building a robust data set, dealing with each species ectomycorrhizal host range.

In Mexico, the reports of the diversity of the genus Laccaria include about 17 species (Aguirre-Acosta and Pérez-Silva 1978, Bandala et al. 1988, Montoya et al. 1987, 2015, Cifuentes et al. 1990, Pérez-Silva et al. 2006, Garibay-Orijel et al. 2009). The edibility and use of some species as food has been documented (e.g. Montoya et al. 1987, Montoya-Esquivel et al. 2002, 2003, Lampman 2007, Pérez-Moreno et al. 2008) and ectomycorrhizae formed under in vitro culture conditions, isolated from native specimens have also been achieved (Santiago-Martínez et al. 2003, Carrasco-Hernández et al. 2010, Galindo-Flores et al. 2015). Molecular studies on most of those records are needed not only to support their identifications but for being included in phylogenetic studies. Laccaria roseoalbescens T. J. Baroni, Montoya and Bandala, described as new (Montoya et al. 2015) from the mesophytic forest in Veracruz, was recognized under morphological features and confirmed through phylogenetic DNA sequence analyses and recently incorporated by Luo et al. (2016) in their molecular phylogeny to confirm the distinction of the new L. rubroalba X. Luo, L. Ye, Mortimer & K.D. Hyde from China.

We have under research the fungal community associated to the two southernmost relicts of mesophytic forests dominated by Fagus grandifolia var. mexicana in the American Continent. This tree species is currently in danger of extinction and in the Red list of Mexican cloud forest trees, inhabiting a narrow range of nearly 145 hm2 in Mexico (Rodríguez-Ramírez et al. 2013, Montoya et al. 2017). Taking into account its current status, we consider important to document the associated fungal species with particular focus to the ectomycorrhizal forming species. During our study, we found two species of Laccaria which after their morpho- and molecular analyses we concluded that with strong support can be recognized, one as L. trichodermophora G.M. Mueller and the other, as a distinct undescribed species close to L. angustilamella Zhu, L., Yang & L. Wang from China. As both are part of the unknown potential mycobionts of this endangered ectotrophic tree species, we were motivated to document them.

Materials and methods

Sampling and morphological study of basidiomes

Random visits were conducted during August–September 2005 and 2007, in two stands of Fagus grandifolia var. mexicana from Veracruz, Mexico, one in Acatlán Volcano, Acatlán (19°40'43.9"N; 96°51'9.8"W, 1840 m) and the other in Mesa de la Yerba, Acajete (19°33'37.2"N; 97°01'9.8"W, 1900 m). Basidiomes of Laccaria growing close to Fagus were gathered. Macromorphological characters and color were recorded, alphanumeric color codes in descriptions refer to Kornerup and Wanscher (1967). Measurements and colors of micromorphological structures were recorded in 3% KOH. Basidiospores were studied in Melzer’s reagent. Methods to determine spore ranges are those used by Montoya and Bandala (2003), with 45–50 spores measured per collection (length and width of the sporoid excluding the ornamentation) and given as a range with the symbol representing mean values. represents the basidiospore length/width ratio and is given as range of mean values. Line drawings were made with a drawing tube. The examined specimens studied are deposited in XAL herbarium (acronym from B. Thiers, continuously updated; Index Herbariorum: http://sweetgum.nybg.org/ih/). The SEM images were obtained after critical point drying of pieces of lamellae previously rehydrated in ammonia, fixed in glutaraldehyde and dehydrated in an ethanol series (Bandala and Montoya 2000).

DNA extraction, PCR amplification, and sequencing

Genomic DNA of the Mexican specimen was extracted according to Montoya et al. (2014). PCR was performed to amplify the ITS (Internal Transcribed Spacer) and LSU (Large Subunit) regions of the nuclear rDNA, using primers ITS1F, ITS5/ITS4, LR0R/LR21, LR7 (Vilgalys and Hester 1990, White et al. 1990, Gardes and Bruns 1993). PCR conditions, as well as procedures for the purification of amplified PCR products, cycle sequencing reactions and their purification were done according to Montoya et al. (2014). Once sequences were assembled and edited, they were deposited at GenBank database (Benson et al. 2017) (Table 1).

Laccaria taxa included in this study: samples, location and GenBank accession number for sequences.

Taxon Voucher Location GenBank
ITS 28S
Cortinarius violaceus MTS 4854 (WTU) USA: Washington DQ486695 DQ457662
L. alba AWW438 China: Yunnan-Shangrila JX504094 JX504178
L. alba F1120750 China JX504126 JX504206
L. alba F1121461 China JX504129 JX504209
L. alba GMM6131 China: Chang Bai Shan JX504131 JX504210
L. amethystea FP-98556 Germany: Vorpommern DQ499640
L. amethystea TUB 011464 Germany AF539737
L. amethysteo-occidentalis AWW556 USA: California, Nevada Co. JX504107 JX504191
L. amethysteo-occidentalis AWW590 USA: Oregon, Benton Co. JX504112 JX504195
L. amethystina ALB183 China: Tibet JX504092 JX504176
L. amethystina F1123822 USA: Wisconsin KU685760 KU685911
L. amethystina GMM7041 Russia: Caucasus KU685654 KU685797
L. amethystina GMM7621 France: Forest comaniale de Ste. Croix JX504150 JX504224
L. amethystina LaAM-08-1 JGI Genome JGI Genome
L. angustilamella BAP226 China: Yunnan JX504118 JX504201
L. angustilamella HKAS58714 China: Yunnan, Yongping JX504168 JX504244
L. aurantia KUN-F 78557-Type China: Yunnan JQ670895
L. aurantia MB-FB-101109 China: Yunnan JQ681209
L. bicolor AWW539 USA: Illinois KM067817 KU685763
L. bicolor AWW537 USA: Illinois, Johnson Co. JX504105 JX504189
L. major GMM6012 Costa Rica KU685758 KU685909
L. major GMM6019 Costa Rica KU685757 KU685908
L. nobilis F1091206 USA: Michigan KU685636 KU685779
L. ochropurpurea JMP0038 USA: Wisconsin EU819479
L. ochropurpurea KH_LA06_016 USA: Louisiana KU685721
L. ochropurpurea PRL3777 USA: Illinois KU685732 JX504246
L. ochropurpurea PRL4777 USA: Illinois KU685733 KU685883
L. proxima F1133825 USA: Mississippi KU685642 KU685786
L. roseoalbescens LM5042 Mexico: Veracruz KJ874327 KJ874330
L. roseoalbescens LM5099-Type Mexico: Veracruz KJ874328 KJ874331
L. salmonicolor GMM7596-Type China: Tibet JX504143 JX504218
L. salmonicolor GMM7602 China: Tibet JX504145 JX504220
L. sp. A0561 Japan: Sapporo JX504082
L. sp. A0573 Japan: Narusawa KU685617
L. sp. GMM6800 Guatemala KU685756 KU685907
L. squarrosa a DM121 Mexico: Veracruz MF669960 MF669967
L. squarrosa a DM63-Type Mexico: Veracruz MF669958 MF669965
L. squarrosa a DM93 Mexico: Veracruz MF669959 MF669966
L. trichodermophora TENN42523-Type USA: Texas DQ149868
L. trichodermophora F1111951 Costa Rica KU685640 KU685784
L. trichodermophora GMM7733 USA: Texas, Tyler Co. JX504157 JX504230
L. trichodermophora KH_LA06_013 USA: Louisiana KM067881 KU685872
L. trichodermophora GMM7735 USA: Texas KM067872
L. trichodermophora KH-LA06-012 USA: Louisiana KM067880
L. trichodermophora GMM7734 USA: Texas KM067871
L. trichodermophora KH-LA06-007 USA: Louisiana KM067874
L. trichodermophora KH-LA06-008 USA: Louisiana KM067875
L. trichodermophora tri1125225 USA: Rocky Mountains DQ149855
L. trichodermophora KH-LA06-010 USA: Louisiana KM067878
L. trichodermophora KH-LA06-011 USA: Louisiana KM067879
L. trichodermophora KH-LA06-009 USA: Louisiana KM067876
L. trichodermophora KH-LA06-009B USA: Louisiana KM067877
L. trichodermophora KH-LA06-004 USA: Louisiana KM067873
L. trichodermophora HC-PNNT-112 Mexico: Mexico State KT875031
L. trichodermophora GO-2009-266 Mexico: Mexico State KC152147
L. trichodermophora HC-PNNT-157 Mexico: Mexico State KT875032
L. trichodermophora GO-2009-305 Mexico: Distrito Federal KC152149
L. trichodermophora GO-2010-124 Mexico: Veracruz KC152144
L. trichodermophora EF36 Mexico KT354980
L. trichodermophora CB08167 Mexico: Mexico State KT875029
L. trichodermophora GO-2009-228 Mexico: Mexico State KC152146
L. trichodermophora GO-2010-126 Mexico: Veracruz KC152145
L. trichodermophora GO-2010-082 Mexico: Tlaxcala KC152152
L. trichodermophora GO-2009-225 Mexico: Mexico State KC152143
L. trichodermophora GO-2009-484 Mexico: Tlaxcala KC152151
L. trichodermophora HC-PNNT-192 Mexico: Mexico State KT875033
L. trichodermophora GO-2009-210 Mexico: Mexico State KC152148
L. trichodermophora HC-PNNT-132 Mexico: Mexico State KT875030
L. trichodermophora GO-2009-314 Mexico: Jalisco KC152150
L. trichodermophora HC-PNNT-099 Mexico: Mexico State KT875034
L. trichodermophora GMM7714 USA: Texas KM067867
L. trichodermophora GMM7712 USA: Texas KM067866
L. trichodermophora GMM7716 USA: Texas KM067869
L. trichodermophora HMJAU26938 KP128033
L. trichodermophora GMM7703 USA: Texas KM067865
L. trichodermophora GMM7697 USA: Texas KM067863
L. trichodermophora GMM7698 USA: Texas KM067864
L. trichodermophoraa Montoya 4393 Mexico: Veracruz MF669961 MF669968
L. trichodermophoraa Montoya 4394 Mexico: Veracruz MF669962 MF669969
L. trichodermophoraa AR24 Mexico: Veracruz MF669964 MF669970
L. trichodermophoraa Bandala 4282 Mexico: Veracruz MF669963
Psathyrella rhodospora MP133 MN DQ267129 AY645058

Phylogenetic methods

The phylogenetic analysis was performed with the sequences obtained in this study, as well as some retrieved from GenBank (http://www.ncbi.nlm.nih.gov/) derived from the Blast analysis (only those that best match), and complemented with related sequences used by Osmundson et al. (2005), Montoya et al. (2015) and Wilson et al. (2017) (Table 1). For this purpose, we constructed a dataset (ITS+LSU) using PhyDE v.0.9971 (Müller et al. 2010), also with MEGA 6.06 (Tamura et al. 2013) calculated the best evolutionary model and constructed the phylogenetic tree under the method of Maximum Likelihood (ML) with 500 bootstrap replications, and finally with MrBayes v 3.2.6 (Ronquist et al. 2012) constructed the phylogenetic tree (as Montoya et al. 2014) under the method of Bayesian Inference (BI). The phylogenies from ML and BI analyses were displayed using Mega 6.06 and FigTree v1.4.3 (Rambaut 2016) respectively.

Results

A total of 13 new ITS and 28S sequences for Laccaria were generated in this study (Table 1 and alignment in TreeBASE S21413). They were obtained from Laccaria samples proceeding from the two stands of Fagus grandifolia var. mexicana in the subtropical cloud forest in central Veracruz (sample AR24 comes from a conifers forest in Veracruz) (Table 1). Only bootstrap values of ≥70% and posterior probabilities (ML/PP) of ≥0.90 were considered and indicated on the tree branches. The phylogeny displayed (Fig. 1) inferred the Mexican samples clustered in two distinct clades. A group clearly related to Laccaria trichodermophora and another, in a separate clade, representing an undescribed species.

Figure 1. 

Phylogenetic relationships within Laccaria species inferred from the combined ITS and LSU sequence data by maximum likelihood method. Tree with the highest log likelihood (–4163.7219), the percentage of trees in which the associated taxa clustered together (only values ≥ 70% are considered) is shown next to the branches, followed by the posterior probabilities (only values ≥ 0.90 are indicated) obtained after Bayesian inference. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site.

Taxonomy

Laccaria squarrosa Bandala, Montoya & Ramos, sp. nov.

MycoBank No: 823034
Figs 2, 3, 4, 5

Holotype

MEXICO, Veracruz State, Mpio. Acatlán, Volcán de Acatlán, Aug 14 2007, DM 63 (XAL). Terrestrial under Fagus grandifolia var. mexicana.

Diagnosis

Differs from other species by having medium sized basidiomes, with pinkish to pale brownish-orange colors, smooth to finely squarrose surfaces, especially on the stipe, basal mycelium with whitish to pale brownish with pinkish tinges, and globose, echinulate basidiospores, 7–10 (-11.5) × 7–10.5 µm, with the echinulae 0.5–1.4 in length, 0.45–0.9 µm in width at base, subcylindrical to contorted cystidia and pileipellis arranged in a cutis with mounds of intermixed and irregularly projected hyphae.

Figure 2. 

Laccaria squarrosa, basidiomes. a, b habit c, d pileus surface details a, c DM 121 b DM 63 (holotype) d DM 93. Scale bars: 10 mm.

Figure 3. 

Laccaria squarrosa, lamellae attachment and habit. a, c DM 121 b DM 63 (holotype) d DM 93. Scale bars: 10 mm.

Figure 4. 

Laccaria squarrosa, a basidiospores b pleurocystidia c cheilocystidia d basidia a, c DM 121 b DM 63 (holotype) d DM 93. Scale bars: 5 µm (a); 10 µm (b–d).

Figure 5. 

Laccaria squarrosa, a–b basidiospores under SEM c–f details of the pileipellis c–d cutis (arrow indicating scales) e–f details of the pileipellis scales c–f DM 63 (holotype). Scale bars: 5 µm (a); 2 µm (b); 100 µm (c); 20 µm (d); 50 µm (e–f).

Gene sequences ex-holotype

MF669958 (ITS), MF669965 (LSU).

Etymology

referring to the characteristic squarrose surfaces of basidiomata.

Pileus 10–82 mm diam convex to plane-convex, at times slightly depressed at center, surface squamulose to squarrose with age, pinkish (6B3–2) with pale yellowish tinges towards the center or brownish-orange (5B6–5) when young; margin recurved, striate, edge thin. Lamellae 1–8 mm in length, adnate to subdecurrent, at times slightly undulate, subdistant or distant, pinkish to pale pinkish (6B4), 1–2 lamellulae per lamellae of different sizes. Stipe 50–155 × 5–9 mm, cylindrical, widened towards the base, squamulose to squarrose overall, more densely scaly towards the apex and when old, squamules brown, pinkish to ochraceous or ochraceous-orange. Basal mycelium pale whitish to brownish (6D6), with pinkish tinges in some areas. KOH negative overall surfaces.

Basidiospores 7–10 (-11.5) × 7–10.5 µm, =7.8–10.7 × 7.7–9.48 µm, =1.01–1.12, globose, pale brownish, thin walled, hyaline, inamyloid, echinulate; under SEM the echinulae appear acute, 0.5–1.4 in length, 0.45–0.9 µm in width at base, shorter towards the hylar appendix area, this latter structure (also called the apiculus) consisting of a tube with rounded ending. Basidia 35–66 × 10–15 µm, clavate to narrowly clavate, thin walled, mostly tetrasporic, at times tri- or bisporic, sterigmata 10 µm length, some with refringent contents, clamped, hyaline. Pleurocystidia 20–38 × 3–6 µm, subcylindrical, contorted, sinuous, hyaline, thin walled. Cheilocystidia 14–40 × 2–5 µm, subcylindrical, rarely narrowly utriform, contorted, sinuous, hyaline, thin walled. Pileipellis a regular compact cutis, hyphae periclinally oriented, also with projected mounds of intermixed hyphae, which form the pileus scales irregularly projected; hyphae cylindrical, some widened 4–10 µm diam, some septate, hyaline, inamyloid, yellowish in mass and somewhat refringent in some parts, thin walled, clamped. Context hyphae cylindrical, faintly yellowish in mass, 4–9 (-14) µm diam, thin walled, up to 1 µm diam, hyaline, inamiloyd, septate. Hymenophoral trama regular, compact, composed by cylindrical hyphae, pale yellowish in mass, 3–8 µm diam, septate, hyaline and inamyloid, thin walled. Clamps present.

Habitat

Terrestrial, solitary, under Fagus grandifolia var. mexicana.

Additional studied material

MEXICO, Veracruz, Mpio. Acatlán, Volcán de Acatlán, Sep 18 2007, DM 121. Mpio. Acajete, Mesa de la Yerba, Aug 28 2007, DM 93 (all at XAL).

Discussion

In the phylogeny presented here that is based on sequences used in the worldwide survey of Laccaria by Wilson et al. (2017) and complemented with some from GenBank (Fig. 1) and sequences of L. squarrosa, described here, this new taxon is clearly shown to be phylogenetically isolated from other Laccaria species. Laccaria squarrosa is distinct by possessing typical medium sized basidiomes with scaly surfaces, more obvious especially on the stipe and by having the basal stipe mycelium whitish to pale brownish with pinkish tinges. Microscopically it differs by globose, echinulate basidiospores, cylindrical cystidia and pileipellis arranged in a cutis with mounds of intermixed and irregularly projected hyphae. In Fig. 1, L. squarrosa is shown to be phylogenetically close to L. angustilamella Zhu L., Yang & L. Wang from China. This later species is characterized, however, by having a marasmioid to mycenoid habit, with a short basidiome size (pileus 20–30 mm diam), narrow (2 mm length) and subdistant lamellae, non-scaly stipe, with more ellipsoid basidiospores (Q up to 1.18) and larger echinulae (2.0–) 2.5–5.0 µm long and up to 2.5 µm wide at base (Wang et al. 2004).

Color features of the basidiomes and whitish mycelia relate Laccaria squarrosa to metasection Laccaria (Mueller 1992), where it superficially resembles L. proxima (Boudier) Patouillard. This later species, however, can be distinguished based on the longitudinally striate stipe, with a fibrillose surface only, ellipsoid basidiospores [9–11.5 × 6.7–8 (-8.8) µm, Q = 1.25–1.35 (-1.4)], having shorter echinulae (0.5–1 µm length), pleurocystidia absence and larger cheilocystidia [19–66.5(-92) × 2–8.5(-16.5) µm] (Mueller 1992). Among the species in the genus, Laccaria nobilis A.H. Smith, L. amethysteo-occidentalis G.M. Muell., L. trichodermophora and L. ochropurpurea (Berk.) Peck also produce fibrillose to somewhat scaly pileus surfaces. Laccaria ochropurpurea even can have recurved scales on the stipe surface. However, all those taxa clearly differ from Laccaria squarrosa by basidiomes and mycelia with violaceous colors, besides other macro and microscopical features (Mueller 1992).

Laccaria trichodermophora G.M. Mueller (Figs 67) was previously reported from Mexico (as L. farinacea sensu Singer) by Montoya et al. (1987) from conifer forests of Cofre de Perote National Park areas. The collections from Fagus grandifolia var. mexicana forest here studied, were collected in the locality of Mesa de la Yerba (Veracruz), on Aug 04 2005, Montoya 4393, Montoya 4394; Aug 28 2007, Bandala 4282 (XAL). Excepting by narrower hyphae disposed in the pileipellis mounds and the basidiospores including broadly ellipsoid to ellipsoid shapes, exhibit a similar morphological variation as those described by Mueller (1984, 1992) and other collections reported before from Mexico. A summary of the main morphological features that characterize the studied materials are: pileus 15–55 mm diam, fibrillose to fibrillose-minutely scaly, brownish-orange (6C6–C7), light brown or pale pinkish-brown or pale brownish towards the margin (6D6, 7C5–C4), hygrophanous. Lamellae 2‒6 mm in length, adnate to sinuate, close to subdistant, pinkish or incarnate (6A2‒B3). Stipe 20–75 × 2–8 mm, cylindrical, attenuated towards the apex, striate, fibrillose and fistulous. hygrophanous, concolorous to pileus but more pinkish-violaceous (13CD2) towards the base. Basal mycelium violaceous becoming white. Basidiospores 6–9 (-10) × 6–8.5 (-10) µm, = 6.9–8.18 × 6.84–7.9 µm, = 1.00–1.05, globose, hyaline, echinulate, under SEM the echinulae appear 0.8–1.13 × 0.6–0.8 µm. Basidia 27–65 (-80) × 7–13 µm, clavate, tetra or at times tri-sporic, hyaline, thin walled, clamped. Cheilocystidia 12–49 × 2–6 µm cylindrical to narrowly clavate, at times somewhat utriform, hyaline, thin walled, frequently clamped. Pileipellis composed of periclinally oriented hypahe 3–10 µm diam, in a more or less cutis arrangement but with frequent mounds of intermixed or erect hyphae, with terminal elements 25–125 × 10–13 µm, cylindrical to clavate other somewhat utriform 20–65 × 5–17 µm. Clamps present.

Figure 6. 

Laccaria trichodermophora, a basidiospores b pleurocystidia c basidia d pileipellis e cheilocystidia a–e Montoya 4393. Scale bars: 5 µm (a); 10 µm (b–c, e); 25 µm (d).

Figure 7. 

Laccaria trichodermophora, a–b basidiospores under SEM c–d pileipellis a, c–d Montoya 4393 b Bandala 4282. Scale bars: 1 µm (a–b); 50 µm (c); 25 µm (d).

In the phylogeny obtained (Fig. 1), the sampled sequences of this species appear in three clades. One of them, with collections from North America, included the type specimen (DQ149868) and 21 specimens from Mexico. Our collections clustered in this later lineage interestingly with one sample from Costa Rica too. The other two clades are composed of specimens from Texas, one of them sister to the type clade, and the third clearly separated, probably representing an undescribed species. A specimen (KP128033) labeled as L. trichodermophora in the GenBank, clustered in L. alba group from Asia in our analysis. This sample lacks geographic information and could well be a misidentified collection.

There are no previous reports of Laccaria trichodermophora being associated with Fagus grandifolia var. mexicana. This report serves as the first documentation of this association. According to the reports of L. trichodermophora, it shows a wide ecological range. Mueller (1992) observed that all collections of this Laccaria species from the southeastern United States appeared to be associated with Pinus. He also collected it, in Costa Rica, beneath Neotropical species of Quercus. In central Mexico, in the states of Tlaxcala and Michoacán, it has been recorded associated to mixed Pinus-Alnus and Pinus-Abies forests (Montoya et al. 1987, Montoya-Esquivel et al. 2004). In the eastern part of Mexico, in Veracruz, it has been found (as L. farinacea sensu Singer) in monodominant Pinus and mixed Pinus-Abies forests (Montoya et al. 1987). In this later country, it is interesting to note that, basidiomes of this species, specially from conifers, are sold in local markets as edible fungi (Montoya et al. 1987, Montoya-Esquivel et al. 2004). Based on the available ecological information of the samples in the phylogenetic tree (Fig. 1), a wide host range for L. trichodermophora type specimen clade can be inferred. Among the potential hosts, it can be recognized as occurring with Fagus grandifolia, Pinus elliottii, P. palustris and Quercus sp. in Texas, as well as P. patula, other species of Pinaceae and Quercus spp. in both US and in Mexico, and the endangered F. grandifolia var. mexicana as confirmed here. Abies religiosa represents another host also, as proved by data from two sequences (MF669964 and MF669970) (Table 1, Fig. 1) obtained here, from the sample AR24, from an A. religiosa forest at Cofre de Perote National Park in Veracruz, Mexico.

Acknowledgments

We appreciate the assistance in the field and in the laboratory by Biol. D. Ramos (at Instituto de Ecología, A.C.), Biól. J.C. Corona and Ing. Alicia García. We recognize the support given by CONACYT (CB 169172) to study the EcM fungi associated with Fagus grandifolia var. mexicana in the montane cloud forest of Central Veracruz and by the postdoctoral grant to A. Ramos. We acknowledge the support given by CONACYT (225382) to the Laboratorio de Presecuenciación, Red Biodiversidad y Sistemática, INECOL. M.Sc. Bertha Pérez at this lab aid in some molecular procedures.

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