Morphology

Macro-morphological descriptions and ecological observations were made in the field. Substrates were identified as fine woody debris (FWD) when wood diameters were 0.5–9 cm and coarse woody debris (CWD) when wood diameters were ≥ 10 cm. When growing on a living tree, the trees were identified from the Forest Dynamic Laboratory database, Pontificia Universidad Católica del Ecuador. Color terms used followed the “Mycological Colour Chart” and “Munsell soil color charts” [20, 21]. Micro-morphological characters were observed under a compound light microscope (Nikon E600®) using standard methods for the describing polypores [22]. Freehand cross sections of dried samples mounted with Melzer’s reagent, and/or, 3% NaOH, 5 and 10% KOH, sterile water, 1% Congo red, 1% phloxine, and 75% glycerol were prepared in order to observe spores. For hyphal systems and other individual structures, cross sections in 3% NaOH were incubated in a 60° C water bath for four hours, then vigorously shaken for one min at 20000 speed in the MagNA Lyser Roche®, dissected under the stereomicroscope (Nikon SM2800®) and mounted on water and/or the reagents listed above. Basidiospores and other structures were measured using a light microscope at 100x magnification with deionized water and/or reagents (n = 40 to 100 depending on the number of structures available within each sample). For basidiospores, shape terminology was that of the Stalpers database (https://russulales.mycobank.org/). Abbreviations are as follow: IKI+ = dextrinoid, IKI- = inamyloid and indextrinoid, CB+/- = cyanophilous/acyanophilous, ave = arithmetic mean, Q = the ratio of length/width of basidiospores.

Fungal isolations and cultural characterization

Using aseptic techniques, small pieces of wood substrates (~5 mm), from areas where rhizomorphs and basidiomata were attached to wood, were placed in 0.5% NaOCl solution for one minute, rinsed with running sterile water for ten seconds, and excess solution was removed with clean paper towels. The small pieces of wood were then placed in petri dishes containing malt agar with additives to prevent the growth of bacteria and contaminating Ascomycota. A semi-selective media (BSA) was used containing 15 g malt extract, 15 grams of agar, 2 g of yeast extract, 0.05 g benomyl, 0.5 g streptomycin and 1 L deionized water [23]. Isolates were monitored daily for growth and when mycelium extended 10mm, they were transferred to new plates. Fungal isolates were used for DNA extractions and to determine cultural characteristics.

For cultural characterization, two culturing media were used including malt extract agar (MEA) 15 g malt extract, 15 g of agar, 1 L deionized water and malt yeast agar (MYA) 15 g malt extract, 15 grams of agar, 2 g of yeast extract and 1 L deionized water [23]. Isolates were incubated at 24–26 C°. Six plates were used for each type of media. After five days, growth (mm) was determined using a digital caliper. Hyphal density, margins of the colony, color, and hyphal melanization were noted. Morphological descriptions and terms followed Stalpers (1978) [24].

DNA extraction, PCR amplification and sequencing

DNA extractions were made from pure cultures grown on MYA and/or from rhizomorphs, stipe, and/or pileus samples preserved in 95% ethanol following the CTAB extraction protocol Of Blanchette et al. 2016 [23]. When DNA extractions were from pure cultures, ¼ of fungal tissue on the petri (10 mm diameter) dish was scraped. When isolations were from other tissues, a 5 mm piece of tissue was cut into smaller pieces. Fungal tissue was suspended in 500 μl of cetyltrimethylammonium bromide (CTAB) lysis buffer with glass beads and vortexed for 1 minute for hyphal tissue and 5 minutes for pileus/stipe/rhizomorphs, samples were centrifuged for 30 seconds to aggregate fungal material. Supernatant was transferred to a new microcentrifuge tube and placed in a hot water bath at 65° C for 20 minutes. Subsequent, 500 μl of chloroform/phenol/isoamyl alcohol (25:24:1) was added to the tubes, shaken vigorously and centrifuged for 5 min at 15,000 rcf. The supernatant was then transferred to a clean microcentrifuge tube and isopropanol (stored at -20° C) was added (2/3 the amount of supernatant), tubes were inverted a few times and incubated at room temperature for 5 min. Tubes were then centrifuged for 7 min at 20,000 rcf, and supernatant was carefully removed. To the remaining DNA pellet, 500 μl of 70% ethanol (stored at -20° C) were added and centrifuged for 3 min at 20,000 rcf to wash the pellet. Ethanol was carefully removed, and tubes were left in a sterilized bio-safety cabinet to air dry. DNA was rehydrated with 100 μl of sterile water.

The partial regions of the nuclear ribosomal small subunit (SSU), nuclear ribosomal internal transcribed spacer (ITS), nuclear ribosomal large subunit (LSU), elongation factor 1-alpha (EF1-α) and the RNA polymerase II largest subunit (RPB1) were amplified by Polymerase Chain Reaction (PCR). The primers used for each region were: PNS1 with NS41 for SSU, ITS1F with ITS4 or ITS4B for ITS, LROR with LR7 or LR5 for LSU, EF1-983F with EF1-1567R for EF1-α and RPB1-Af with rpb1-Cr for RPB1 [25]. The PCR final volume was 25.5 μl, each tube containing 1 μl of DNA template, 1 μl of each primer (10 μM for RPB1 and 5 μM for the other regions), 0.5 μl of bovine serum albumin (BSA), 12.5 μl of GoTaq® Green Master Mix and 9.5 μl of sterile water in a thermocycler. PCR program for ITS and SSU were: 94° C for 5 min, 35 cycles of 94° C for 1 min, and 72° C for 1 minute, followed by a final extension step of 72° C for 5 min. For LSU: 95° C for 3 min, 94° C for 1min, 50° C for 45 sec, 74° C for 2 min ramping up 0.3° C/sec, 94° C for 1 min for 29 cycles and a final step of 72° C for 5 min. For EF1-α and PBB1 the same program was followed as: 94° C for 2 min, 94° C for 40 sec, 60° C for 40 sec decreasing 1° C per cycle, 72° C for 2 min,94° C for 40 sec for 8 cycles, 94° C for 45 sec, 53° C for 1:30 min, 72° C for 2 min, 94° C for 45 sec for 36 cycles and a final step of 72° C for 10 min.

Sequencing was carried out with Big Dye V3.1 and run on ABI 3730xl instruments (Functional Biosciences, Madison, WI, USA). Consensus sequences were assembled using Geneious 7.0 [26]. For samples with multiple DNA origins (pure culture, basidiomata and/or rhizomorphs), individual consensus sequences were created and then aligned to verify the DNA came from the same sample. When alignments had more than 99% pairwise identity, a single consensus sequence was created with all multiple DNA sequences to represent a specific sample. All final consensus sequences were compared through BLAST searches to GenBank sequences, whose identification has been supported with taxonomic publications to prevent sequences matching those wrongly identified. All sequences generated in this study were submitted to GenBank (Table 1).

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Table 1. Species list of Polyporus and related genera used in this study and GenBank entries.

https://doi.org/10.1371/journal.pone.0254567.t001

Phylogenetic analyses

All 135 newly generated sequences were deposited in GenBank, 28 SSU, 30 ITS, 28 LSU, 27 EF1, and 22 RPB1 (Table 1). However, not all sequences were used in the phylogenetic analysis but are available in GenBank for future taxonomic studies. SSU sequences were not included in the analyses as a multiple alignment of the region had 93% identical sites among all taxa, resulting in individual phylogenetic trees without clear delimitation of taxa. Ninety-six sequences from other studies available in GenBank were used in the analyses (Table 1).

Two datasets were constructed, the first based on two molecular markers (ITS and LSU), and the second on four molecular markers (ITS, LSU, RPB1, and EF1-α). Datasets included sequences generated in this study and reference sequences of Polyporus and allied genera downloaded from GenBank. Individual datasets for each region were aligned using Clustal Omega [27] sequence aligning tool and then manually examined and adjusted in Geneious 7.0 [25]. Due to the high variation of sequence length in the LSU alignment, sequences were trimmed to fit the length of most sequences, for shorter sequences, ends were filled with Ns. Alignments for the other regions were trimmed for an even length for all sequences. Annotations were made to identify polymorphisms (Indels and SNPs) on individual alignments of each molecular marker to identify variants frequency. The best-fit evolutionary model for each partition was calculated on JModelTest [28, 29] following the Bayesian Information Criterion (BCI). The Partition Homogeneity Test (PHT) was run on PAUP to test congruence [30]. Maximum-likelihood trees were generated on MEGA 10.05 tool [31] using the General Time Reversible model to choose the tree with the highest log likelihood with 1000 replicates and Gamma Distributed with invariant sites (G+I) for rates among sites. Bayesian Inference was calculated on Geneious 7.0 [26] using the General Time Reversible model, Gamma distribution, and subsampling frequency at 200 trees on a 1,100,000-chain length. Bayesian and Maximum-likelihood trees were matched to present results.

Nomenclature acts

The electronic version of this article in Portable Document Format (PDF) in a work with an ISSS or ISBN will represent a published work according to the International Code of Nomenclature for algae, fungi, and plants, and hence the new name contained in the electronic publication of a PLOS article are effectively published under that code from electronic edition alone, there is no longer any need to provide printed copies.

In addition, new names contained in this work have been submitted to MycoBank from which they will be made available to the Global Names Index. The unique MycoBank number can be resolved, and the associated information viewed through any standard web browser by appending the MycoBank number contained in this publication to the prefix http://www.mycobank.org/MB/. The online version of this work is archived and available from the following digital repositories: PubMed Central and LOCKSS.

Phylogenetic analysis

Eighty-eight of the 135 newly generated sequences were used in this study (25 ITS, 21 LSU, 22 EF1-α, and 20 RPB1). Another 96 related sequences (including 34 ITS, 32 LSU, 18 EF1-α, and 12 RPB1) used in the phylogenetic analyses were downloaded from GenBank and are listed in Table 1. Datasets were concatenated as follow: ITS-LSU resulted in an alignment with 1468 total characters (including 618 ITS + 850 LSU nucleotides) and ITS-LSU-RPB1-EF1- α with 3267 total characters (including 618 ITS + 850 LSU + 1232 RPB1 + 567 EF1-α nucleotides). The partition homogeneity test indicated that sequences in both datasets were not congruent (P-value = 0.01). In the first dataset, 756 characters were constant (proportion = 0.5), 120 variable characters were parsimony-uninformative, and 592 characters were parsimony-informative. For the second dataset, 1635 characters were constant (proportion = 0.5), 344 variable characters were parsimony-uninformative, and 1288 characters were parsimony-informative. In the Bayesian inference trees, for both datasets, total chain length was set up as 1,100,000, subsample frequencies at 200, and total samples analyzed were 4951. While in the Maximum-likelihood analysis, GTR+I+G model was used, and partitions were established considering individual markets. A discrete Gamma distribution was used to model evolutionary rate differences among sites (5 categories (+G, parameter = 0.5373)). The bootstrap consensus tree inferred from 1000 replicates where branches corresponding to partitions reproduced in less than 50% bootstrap replicates were collapsed. Initial trees for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the Maximum Composite Likelihood (MCL) approach, and then selecting the topology with superior log likelihood value [32]. One hundred twenty-one variants were found in the first dataset and four hundred seven variants in the second dataset. SNPs were the most common variants among datasets, being 74% and 85% respectively of the total variants found in each dataset (Table 2).

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Table 2. Variants’ analysis summary for individual alignments, ITS-LSU, and ITS-LSU-RPB1-EF1-α datasets.

https://doi.org/10.1371/journal.pone.0254567.t002

In both datasets, seven clades (“squamosus”, “guianensis”, “picipes”, “virgatus”, “neodictyopus”, “atroporus”, and “tuberaster”) consistently clustered with bootstraps and posterior probabilities higher than 70% support on nodes. Such clades were named after the genus and/or oldest recognized taxa for an easier identification in the phylogeny (Fig 1).

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Fig 1. Phylogeny of Polyporus and allied genera inferred from ITS+LSU+EF1-α+RPB1 data.

Topology is from Maximum-Likelihood analysis with bootstrap support values of nodes on light blue (≥70) and posterior probability values (≥70) of nodes on light green. Bold species are the newly described taxa in this study. ARG = Argentina, BRZ = Brazil, BLZ = Belize, CHN = China, CRI = Costa Rica, ECU = Ecuador, VNZ = Venezuela, and USA = United States.

https://doi.org/10.1371/journal.pone.0254567.g001

Samples analyzed in this study nested within the “squamosus”, “guianensis”, “neodictyopus”, and “atroporus” clades, all formed by neotropical taxa. The “Squamosus” and “guianensis” clades contain taxa currently accepted as Polyporus, while “neodictyopus” and “atroporus" contain former members of Polyporus.

Samples analyzed in this study nested within the “squamosus”, “guianensis”, “neodictyopus”, and “atroporus” clades. Only the “squamosus” and “guianensis” clades contain taxa currently accepted as Polyporus, while “neodictyopus” and “atroporus" contain former members of Polyporus.

The “squamosus” clade named after Polyporus squamosus (Huds.) Fr. was formed by sequences of P. squamosus, P. varius, P. hemicapnodes, P. leprieurii, and P. leprieurii var. yasuniensis variety novo. The last two formed an internal clade named “leprieurii” after Polyporus leprieurii Mont. This clade included samples from Ecuador (Yasuní), Costa Rica, and Belize. We have accepted as the “true” P. leprieurii the sequences from Costa Rica and Belize for the closer proximity to the type location, the French Guiana, as no sequence is available for the type collection. In this phylogeny, fifteen sequences from Yasuní were closely related to the “true” P. leprieurii. However, only six samples were designated to the newly proposed P. leprieurii var. yasuniensis, while the remaining sample, forming two well supported related clades within the “leprieurii” clade, need further taxonomical designation. P. hemicapnodes, an accepted synonym of P. leprieurii from China is closely related to the “leprieurii” clade, but forms its own well-defined clade (Fig 1).

The “guianensis” clade, named after P. guianensis Mont., was formed by sequences of P. guianensis from Argentina and Venezuela; three samples of P. taromenane species novo from Ecuador; and two samples from Ecuador plus one from Costa Rica previously misidentified as P. guianensis.

The taxa designated as Picipes clustered in two clades: “picipes” named after Picipes I.V. Zmitrovich & Kovalenko for having most sequences in this phylogeny, all from China, and “virgatus”, named after Picipes virgatus (Berkeley & M.A. Curtis) J.L. Zhou & B.K. Cui which had only two sequences, both from Argentina.

The “neodictyopus” clade, named after the Neodictyopus Palacio, Robledo, Reck & Drechsler-Santos genus was formed by taxa from Brazil, Ecuador and Belize. N. sylvaticus species novo was closely related to one of the sequences of N. dictyopus from Brazil. The sequence of the herbarium sample, EC-97, was closely related to different sequences of N. dictyopus from Brazil and P. dictyopus from Belize.

The “atroporus” clade, named after the Atroporus Ryvarden amend. Palacio, Robledo, Reck & Drechsler-Santos genus, included taxa from Brazil and Ecuador. A. tagaeri and A. yasuniensis species novo from Ecuador and A. diabolicus and A. rufoatratus from Brazil.

Finally, the “tuberaster” clade, named after Polyporus tuberaster (Jacquin ex Persoon) Fries consisted of two sequences from China. This clade was found to be very distinct from the other clades. The remaining taxa, P. umbelatus and P. hapalopus, both from China, did not cluster with any of the listed clades.

Taxonomy

Atroporus Ryvarden, Norw. J1 Bot. 20:2 (1973), emend. Palacio, Robledo, Reck & Drechsler-Santos.

Type species: Polyporus diabolicus Berk.

Type specimen: Brazil, Spruce 195 (K!)

Atroporus was proposed by Ryvarden (1973) based on swollen binding hyphae in the context of the type species, but this characteristic was considered too vaguely defined for a genus description [33]. Atroporus was later amended by Palacio, Robledo, Reck & Drechsler-Santos (2017), using basidiospore descriptions and Melzer reagent reaction of the skeletal-binding hyphae in the trama [17].

The genus shares macromorphological characteristics with the “Melanopus group”, which includes annual to biannual basidiomata, coriaceous when fresh and tough when dry; centrally to eccentrically stipitate, with a black cuticle on the stipe. Spores medium to large, 6–12 x 2–4 μm [4].

Description: “Basidiomata annual to biannual, centrally to eccentrically stipitate. Pileus circular; pilear surface glabrous, radially striate to finely wrinkled, dark purplish to red blackish; margins sterile, with a black cuticle. Pores circular. Context homogeneous, light brown. Stipe cylindrical, solid, bearing a black cuticle. Hyphal system dimitic with generative and skeletal-binding hyphae. Generative hyphae with clamp connections. Skeletal-binding from context and stipe abundant, arboriform, hyaline, IKI-. Skeletal-binding hyphae in the trama dextrinoid, with a differentiated wide stalk with sharply pointed apex. Basidia clavate, 4-sterigmate. Basidiospores narrowly ellipsoid to subcylindrical, thin-walled, smooth, hyaline, IKI-” [17].

Remarks: Basidiospores narrowly ellipsoid to subcylindrical, thin-walled, smooth, hyaline, IKI-. Hyphal system dimitic with generative and skeletal-binding hyphae. Generative hyphae present in trama with clamp connections; skeletal-binding hyphae in trama dextrinoid with a distinctive wide stalk with sharply pointed apex that aids in the identification of the genus. All species grow on dead wood, typically on dead fallen branches of relatively thin diameter trees [17].

1. Atroporus yasuniensis Toapanta-Alban, Ordoñez & Blanchette, sp. nov. Figs 2–4.

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Fig 2. Basidiomata and rhizomorphs of Atroporus yasuniensis.

A. gregarious habit of basidiomata. B. young basidiome. C. aged basidiome. C.1. pore layer. D. brown-reddish rhizomorphic mat on decayed wood formed posterior to rhizomorph attachment. E. Branching of rhizomorphs. F. fresh rhizomorphs with the active growing region white.

https://doi.org/10.1371/journal.pone.0254567.g002

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Fig 3. Microscopic features of A. yasuniensis.

A. Basidioles. B. Basidiospores. C. Cystidioles. C1 of the ventricose type and C2 oblong-like type. D. Thick-walled distinctive stalks of tramal hyphae. E. Generative hyphae with a thick-walled distinctive stalk pointed by the arrow. F. Skeletal-binding hyphae from context. G. Section of skeletal-binding hyphae from stipe. H. Generative hyphae from cuticle with melanized cuticle cells (arrow pointing to a clamp connection). Scale bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g003

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Fig 4. Cultural characteristics and microscopic features of A. yasuniensis.

A. macromorphology of colonies on MEA. B. Highly branched hyphae with simple septa and clamp connections. C. Macromorphology of colonies on MYA. D. Generative hyphae with numerous round-like swellings. B and D stained with Melzer’s reagent. Scales bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g004

Typus. Ecuador, Orellana Province, Yasuní Forest Dynamic Plot. Collected by C E Toapanta-Alban, 15 Jul 2017, Collection number: CTR-2-46. Found growing on dead wood of angiosperms.

Mycobank no.: MB 837970

Holotype: Fungarium number: QCAM7402 (QCAM)

    Collection number: CTR-2-46, Toapanta-Alban, December 2018

    GenBank no.: (ITS: MT950131), (LSU: MT9501610, (EF1-α: MW287083), (RPB1: MW287110), (SSU: MT950207).

Paratype: Fungarium number: QCAM7402 (QCAM)

    Collection number: CTR-2-46, Toapanta-Alban, July 2019

Etymology: yasuniensis (Yasuní = the paradise/God’s creation (from the Wao Terero language use by the Huaorani/Waorani Indigenous People living in the Amazon Rainforest between the Napo and Curaray Rivers in Ecuador)) + ensis (Latin suffix to denote origin). In reference to the site where samples were collected, Yasuní National Park in Ecuador.

Basidiomata annual, gregarious, centrally stipitate, up to and 6 cm tall. Pilei circular, depressed, infundibuliform with irregular wavy-striate margins that become more pronounced over time; up to 8 cm in diameter and 1.3 mm thick (Fig 2).

Pilear surface smooth, striate, shinny, white to dark-creamy when young; with age the surface remains shinny but becomes glabrous, bay to dark vinaceous (Munsell’s reference: 8. 1R/3.1/6.9; 10. ORP/3.4/4.3). Pilear texture coriaceous, and slightly tough; when dried rigid, slightly shrunken, blood colour to chestnut (Munsell’s reference: 2. 5r/2.3/5.9; 9. 5R/2.3/3.8). Pore surface white when young, creamy when aged, and pale brown when dried. In young specimens, pores are circular, radially arranged; in mature specimens, pores become slightly angular, elongated along the lobular areas near the margin and stipe; 7–10 per mm (ave = 8), 40–80 μm (ave = 59) (Fig 2 C1). Dissepiments entire, 10–38 μm (ave = 21). Tubes concolorous with pore surface, uniform not stratified, up to 0.30 mm; IKI+ reaction with tubes turning bright red. Context homogeneous, light brown, up to 1 mm thick; yellowish-brown in Melzer, weak IKI+ reaction. Stipe cylindrical, robust, solid, glabrous, bearing a lacquered cuticle; dark-reddish when young and black when aged, up to 4.5 mm diameter and up to 4.5 cm long.

Hyphal system dimitic with generative and skeletal-binding hyphae. In the trama, generative hyphae, hyaline, slightly branched with thin-walled sections 1–3 μm, simple septa and clamp connections (Fig 3).

Emerging from the generative hyphae, thick-walled distinctive stalks (up to 4.8 μm thick and 39–52 μm long) with pointing apex and 1–5 branches (1–3 μm) emerging from the middle and apical portion of the stalk; basal clamp connection. Skeletal-binding hyphae found in the trama, context, stipe, and rhizomorphs. Skeletal-binding hyphae in the trama and context of the arboriform type, hyaline, thin and thick-walled 1.5–4 μm, highly branched with simple septa. Skeletal-binding hyphae in the stipe and rhizomorphs are also of the arboriform type, somewhat less branched, hyaline, 1–4 μm thick, with simple septa. In the stipe, generative hyphae thin-walled with clamp connections holding cuticle cells. Cuticle cells brown-yellowish, thick 15–22 μm, 1–4 lobed with rounded ends, forming a palisade layer of groups of three or more cells forming crown-like arrangement. The hymenium is composed of paraphysoids structures (cystidioles, basidioles, and hyphidia) and basidia. Hyphidia, smooth, tubular (5–7μm wide), IKI-. Cystidioles can be of the ventricose type (10–16 x 2.8–8.5 μm) and oblong-like cells (10 x 6 μm). Basidioles abundant, round to clavate (9–16 x 6–8 μm). Basidia, 4-sterigmate, difficult to find free because basidia are encrusted in the hymenophore, only width measurements were recorded (6–8 μm wide). Basidiospores ellipsoid, narrowly ellipsoid to slightly cylindrical, thin-walled, hyaline, smooth, IKI-, 5–7 μm (ave = 6) x 2–4 μm (ave = 3), Q = 1.50–2.5 (ave = 2, n = 40).

Rhizomorphs, circular to slightly flat, solid, robust, coriaceous, thick (up to 5mm diameter), long (up to 3 m), well-branched, bearing a black-reddish lacquered cuticle with white-yellowish tips when fresh (Fig 2). Rhizomorphs are perennial (found growing for over four years in the same area), well distributed along the forest’s floor, emerging from decayed wood (coarse and fine woody debris). The formation of a rhizomorphic mat (brown-reddish tissue that becomes darker over time) facilitates the attachment to new substrates and other plant material on the forest floor. Rhizomorphs undergo anastomosis to form a complex rhizomorphic network. Rhizomorphs use trees and other surfaces to maintain upward growth. They occur on substrates accompanying basidiomata or alone.

Cultural characteristics: Cultures were easily obtained from rhizomorphs and colonized substrates. Initial growth is characterized by white, appressed, silky mycelium that can turn dark brown at different areas of the colony. Growth rate, characteristics of the mycelial mat, presence of aerial mycelium, and color of the colony are variable among colonies growing in the same media.

Growth rate is relatively slow on MEA 10–18 mm (ave = 13.5 mm) compared to MYA 14–31 mm (ave = 19 mm) after one month of growth (Fig 4).

On MEA, the marginal zone is irregular, usually submerged. When mycelium is submerged, pseudosclerotial plates are formed giving the agar a brown coloration and chamois-like appearance. Aerial mycelium is white, floccose, and crustose becoming brown, thick, coriaceous over time. On MYA, margins are regular to irregular, generally appressed, and rarely raised. Mycelium can be submerged and aerial. Aerial mycelium silky, floccose, cottony, white with dark colorations that are not as common as on MEA. Rhizomorphs rarely form on culture media but may be formed after long periods (6–12 months) of growth when nutrients apparently have been utilized (on MYA only).

In cultures, hyphal system is dimitic, with skeletal-binding hyphae in the white-aerial mycelium and generative hyphae in the melanized-crustose sections of mycelium. Skeletal-binding hyphae, highly to slightly branched, thin (1–2.5 μm wide) and thick-walled (2–4.5 μm wide); with simple septa; weakly IKI+ reaction as hyphae turned brown in the reagent; KOH-. Generative hyphae on crustose sections of mycelium are yellowish-brown to brown-reddish, thick-walled (2–8 μm wide) with abundant round-like swellings and clamp connections.

Substrate: Basidiomata and rhizomorphs emerge from decayed fine and coarse woody debris of angiosperms.

Distribution: known from the Amazon rainforest of Ecuador along valleys (temporarily flooded forests).

Specimens examined: Ecuador-Francisco de Orellana Province, Yasuní National Park (0° 41’ 0.5” S 76° 23’ 58.9” W). Samples collected from December 2016 to October 2019. Collection number: CTR-2-46.

Remarks: Atroporus yasuninensis was described from basidiomata and rhizomorphs collected over three years in an area of 20 x 10 m² in a temporarily flooded forest. It is characterized by gregarious, medium to big basidiomata (up to 10 cm), centrally stipitate. Pilei infundibuliform with irregular wavy-striate margins, up to 1.5 mm thick. Compared to A. yasuniensis, A. rufoatratus and A. diabolicus have relatively smaller basidiomata with thicker pilei and have been reported to have solitarily habit. Microscopically, A. yasuniensis has similarities with A. rufoatratus, with thick-walled distinctive stalks with pointing apex and 1–5 branches present in the trama. Cystidioles shape differs between A. rufoatratus and A. yasuniensis, with subulate cystidioles in A. rufoatratus and ventricose and oblong-like cystidioles in A. yasuniensis. Basidiospores are similar to other taxa in Atroporus; ellipsoid, narrowly ellipsoid, to slightly cylindrical, hyaline, smooth. Rhizomorphs cylindrical to slightly flat, solid, robust, flexible, coriaceous, well-branched, long, bearing a black-reddish cuticle. Rhizomorphs grow abundantly in A. yasuniensis; however, their development has not been established in A. rufoatratus and A. diabolicus.

2. Atroporus tagaeri Toapanta-Alban, Ordoñez & Blanchette, sp. nov. Figs 5 and 6.

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Fig 5. Basidiomata of Atroporus tagaeri.

A. Young basidiome with ongoing melanization of stipe. B. Dried basidiomata with fully melanized stipes and shrunken pileus. B.1 Pore layer. C. Fresh basidiome.

https://doi.org/10.1371/journal.pone.0254567.g005

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Fig 6. Microscopical features of A. tagaeri.

A. Basidioles. B. Basidium. C. Hyphidia. D. Basidiospores. E-F Hyphae from trama. E. Generative hyphae. F. Skeletal-binding hyphae G-H. Hyphae from context. G. Plectenchymatous thickenings. H. Skeletal-binding hyphae. I. Skeletal-binding hyphae from stipe. Scale bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g006

Typus. Ecuador, Orellana Province, Yasuní Forest Dynamic Plot. Collected by C E Toapanta-Alban,19 Jul 2017. Collection number: CTR-2-55. Found growing on dead wood of angiosperms.

Mycobank no.: MB 837972

Holotype: Fungarium number: QCAM7412 (QCAM)

    Collection number: CTR-2-55, Toapanta-Alban, July 2017

    GenBank no.: (ITS: MT950129), ((LSU: MT950159, (EF1-α: MW287084), (SSU: MT950205).

Etymology: tagaeri from the Huaorani language (Wao-Terero) in reference to the voluntarily isolated tribe, named after one of their members Tagae. Tribe living in and near Yasuní National Park, Ecuador.

Basidiomata annual, gregarious, centrally stipitate, up to and 4 cm tall. Pileus circular, convex to slightly umbonate with regular margins when young; circular, slightly depressed when old; up to 3 cm in diameter and 0.7 to 1 mm thick (Fig 5).

Pilear surface smooth, glabrous, isabeliline (Munsell’s reference: 0. 7Y/5.2/4.1) with brown vinaceous (Munsell’s reference: 5.OR/2.8/2.0) concentric discolorations near the margin when young; with age dark bay to dark vineaceous (Munsell’s reference: 8. 1R/3.1/6.9; 10. ORP/3.4/4.3. Pilear texture tender when young; coriaceous, robust when old; and rigid, slightly shrunken, when dried. Pore surface white greyish when young; whitish with buff sections (Munsell’s reference: 1.2y/8.1/4.1) when aged; dark buff (Munsell’s reference: 1.2y/8.1/4.1) when dried. Pores circular to slightly angular, 6–9 per mm (ave = 7), 45–90 μm diameter (ave = 68) (Fig 5B1). Dissepiments entire, 30–90 μm (ave = 50). Tubes concolorous with pore surface, uniform not stratified, up to 0.40 mm; IKI+ reaction with tubes turning bright red. Context homogeneous, creamy when fresh; light brown when dried, up to 0.4 mm thick; IKI-. Stipe cylindrical, solid, glabrous, bearing a reddish lacquered cuticle at the base and white near the pileus when young; opaque, dark-reddish to black when aged; up to 3 mm diameter and 1.5–3.5 cm long.

Hyphal system dimitic with generative and skeletal-binding hyphae. In the trama, generative hyphae hyaline, highly branched with thin (2–3 μm) and thick-walled (2–5.5 μm) sections; simple septa and clamp connections. Thin-walled sections along branches and thick-walled sections on the main stem (Fig 6).

Skeletal-binding hyphae found in the trama, context, and stipe. In the trama and context, skeletal-binding hyphae are of the arboriform type, hyaline, thin and thick-walled 1–4 μm, highly branched with simple septa. In context, hyphal modifications are frequent as segments of plectenchymatous thickenings (4–10 μm wide and 39–120 μm long) with simple septa. Skeletal-binding hyphae in the stipe also of the arboriform type, hyaline, 1–4 μm wide with simple septa. The hymenium is composed of paraphysoids structures (cystidioles, basidioles, and hyphidia) and basidia. Hyphidia, smooth, tubular, 3–3.5 μm (ave = 2.7) wide, IKI-. Cystidioles rare, of the ventricose type (10 x 6 μm). Basidioles abundant, clavate 4.3–6.3 μm wide x 10–15 μm length (ave = 6 x 13μm). Basidia, clavate, 4-sterigmata, difficult to find free, (7 x 26 μm). Basidiospores narrowly ellipsoid, thin-walled, hyaline, smooth, IKI-, 5.5–8 μm (ave = 6) x 2.6–4 μm (ave = 3), Q = 1.6–2.12 (ave = 1.90, n = 40).

No rhizomorphs were associated with basidiomata.

Cultural characteristics: No cultures were obtained.

Substrate: Basidiomata emerge from decayed fine woody debris of angiosperms.

Distribution: Known from the Amazon rainforest of Ecuador along ridges and slopes (tierra firme forest).

Specimens examined: Ecuador-Francisco de Orellana Province, Yasuní National Park (0° 41’ 0.5” S 76° 23’ 58.9” W). Samples collected on July 2017. Collection number: CTR-2-55.

Remarks: Atroporus tagaeri was described from samples collected in an area of 1m² in terra firme forest. It is characterized by gregarious, small to medium basidiomata (up to 4 cm), centrally stipitate. Pilei circular, slightly depressed with regular margins, up to 3 cm diameter and 1 mm thick. In terms of shape and size, A. tagaeri is similar to A. rufoatratus, however, A. tagaeri has thinner pilei. Hyphal system dimitic, with generative and skeletal-binding hyphae, similar to other taxa in Atroporus. The distinctive thick-walled stalks with pointing apex, aid in the description of the genus were not found in the examined specimens. Cystidioles are less frequent in A. tagaeri than in A. yasuniensis, A. rufoatratus, and A. diabolicus. Plectenchymatous thickenings are abundant in the context and not registered for other taxa in the genus. Basidiospores are similar to other taxa in the genus; narrowly ellipsoid, thin walled, hyaline, IKI-. No rhizomorphs found associated with basidiomata.

Neodictyopus Palacio, Robledo, Reck & Drechsler-Santos, PLoS ONE 12(10), e0186183, (2017)

Type species: Neodictyopus atlanticae.

Type specimen: Brazil, Santa Catarina, Santo Amaro de Imperatriz, 15 Nov 2013, ER, Drechsler-Santos DS1285 (FLOR 60309)

Neodictyopus was proposed by Palacio, Robledo, Reck & Drechsler-Santos (2017) after decrypting the Polyporus dictyopus species complex. The genus was proposed using specimens collected in Brazil-Mato Groso morphologically linked to the type specimen from Chile-Juan Fernández archipelago. Neodictyopus was established as a neotropical genus, but it could be presumably present pantropically. Palacio et al. (2017), recommended carrying out surveys and collections from the type locality in order to define the circumscription and distribution.

The genus is also part of the “Melanopus group” since it shares the macromorphological similarities previously described.

Description: “Basidiomata annual, lateral to eccentrically, rarely centrally stipitate; pileus reniform to flabelliform; pilear surface glabrous, radially striate, dark reddish brown; margin irregular, wavy and lobed to decurved and entire. Pores circular. Context homogeneous, yellow to light brown. Stipe cylindrical, solid, reticulated to longitudinally striate, bearing a black cuticle. Hyphal system dimitic; generative hyphae clamped, hyaline, thin-walled. Branched skeletal-binding hyphae dominating, arboriform, hyaline, IKI- to slightly dextrinoid (only in mass) in the trama of the tubes. Basidia clavate, 4-sterigmate. Subcylindrical to bacilliform, thin-walled, smooth, hyaline, IKI-.” [17].

Remarks: Basidiomata lateral to eccentrically stipitate; pileus reniform to spatulate. Hyphal system dimitic, with clamped generative hyphae and skeletal-binding hyphae of the arboriform type, slightly dextrinoid (in mass only) in the trama. Basidiospores subcylindrical to bacilliform. Distributed along the Neotropics, however, might be pantropical. All species grow on dead wood producing white rot on the substrate. Neodictyopus is morphologically similar to taxa within the Polyporus and Atroporus genera. However, Neodictyopus differs from the type species of Polyporus (P. tuberaster) in the texture of the pileus and from Atroporus by the spore shape and the strong dextrinoid reaction in the skeletal-binding hyphae in the trama proper of Atroporus.

3. Neodictyopus sylvaticus Toapanta-Alban, Ordoñez & Blanchette, sp. nov. Figs 7 and 8.

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Fig 7. Basidiomata of Neodictyopus sylvaticus.

A. Gregarious habit of basidiomata on substrate. B. Hymenium layer. B.1 Pore layer.

https://doi.org/10.1371/journal.pone.0254567.g007

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Fig 8. Microscopical features of N. sylvaticus.

A. Basidium. B. Basidiospores. C. Hyphidia. D. Tramal setae. E. Hyphae from trama with segments of plectenchymatous thickenings. F-G. Hyphae from context. F. Highly ramified skeletal-binding hyphae. G. Thin-walled sections of skeletal-binding hyphae from context. Scale bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g008

Typus. Ecuador, Orellana Province, Yasuní Forest Dynamic Plot. Collected by C E Toapanta-Alban, 22 Jul 2017. Collection number: CTR-2-60. Found growing on dead wood of angiosperms.

Mycobank no.: MB 837973

Holotype: Fungarium number: QCAM7418 (QCAM)

    Collection number: CTR-2-60, Toapanta-Alban, 22 Jul 2017

    GenBank no.: (ITS: MT950155), (LSU: MT950183, (EF1-α: MW287085), (RPB1: MW287111), (SSU: MT950229).

Etymology: sylvaticus from Latin sylva (“forest”), in reference to the geographical region where specimens were found, Amazon rainforest of Ecuador.

Basidiomata annual, gregarious, centrally to eccentrically stipitate, up to and 2.5 cm tall. Pileus reniform to flabelliform with regular to irregular wavy margins; up to 2.3 cm in diameter and 0.83–1.6 mm thick (Fig 7).

Pilear surface smooth, glabrous, yellow-creamy to pale luteous (Munsell’s reference: 2. 4Y/8.5/7.0) when young; sienna, dark bay to dark vinaceous (Munsell’s reference: 6. OYR/5.1/10.8; 8. 1R/3.1/6.9; 10. ORP/3.4/4.3) when old and dried. Pilear texture coriaceous when fresh and slightly shrunken and rigid when aged. Pore surface light creamy when fresh; creamy to light-brown with pale hazel hues (Munsell’s reference: 9. OYR/5.5/3.7) when dried. Pores circular to slightly angular, 6–9 per mm (ave = 7), 45–90 μm diameter (ave = 70); pores are not evenly formed in the hymenium as some regions lack pores (Fig 7B1). Dissepiments entire, 45–110 μm (ave = 80). Tubes concolorous with pore surface, uniform not stratified, 0.30–0.40 mm; IKI+ reaction with tubes turning bright red. Context homogeneous, light to dark brown, up to 1 mm thick; IKI-. Stipe flat, robust, solid, glabrous, bearing black cuticle, up to 5 mm diameter, 2 mm thick, and 5 mm long.

Hyphal system dimitic with generative and skeletal-binding hyphae. In the trama, generative hyphae, hyaline, highly branched with thick and thin-walled sections; thicker sections, slightly rounded, 3–5.5 μm along the main stem and thinner sections 2–3 μm on branches; simple septa and clamp connections (Fig 8).

Skeletal-binding hyphae of the arboriform type, abundant, in trama, context, and stipe, hyaline, thin and thick-walled 1.5–4.5 μm; simple septa. In trama, hyphal modifications are frequent as segments of plectenchymatous thickenings (3–18 μm wide and 19.5–105.5 μm long) with simple septa. Tramal setae found embedded in the tubes, rare, of the ventricose type, slightly hooked, thick-walled, (20–30 μm long x 6–12 μm wide). The hymenium is composed of hyphidia and basidia. Hyphidia, smooth, tubular, 2–5 μm (ave = 3.5) wide. Basidia, rare, narrowly clavate, 4-sterigmata, (6 x 26 μm). Basidiospores narrowly ellipsoid to cylindrical, thin-walled, hyaline, smooth, IKI-, 5–7 μm (ave = 6) x 2.5–3.5 μm (ave = 2.7), Q = 1.8–2.5 (ave = 2.15, n = 40).

No rhizomorphs were found associated with basidiomata.

Cultural characteristics: No cultures were obtained.

Substrate: Basidiomata emerge from decayed fine woody debris of angiosperms.

Distribution: Known from the Amazon rainforest of Ecuador along ridges and slopes (tierra firme forest).

Specimens examined: Ecuador-Francisco de Orellana province, Yasuní National Park (0° 41’ 0.5” S 76° 23’ 58.9” W). Samples collected on July 2017. Collection number: CTR-2-60.

Remarks: Neodictyopus sylvaticus was described from samples collected in an area of 1m² in terra firme forest. It is characterized by gregarious, small basidiomata (up to 3 cm), centrally to eccentrically stipitate. Pilei reniform to flabelliform with regular to irregular wavy margins, up to 2.5 cm diameter and 1.5 mm thick. In terms of shape, N. sylvaticus is similar to N. dictyopus, however, N. sylvaticus has smaller basidiomata with thinner pilei. Stipe is short, flat, solid, robust, which differ from the other taxa in the genus, described to have circular stipes. Hyphal system dimitic, with generative and skeletal-binding hyphae. Generative hyphae are distinctive from other taxa in the genus. These are highly branched, thin and thick-walled, slightly rounded along the main stem. In trama, hyphal modification as plectenchymatous thickenings are common. Such hyphal modifications also found in the context of A. tagaeri, but not reported in any other taxa in Neodictyopus. Tramal setae embedded in tubes are very rare, reported to N. sylvaticus but not in other taxa in Neodictyopus or allied genera. Basidiospores narrowly ellipsoid to cylindrical. Rhizomorphs have been reported for P. dictyopus, however, no rhizomorphs were found associated with N. sylvaticus.

Herbarium sample examined

4. Neodictyopus sp.

Collection label: Ecuador, Sucumbios Province, Lago Agrio, Camino Los Salideros. Cuyabeno Wildlife Reserve, 0° 00’ N 76° 10’ W, 250 meters above sea level. Collected by Jean Lodge, 8 May 1993. Collection number: EC-97. Found growing on wood-branches. Fig 9.

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Fig 9. Basidiomata of Neodictyopus sp. Ec-97.

A. Dried basidiome. A1 Pore layer.

https://doi.org/10.1371/journal.pone.0254567.g009

Mycobank no.: As species rank was not determined, the sample was not accessioned in Mycobank.

Fungarium number: EC-97 (CFMR), in Center for Forest Mycology Research (Fungi of Napo).

GenBank no.: (ITS: MT950132)

Basidiome annual, eccentrically stipitate, solitary, up to 3 cm tall. Pileus reniform to flabelliform with regular margins; up to 3 cm in diameter and 1 mm thick. Pilear surface smooth, glabrous, dark bay to dark vinaceous (Munsell’s reference: 6. OYR/5.1/10.8; 8. 1R/3.1/6.9; 10. ORP/3.4/4.3) (Fig 9).

Pilear texture rigid. Pore surface greyish to dark brown. Pores circular, 7–11 per mm (ave = 9), 41–62 μm diameter (ave = 51). Dissepiments entire, 39–81 μm (ave = 56). Tubes concolorous with pore surface, up to 0.30 mm thick, IKI+. Context homogeneous, light to dark brown, up to 0.7 mm thick; IKI-. Stipe circular, solid, glabrous, bearing a black cuticle, up to 2.5 mm diameter and 8 mm long.

Hyphal system dimitic with generative and skeletal-binding hyphae. Generative hyphae, hyaline, highly branched, thin-walled 1–3 μm, simple septa and clamp connections. In trama, thick-walled distinctive stalks with slightly rounded pointing edges and 1–3 branches located from the middle portion to the tips, 50–81 μm (ave = 62.6 μm) long and 2–4.5 μm (ave = 3.2 μm) wide with a basal clamp connection. Skeletal-binding hyphae of the arboriform type found in trama, context and stipe, hyaline, thin and thick walled; thin-walled sections 1–3 μm along branches and thick-walled sections along the main stem 2–7 μm. In context, hyphal modifications are frequent with segments of plectenchymatous thickenings 40–145.5 μm (ave = 68 μm) long and 3.6–8 μm (ave = 6.4 μm) wide; clamp connections observe where ramifications start. Hymenium composed of paraphysiods structures (cystidioles, basidioles, and hyphidia). Hyphidia, smooth, tubular, thin-walled. Cystidioles of the ventricose type 8–18 μm x 3–6.5 μm. Basidioles, clavate, 7.5–12.7 μm x 3.6–5.8 μm. Basidia not found. Basidiospores not found, however, measurements found on collection label are: 5–7 x 2.5–3.5 μm, Q = 1.6–2.3 (ave = 1.9); ellipsoid to narrowly ellipsoid, slightly cylindrical.

Cultural characteristics: EC-97 Isolate was provided by the USDA Forest Products Laboratory, Center for Forest Mycology Research, Madison, Wisconsin, USA. Cultures were successfully maintained in MYA only; slow growth rate, 10 mm during a month of growth. Cultures highly melanized with, rare formation of aerial mycelium. With time, aerial mycelium forms a dark coriaceous, scar-like tissue, with concentric black discolorations, very tough and difficult to cut.

Substrate: wood-branches.

Distribution: Known from the Amazon rainforest of Ecuador.

Specimen examined: Ecuador-Sucumbíos Province, Camino Los Salideros, Cuyabeno Wildlife Reserve, 0° 00’ N 76° 10’ W, 250 m.a.s.l. Collected by Jean Lodge, 8 May 1993. Collection number: EC-97.

Remarks: The herbarium sample examined was collected in Cuyabeno Wildlife Reserve, Ecuador in 1993. It was previously determined as P. leprieurii, however, based on macromorphological characteristics and phylogenetic analysis we determined this sample belongs to Neodictyopus. This specimen is characterized by basidiome, eccentrically stipitate, solitary; pile reniform, dark vinaceous. Stipe, circular, short, bearing a black cuticle. Macromorphological characteristics in terms of shape and color are similar to N. dictyopus, however it has a smaller basidiome. Cystidioles of the ventricose type, which are different in shape to the ones present in N. atlanticae and N. dictyopus with subulate cystidioles. Thick-walled distinctive stalks with rounded pointing-edges and 1–3 branches are present in trama, similar structures present in most species of Atroporus. In context, plectenchymatous thickenings are abundant. The presence of rhizomorphs was not annotated on the label, however, P. dictyopus, which is closely related to this taxon, has been reported to develop rhizomorphs.

Polyporus P. Micheli ex Adans., Familles des plantes 2: 10 (1763)

Type species: Polyporus tuberaster (Jacq. Ex Pers.) F., Systema Mycologicum 1:347 (1821)

Type specimen: Plate 71, Fig 1 in Micheli (1729), was selected as lectotype in Ryvarden (1991)

Polyporus accommodates many morphologically heterogeneous species. Taxa within the genus has been accommodated in six infrageneric groups. The genus has undergone important taxonomical changes since it first was proposed. Initial changes were based on macro and micromorphological observations [34]. The later changes were made with the development of molecular biological techniques that allowed to identify the phylogenetic relationships within the taxa under Polyporus [15–18]. More taxonomic changes are likely to occur as more sophisticated phylogenetic studies are available.

Description: The type concept followed in this study refers to species with stipitate basidiomata growing on wood or arising from a sclerotium. Basidiomata can be annual or biannual, centrally, eccentrically, or laterally stipitate. Pilei can be circular to dimidiate, convex to infundibuliform; pilear surface smooth to scaly, glabrous to finely tomentose, white to deep brown or black; pilear texture tough when fresh, leathery, or brittle when dry. Pore surface white to creamy, or dark brown when dry. Pores entire, circular to angular, small to large, decurrent or not on the stipe. Stipe creamy to black, glabrous to finely tomentose, with or without a cuticle, smooth to longitudinally wrinkled, in some. Hyphal system dimitic, with arboriform vegetative hyphae; generative hyphae hyaline with clamp connections and simple septa and skeletal-binding hyphae hyaline to brown, solid, or with a lumen. Cystidia none. Hyphal pegs present or absent. Basidia clavate, 4-sterigmate. Basidiospores cylindrical to subellipsoid, straight to slightly bent, thin-walled, smooth, hyaline, IKI-. Substrate, woody debris of angiosperms, conifers, or developing from sclerotia buried in the ground. Species are mostly saprophytes and rarely parasites, causing white rot on wood [4].

Remarks: Polyporus is a heterogeneous genus, cosmopolitan with ecologically diverse species. The description provided above is almost universally accepted. It focused on stipitate basidiomata with a dimitic hyphal system of the arboriform type and skeletal-binding hyphae. Basidiospores cylindrical to subellipsoid, IKI-. Substrate, woody debris of angiosperms, conifers, or developing from sclerotia. Allied genera sharing some macro and micromorphological characteristics are Echinochaete, Favolus, Atroporus, and Neodictyopus. Such characteristics include, stipitate basidiomata; hyphal system dimitic; basidiospores cylindrical to subellipsoid, smooth, hyaline. Echinochaete differs from Polyporus for having setae-like, dark brown organs, partly in the dissepiments, partly on the pileus [4, 35].

Herbarium sample examined

5. Polyporus leprieurii Mont.

Collection label: Cayo District-Belize, Maya Mts., Northern foothills, Blue hole National Park on Hummingbird Hwy. (Hummingbird Loop trail). Collection number: LR44178, Collected by Leif Ryvarden, 15 Nov 2001. Fig 10.

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Fig 10. Basidiomata of Polyporus leprieurii, BZ-958.

A. Dried basidiome. A1 Pore layer.

https://doi.org/10.1371/journal.pone.0254567.g010

Fungarium number: BL-958 (CFMR), in Center for Forest Mycology Research (Fungi of Belize).

GenBank no.: (ITS: MT950154)

Etymology: leprieurii was used after François Mathias René Leprieur, a French pharmacist and naturalist established in Cayenne-French Guiana.

Basidiome annual to biannual, centrally to laterally stipitate (Fig 10).

Pileus reniform to flabelliform with regular margins; 0.5–0.9 mm thick. Pilear surface and texture, smooth, glabrous, rigid; ochraceous, brick, sienna, umber (Munsell’s reference: 10. OR/5.6/6.5; 6. OYR/5.1/10.8; 7. Oyr/3.7/5.8) when dry. Pore surface light brown to pinkish when dried. Pores circular to angular, slightly elongated near margins, 7–11 per mm (ave = 8), 64–90 μm diameter (ave = 80). Dissepiments entire, 25.5–60 μm (ave = 42). Tubes concolorous with pore surface, up to 0.30 mm thick, IKI+. Context homogeneous, light brown, up to 0.63 mm thick; IKI- reaction. Stipe circular, solid, glabrous, bearing a black cuticle, up to 1.5 mm diameter.

Hyphal system dimitic with generative and skeletal-binding hyphae. In the trama, generative hyphae, hyaline, highly branched, thin-walled 1–2.5 μm, simple septa and clamp connections. Skeletal-binding hyphae of the arboriform type, abundant in trama and context, thin and thick walled; thin-walled 1–2.5 μm along branches and thick-walled along the main stem 2.5–4.5 μm. Hymenium composed of paraphysiods structures (basidioles, and hyphidia) and basidia. Hyphidia tubular, smooth, thin-walled, 3.4–6 μm. Basidioles abundant, clavate, 7.5–12.7 x 3.6–5.8 μm. Basidia clavate, four-esterigmate, 20–30 (ave = 21) μm x 4.5–6 (ave = 5) μm. Basidiospores ellipsoid to narrowly ellipsoid, thin-walled, hyaline, smooth, IKI-, 4.5–6.6 (ave = 5.5) μm x 2–3.3 (ave = 2.7) μm, Q = 1.6–2.3 (ave = 2)

Substrate: deciduous wood, mixed broadleaf.

Distribution: Tropical to subtropical species in America and Eastern Asia [Nunez & Ryvarden, 1995].

Specimen examined: Cayo District-Belize, Maya Mts., Northern foothills, Blue hole National Park on Hummingbird Hwy. (Hummingbird Loop trail), 17° 8’ 51” N 88° 40’ 00” W. Collected by Leif Ryvarden, 15 Nov 2001.

Remarks: The species was described by Camille Montagne in 1840 while describing other taxa from French Guiana. P. leprieurii share macromorphological characteristics with members of the “Melanopus group”. The specimen examined was from the Center for Forest Mycology Research, Wisconsin, was determined as P. leprieurii by Leif Ryvarden in 2001. It is a partial specimen cut into three pieces; size cannot be determined. Pilear surface smooth, glabrous, ochraceous; rigid texture as dried. Pore surface light brown to pinkish when dry. Pores circular to angular. Stipe solid, glabrous, bearing a black cuticle. Basidiospores ellipsoid to narrowly ellipsoid. Hyphal system dimitic with generative and skeletal-binding hyphae. The production of rhizomorphs is well documented in this taxon; however, their presence was not established on the collection label. P. leprieurii is known to be distributed in tropical and subtropical areas in America and East Asia. According to “The Global Fungal List”, most records are in Brazil while others are in the Americas (North, Central, and South America), the Caribbean region, Africa (Congo, Cameroon), Northern Asia (Russia), East Asia (China), South and Southeast Asia (India, Sri Lanka, Singapore), and Oceania (Australia, Samoa, Papa New Guinea). Obligated synonyms are P. hemicapnodes Berk. & Broome, P. pusillus Rostr., P. calyculus Pat., & Gaillard, P. savoyanus Pat., Revue, P. subelegans Murrill, P. tephromelas Mont., and P. atripes Rostr. In terms of shape and size, P. leprieurii is similar to Neodictyopus, however, the color of the pilei differs, with light orange to ochraceous hues in P. leprieurri and Neodictyopus with dark-brown to darker-reddish hues. Presumably, P. leprieurri could be a species complex that needs further revision to unveil the phylogenetic relationships among specimens in tropical and subtropical regions as macromorphological variations are not obvious between samples in tropical and subtropical regions.

6. Polyporus leprieurii var. yasuniensis (Mont.) Toapanta-Alban, Ordoñez & Blanchette, var. nov. Figs 11–14.

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Fig 11. Basidiomata and rhizomorphs of Polyporus leprieurii var. yasuniensis.

A. Gregarious habit of basidiomata and primordia. B. Aged basidiomata. B.1. Pore layer. C. Freshly developed rhizomorphs D. Aged rhizomorphs emerging from coarse-woody debris. E. White rhizomorphic mat formed on new wood substrate.

https://doi.org/10.1371/journal.pone.0254567.g011

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Fig 12. Microscopical features from trama of P. leprieurii var. yasuniensis.

A. Basidia. B. Basidioles. C. Basidiospores. D-E. Cystidioles. D. Cystidioles of the ventricose. E. Thick-walled round-like cystidia cells. F. Hyphidia, 1. Dichohyphidia and 2. Tubular. G. Skeletal-binding hyphae. H. Thick-walled distinctive stalks of tramal hyphae. Scale bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g012

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Fig 13. Microscopical features from context, stipe and rhizomorphs of P. leprieurii var. yasuniensis.

A. Skeletal-binding hyphae from context, 1 Thick-walled sections and 2 Hooked-like sections of hyphae (arrows pointing to hooked sections). B. Skeletal-binding hyphae from rhizomorphs. C. Skeletal-binding hyphae from stipe D. Plectenchymatous thickenings from rhizomorphs (arrow pointing to a clamp connection). E. Melanized cuticle cells from stipe, 1 Palisade layer of cells and 2 Individual cuticle cell. Scale bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g013

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Fig 14. Cultural characteristics and microscopical features of P. leprieurii var. yasuniensis.

A. Macromorphology of colonies on MEA. B. Macromorphology of colonies on MYA. C. Slightly branched section of hyphae from white mycelium (Red Congo). D. Generative hyphae with clamp connection (Red Congo). E. Thin-walled hyphae from white sections of mycelium (Melzer’s reagent). F. Highly nucleated section of hyphae (Red Congo). Scales bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g014

Typus. Ecuador, Orellana Province, Yasuní Forest Dynamic Plot. Collected by C E Toapanta-Alban, 1 Jul 2017. Collection number: CT-16F. Found growing on dead wood of angiosperms.

Mycobank no.: MB 838030

Holotype:    Fungarium number: QCAM7764 (QCAM)

            Collection number: CT-16F, Toapanta-Alban, July 2017

            GenBank no.: (ITS: MT950148), (LSU: MT950177), (EF1-α: MW287101), (RPB1: MW287124), (SSU: MT950223).

Paratypes:    - Fungarium number: QCAM7764 (QCAM)

            Collection number: CT-16F, Toapanta-Alban, October 2019.

            - Fungarium number: QCAM7765 (QCAM)

            Collection number: CTR-1-7.2, Toapanta-Alban, January 2017

            GenBank no.: (ITS: MT95014), (LSU: MT950178), (EF1-α: MW287102), (RPB1: MW287125), (SSU: MT950224).

            - Fungarium number: QCAM7368 (QCAM)

            Collection number: CTR-2-12, Toapanta-Alban, July 2017

            GenBank no.: (ITS: MT950143), (LSU: MT950172), (EF1-α: MW287089), (RPB1: MW287115), (SSU: MT950218).

            - Fungarium number: QCAM7389 (QCAM)

            Collection number: CTR-2-33, Toapanta-Alban, July 2017

            GenBank no.: (ITS: MT950144), (LSU: MT950173), (EF1-α: MW287099), (RPB1: MW287122), (SSU: MT950219).

            - Fungarium number: QCAM7391(QCAM)

            Collection number: CTR-2-35, Toapanta-Alban, July 2017

            GenBank no.: (ITS: MT950145), (LSU: MT950174), (EF1-α: MW287097), (RPB1: MW287121), (SSU: MT950220).

Etymology: yasuniensis (Yasuní = the paradise/God’s creation (from the Wao Terero language use by the Huaorani/Waorani Indigenous People living in the Amazon Rainforest between the Napo and Curaray Rivers in Ecuador)) + ensis (Latin suffix to denote origin). In reference to the site where samples were collected, Yasuní National Park in Ecuador.

Basidiomata annual, gregarious, lateral or eccentrically stipitate, 2–5 cm tall (Fig 11).

Pilei dimidiate, flabelliform or reniform with regular to irregular margins; 1.5–6 cm in diameter and up to 1.3 mm thick. Pilear surface and texture, smooth, glabrous, flexible, coriaceous when fresh and rigid slightly shrunken when dried; yellowish to pale luteous (Munsell’s reference: 2. 4Y/8.5/7.0) when young; ochraceous, brick, sienna, umber (Munsell’s reference: 10. OR/5.6/6.5; 6. OYR/5.1/10.8; 7. Oyr/3.7/5.8) when old. Pore surface white creamy when fresh and light brown pinkish when dried. Pores circular to slightly angular, 6–10 per mm (ave = 8), 40–87 μm (ave = 66). Dissepiments entire, 45–180 μm (ave = 48) (Fig 11 B.1). Tubes concolorous with pore surface, uniform not stratified, up to 0.33 mm (ave = 0.19); IKI+. Context homogeneous, light brown, up to 0.70 mm thick; IKI-. Stipe cylindrical to slightly flat, solid, glabrous, bearing a dark cuticle, brown to reddish when young and dark brown to black when aged; up to 3 mm diameter and 0.60–4 cm long.

Hyphal system dimitic with generative and skeletal-binding hyphae. In the trama, generative hyphae, hyaline, highly branched with thin and thick-walled sections (1–4 μm), with simple septa and clamp connections (Fig 12).

Emerging from the generative hyphae, thick-walled distinctive stalks (up to 7 μm thick and 25–60 μm length) with pointing apexes somewhat rounded to sharp and up to three branches emerging from the middle to the top sections of the stalks; branches thin-walled, 1–3 μm with simple septa. Skeletal-binding hyphae found in the trama, context, stipe, and rhizomorphs (Fig 13).

In the trama and context, skeletal-binding hyphae are of the arboriform type, hyaline, highly branched, thin and thick-walled (1.5–4 μm) with simple septa. Skeletal-binding hyphae in the stipe and rhizomorphs are also of the arboriform type, somewhat less branched, hyaline, thin and thick-walled (1–5 μm) with simple septa. In context and stipe, plectenchymatous thickenings are common, 4.5–11 μm (ave = 6 μm) wide and 17–60 μm (ave = 68 μm) long. In the stipe, generative hyphae can be found holding cuticle cells, which are yellowish to brown, well compacted forming a palisade layer of cells that emerge from thinner hyphae in groups of three or more rounded and lobed cells forming a crown-like shape structure. The hymenium is composed of paraphysoids structures (cystidioles, basidioles, and hyphidia) and basidia. Hyphidia can be tubular and branched (dichohyphidia), hyaline, smooth, 2.5–6 μm (ave = 3) wide, IKI-. Cystidioles can be thick-walled round-like cells (5x5 μm) and of the ventricose type (12–19 x 5–8 μm). Basidia clavate, four-sterigmata, 18–30 μm x 6–10 μm, difficult to find. Basidioles clavate, 8–13 x 4.5–8 μm, abundant in the hymenium. Basidiospores ellipsoid to narrowly ellipsoid, slightly cylindrical, hyaline, thin-walled, smooth, IKI-, 4.5–7 μm (ave = 5.4) x 2.4–3.3 μm (ave = 2.6), Q = 1.50–2.4 (ave = 2).

Rhizomorphs, cylindrical, solid, coriaceous, thin, up to 2 mm diameter and 0.3–1 m long; bearing a black-reddish lacquered cuticle with yellow and white tips when fresh; black and rigid when dried (Fig 12). Rhizomorphs in this taxon are abundant, found in all collection sites (40), distributed on valleys (temporarily flooded forest), slopes, and ridges (terra firme forest). Can be annual to perennial as they can be present for more than four years in colonized areas from 5 m² to 20 m². Rhizomorphs emerge from fine and coarse woody debris, standing and downed dead trees. Often rhizomorphs are found attached to trees and other surfaces to maintain their upward growth. Rhizomorphs attach to new substrates and other rhizomorphs by forming a rhizomorphic mat of white mycelium that turns brown-reddish and becomes darker over time. When attached to other rhizomorphs, they form a complex rhizomorphic network covering living and dead plant material found on the forest floor. Rhizomorphs can accompany basidiomata or be alone. It is rare, but basidiomata can emerge from rhizomorphs.

Cultural characteristics: Cultures were easily obtained from rhizomorphs, basidiomata, and colonized substrate. Initial growth is characterized by white, appressed, silky to cottony mycelium that can turn dark brown to reddish. Colonies can develop crustose melanized tissue at sections or on the whole colony. Some colonies might not be melanized at all. Growth rate, characteristics of the mycelial mat, presence of aerial mycelium, and color of the colony are highly variable.

Grow rate is relatively slow on MEA 29.96–41.45 mm (ave = 33.90) compared to MYA 36.83–42.19 mm (ave = 40.28) after one month of growth (Fig 14).

On MEA, the marginal zone is irregular, usually appressed or submerged in the agar giving the appearance that aerial mycelium is absent in the margin. Aerial mycelium white, floccose, silky, cottony; thick, crustose, coriaceous, brown tissue can be formed over time. The agar can have a glossy brown discoloration and chamois-like appearance when the mycelium is submerged; pseudosclerotial plates are often formed. On MYA, margins of colonies are irregular, generally appressed, and raised near the plate’s wall. Mycelium can be submerged and aerial; when aerial, silky, floccose, cottony white-creamy with dark radial discolorations. Crustose mycelium is often formed on the melanized sections which become tough coriaceous and difficult to cut overtime. Rhizomorphs developed on culture media but only after long periods (6–12 months) of growth apparently after nutrients have been utilized (on MYA only).

Hyphal system is dimitic, with generative hyphae of the arboriform type with thin and thick-walled sections in the white-aerial mycelium and skeletal hyphae in the melanized-crustose sections of mycelium. Generative hyphae, thin-walled sections 1–2.5 μm wide and thick-walled sections 2–6 μm wide; simple septa and clamp connections; IKI-; KOH-. Skeletal hyphae from crustose sections of mycelium are yellowish-brown, similar to hyphae from the cuticle on stipe and rhizomorphs. Skeletal hyphae are arranged in clusters forming a palisade, individual cells 2–8 μm wide, thicker along branches near the melanized tissue, clamp connections abundant.

Substrate: Basidiomata and rhizomorphs emerge from decayed wood: fine and coarse woody debris, small pieces of lignified tissue from the veins of palm leaves, standing and downed dead trees. In laboratory assays, rhizomorphs can emerge from colonized wood of conifers (data not presented here).

Distribution: Known from the Amazon rainforest of Ecuador along valleys, slopes and ridges (temporary flooded and terra firme forests).

Specimens examined: Ecuador, Francisco de Orellana Province, Yasuní National Park (0° 41’ 0.5” S 76° 23’ 58.9” W). Samples collected from December 2016 to October 2019. Collection number: CT-16F, CTR-1-7.2, CTR-2-12, CTR-2-33, and CTR-2-35.

Remarks: The type specimen of P. leprieurii var. yasuniensis was collected in an area of 40 x 30 m² in terra firme forest in Yasuní National Park, Ecuador. This collection site was observed to produce rhizomorphs and basidiomata for over four years. This taxon is very common along the forest floor in terra firme and temporarily flooded forests with collection sites that vary from 0.5–40 m². P. leprieurii var. yasuniensis is characterized by annual basidiomata, lateral or eccentrically stipitate, gregarious. Pilei dimidiate, flabelliform or reniform with regular to irregular margins; thin up to 1 mm thick; coriaceous, flexible when fresh and rigid when dried. Hyphae system dimitic with generative and skeletal-binding hyphae of the arboriform type. Basidiospores ellipsoid to narrowly ellipsoid, slightly cylindrical. Cystidia-like terminal thick-walled rounded structures and abundant cystidioles accompanying basidia and the sterile hyphae in the hymenium. Rhizomorphs common, short to long, thin, flexible, coriaceous, non to highly branched, bearing a black-reddish cuticle. Neodictyopus, can be confused with P. leprieurii (Mont.) and P. leprieurii var. yasuniensis, however they differ in the color of the pilei when basidiomata are aged with white-creamy to orange hues in P. leprieurii and P. leprieurii var. yasuniensis and reddish to purplish in Neodictyopus. Macromorphologically, P. leprieurii and P. leprieurii var. yasuniensis have non variations. Microscopically, P. leprieurii (Mont.) and P. leprieurii var. yasuniensis differ in the presence of cystidioles and thick-walled stalks with pointing apex present in the trama of P. leprieurii var. yasuniensis.

7. Polyporus taromenane Toapanta-Alban, Ordoñez & Blanchette, sp. nov. Figs 15–17.

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Fig 15. Basidiome and rhizomorphs of Polyporus taromenane.

A. Basidiome and rhizomorphs on substrate A.1 Pore layer. B. Pileus. C. Stipe. D-F. Rhizomorphs. D. Fresh rhizomorph with white tip. E. Rhizomorphs with velvety appearance. F. Rhizomorphs attached to substrate and living plant material.

https://doi.org/10.1371/journal.pone.0254567.g015

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Fig 16. Microscopical features of P. taromenane.

A. Basidia (1) and basidioles (2). B. Basidiospores. C. Paraphysoids structures. C1 Cystidioles of the ventricose type and C2 Hyphidia (arrow pointing a clamp connection). D. Basidiole, cystidiole of the ventricose type and hyphidia on a generative hypha. E-F. Hyphae from trama, with E. slightly ramified sections of thin-walled hyphae and F. Section of hyphae highly nucleated and highly ramified (arrows pointing on nucleus). G. Skeletal-binding hyphae from context. G.1. Plectenchymatous thickenings from context. H. Skeletal-binding hyphae from stipe. H.1. Plectenchymatous thickenings from stipe. I. Skeletal-binding hyphae from rhizomorphs. J. Individual cuticle cells from stipe. Scale bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g016

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Fig 17. Cultural characteristics and microscopical features of P. taromenane.

A. Macromorphology of colonies on MEA. B. Macromorphology of colonies on MYA. C-D Slightly branched sections of hyphae from white mycelium with simple septa and clamp connections (Red Congo). Scales bars = 10 μm.

https://doi.org/10.1371/journal.pone.0254567.g017

Typus. Ecuador, Orellana Province, Yasuní Forest Dynamic Plot. Collected by C E Toapanta-Alban, 14 Jul 2017. Collection number: CTR-2-42. Growing on dead wood of angiosperms.

Mycobank no.: MB 838030

Holotype:    Fungarium number: QCAM7432 (QCAM)

            Collection number: CTR-2-42, Toapanta-Alban, July 2017

            GenBank no.: (ITS: MT950127), (LSU: MT950158), (EF1-α: MW287087), (RPB1: MW287113), (SSU: MT950203).

            Paratypes:    - Fungarium number: QCAM7766 (QCAM),

                        Collection number: CTR-1-8, Toapanta-Alban, January 2017

            GenBank no.: (ITS: MT950126), (LSU: MT950157), (EF1-α: MW287086), (RPB1: MW287112), (SSU: MT950202).

            - Fungarium number: QCAM7767 (QCAM),

            Collection number: CTR-3-21, December 2018

            GenBank no.: (ITS: MT950128), (EF1-α: MW287088), (RPB1: MW287114), (SSU: MT950204).

Etymology: taromenane from the Huaorani language (Wao-Terero) in reference to the voluntary isolated indigenous clan Taromenane, which are distantly related to the Huaorani people. Meaning unknown.

Basidiome is rare and only one sample was found over three years of sampling at three collection sites with rhizomorphs belonging to this taxon. Basidiome annual, solitary, centrally stipitate, 8 cm tall. Pileus infundibuliform, depressed with regular hirsute margins; 5.5 cm in diameter and 3 mm thick (Fig 15).

Pilear surface smooth, glabrous, pale luteus to amber (Munsell’s reference: 2. 4Y/8.5/7.0 and 4. OY/7.5/8.0). Pilear texture tender when fresh; shrunken and rigid when dried. Pore surface pale luteus (Munsell’s reference: 2. 4Y/8.5/7.0). Pores angular to slightly elongated, 1–2 per mm (ave = 1.5), 0.4–0.9 mm (ave = 0.66) (Fig 15 A.1). Dissepiments entire, 1–3 mm (ave = 2.3). Tubes concolorous with pore surface, not stratified 0.65–1.84 mm (ave = 1.05); IKI+ (slightly red reaction). Context homogeneous, concolorous with pore surface, 0.3–0.4 mm (ave = 0.36) thick; IKI-. Stipe cylindrical, solid, velvety with short uniform white and reddish-brown hairs, bearing a dark-brown cuticle, up to 4.5 cm long and up to 3.5 mm diameter.

Hyphal system dimitic with generative and skeletal-binding hyphae. In the trama, generative hyphae, hyaline, highly branched with thin and thick-walled sections (1–5 μm wide) with simple septa and clamp connections (Fig 16).

Skeletal-binding hyphae found in the trama, context, stipe, and rhizomorphs. In the trama and context, skeletal-binding hyphae are of the arboriform type, hyaline, highly branched, thin and thick-walled (1.5–5 μm wide) with simple septa. Skeletal-binding hyphae in the stipe and rhizomorphs are also of the arboriform type, somewhat less branched, hyaline, thin and thick-walled (1–3.8 μm wide) with simple septa. In context and stipe, plectenchymatous thickenings are common, 4–7 μm (ave = 5.33 μm) wide and 80–147 μm (ave = 90 μm) long; clamp connections observed where ramifications start. In the stipe, generative hyphae hyaline to yellowish, highly branched, thin (1–3.8 μm) and thick-walled (1–3.8 μm). Cuticle cells, which are yellowish to brown, well compacted forming a palisade layer of cells that emerge from thinner hyphae in groups of three or more round to lobed-like cells forming crown-like structure, with simple septa and clamp connections; cuticle 130 μm thick. The hymenium is composed of paraphysoids structures (cystidioles, basidioles, and hyphidia) and basidia. Hyphidia tubular to slightly branched, 3–6 μm (ave = 3) wide, IKI-. Cystidioles of the ventricose type (20–30 x 5–7 μm), rare. Basidia clavate, four-sterigmata, 14–38 μm length (ave = 27) x 5–8 μm wide (ave = 6). Basidioles clavate, 8–13 x 4.5–8 μm, abundant. Basidiospores narrowly ellipsoid to cylindrical, hyaline, smooth, thin-walled, IKI-, 7–10 μm (ave = 8) length x 3–4 μm (ave = 3.5) wide, Q 1.90–3 (ave = 2.40).

Rhizomorphs, cylindrical, solid, coriaceous, thin, up to 3 mm diameter and 2.5 m long; bearing a black-reddish cuticle with white-yellowish tips and small brown hairs; rigid when dried (Fig 15). Rhizomorphs in this taxon are long and not ramified. Rhizomorphs can be annual to perennial as they have been found growing in the same area for up to four years. Rhizomorphs emerge from decayed wood covered with a black melanized cuticle that makes the wood hard to break. Rhizomorphs are not abundant; however, they can be very long and survive longer than the rhizomorphs of P. leprieurii var. yasuniensis.

Cultural characteristics: Cultures were obtained from colonized substrate. Initial growth is characterized by white, appressed, silky to cottony mycelium that grows relatively slow compared to other fungi in the group. There are small variations regarding grow rate, characteristics of the mat, aerial mycelium and color among colonies growing on different types of media. Colonies can develop melanized tissue, however, it is spotted and appears as small dots on the colony which can be lost overtime.

Growth rate on MEA 8.23–13.13 mm (ave = 11.77) and MYA 7.1–21.31 mm (ave = 10.68) in a month of growth is relatively slow compared to other taxa examined here (Fig 17).

On MEA, the marginal zone is irregular, usually appressed or submerged in the agar giving the appearance that aerial mycelium is absent. Aerial mycelium, white to creamy, compacted, cottony at sections. On MYA, margins of colonies are irregular, generally submerged and slightly appressed. Aerial mycelium, silky, compacted, slightly floccose, white to creamy, but not melanized.

Hyphal system is monomitic, with skeletal-binding hyphae, hyaline, smooth to granular along highly nucleated sections; highly branched; thin and thick-walled (1.7–6.8 μm wide) with clamp connections and simple septa; IKI-; KOH-.

Substrate: Basidiome and rhizomorphs emerge from decay wood (coarse and fine woody debris).

Distribution: Known from the Amazon rainforest of Ecuador along ridges and slopes (terra firme and temporary flooded forests).

Specimens examined: Ecuador, Yasuní National Park (0° 41’ 0.5” S 76° 23’ 58.9” W), Francisco de Orellana Province, samples collected from December 2016 to October 2019. Collection number: CTR-1-8 (rhizomorphs and cultural characteristics), CTR-2-42 (rhizomorphs and Basidiome), CTR-3-21 (rhizomorphs).

Remarks: The type specimen of P. taromenane was described from a single basidiome collected in October 2019 in an area of 0.5 m² in terra firme forest in Yasuní National Park. The collection site produced rhizomorphs over four years, but only one basidiome was found within that time period. This taxon is somewhat rare compared to P. leprieurii var. yasuniensis, with only three collections within the 50-ha study site. P. taromenane is characterized by annual basidiomata, central, stipitate, solitary. Pileus circular, infundibuliform, depressed with regular hirsute margins. Big angular to slightly elongated pores. Hyphal system dimitic with generative and skeletal-binding hyphae of the arboriform type. Skeletal-binding hyphae in context and stipe with plectenchymatous thickenings. Basidiospores narrowly ellipsoid to cylindrical. Sterile structures present in the hymenium: ventricose cystidioles are rare; hyphidia common; basidioles clavate, abundant. Rhizomorphs circular, solid, robust, long, somewhat not branched, flexible, coriaceous, bearing a black-reddish cuticle and small brown hairs. P. taromenane is closely related to P. guianensis Mont., with this, it shares macromorphological similarities in terms of, pilei color and texture, color and texture of the stipe, pore’s shape and size. Micromorphological differences with P. guianensis, include the presence of sterile elements in the hymenium and presence of plectenchymatous thickenings in the skeletal-binding hyphae in the context and stipe. There are no reports of rhizomorph development in P. guianensis, which have most reports in Tropical Asia.