Research Article |
Corresponding author: Giovanni Sicoli ( giovanni.sicoli@unical.it ) Academic editor: Bryn Dentinger
© 2019 Giovanni Sicoli, Nicodemo G. Passalacqua, Antonio B. De Giuseppe, Anna Maria Palermo, Giuseppe Pellegrino.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Sicoli G, Passalacqua NG, De Giuseppe AB, Palermo AM, Pellegrino G (2019) A new species of Psathyrella (Psathyrellaceae, Agaricales) from Italy. MycoKeys 52: 89-102. https://doi.org/10.3897/mycokeys.52.31415
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Sporophores of a new Psathyrella species have been reported for the first time as growing at the base of Cladium mariscus culms in the Botanical Garden of the University of Calabria, Rende, Cosenza, southern Italy. The fungus was initially identified as P. thujina (= P. almerensis) by means of both ecology and macro- and microscopic characteristics of the basidiomes, then referred to P. cladii-marisci sp. nov. after extraction, amplification, purification and analysis of the rDNA ITS region. We came to this conclusion after comparing our specimen with the descriptions of the taxa available in the literature for the genus Psathyrella.
Agaricomycetes, Basidiomycota, Fen-sedge, Marshes, southern Italy, Taxonomy
Within the cosmopolitan fungal genus Psathyrella (Fr.) Quél. (Agaricales, Psathyrellaceae), about one hundred species have traditionally been recognised in Europe, almost all saprotrophs and found in many and diverse environments. Either terrestrial or lignicolous, they grow mainly on organic debris from various origins, such as dung, post-fire locations and dead stems of larger herbaceous plants (
During an investigation on the mycoflora of the Botanical Garden at the University of Calabria (Rende, Cosenza, Italy), basidiomes of an apparently “psathyrelloid” fungus were detected at the base of a fen-sedge [Cladium mariscus (L.) Pohl (Cyperaceae)], a cosmopolitan-distributed plant species (Lansdown et al. 2018) occurring in marshy places of most Italian regions (
Based on records reported by
The aim of this work was therefore to identify our basidiomes by using both morpho-ecological and biomolecular tools. This was highly encouraged by the habitat peculiarity and the close relationship with a plant species with which no species of Psathyrellaceae had ever been found associated.
Eight basidiomes of the above “psathyrelloid” fungus were observed and collected on 10 April 2018, as gregarious all around and at the base of Cladium mariscus cut culms (Fig.
The basidiomes were first macroscopically examined for features, colours, sizes, hymenophore shape, pileus and stipe ornamentations, smell and taste. Then, the structures of the basidiome were microscopically inspected for cheilo- and pleurocystidia occurrence and features, presence of clamp connections, basidia and spore features. These observations were carried out under a light microscope (Axioplan 2 Imaging Microscope, Carl Zeiss, Germany) at 400 and 1,000 magnifications on fragments of pileipellis and gills placed on slides in 10% NH4OH. The results were compared with those published in the morphological keys for the Psathyrella species and, more specifically, with those species reported as the closest, according to morphology and ecological site conditions, i.e. P. thujina, P. typhae and P. lutensis (
One of the basidiomes was dehydrated at room temperature and destroyed for molecular analysis: DNA extraction, amplification, purification and sequencing of the nuc rDNA internal transcribed spacer region (ITS). DNA extraction was implemented by using CTAB protocol (Doyle and Doyle 1987) and the ITS region was amplified using the primer combination ITS1F/ITS4 (
Forward and reverse DNA fragment electropherograms were checked by means of the CHROMAS 2.6.5 software (technelysium.com.au) for a complete reconstruction of the ITS1, ITS2 and 5.8 gene fragments. Ambiguous regions at the start and the end of the alignment were deleted and gaps were manually adjusted to optimise the alignment. The sequence generated for this study is deposited in GenBank with the code MK080112.
Consensus sequences were generated from both forward and reverse primer reads in the BioEdit sequence alignment editor, version 7.2.5 (
The macro- and micro-morphological features of the basidiomes collected at the base of the fen-sedge plant in the Botanical Garden are shown in Figures
Macro-morphological characteristics of the Psathyrella basidiomes: scales of velar origin on pilei tops and margins, and beige-coloured gills (A); cylindrical, white and exannulate stems under a lateral profile (B); colour-shading of a cap hygrophany and fibrillose details of velar-originated scales (C); gills turning brown-purplish with spore maturation and a fibrillose surface of a stem base (D); a pruinose stem apex bearing a mature hymenophore with white gill edge lines (E).
Micro-morphological characteristics of the Psathyrella mycelium: clavate and sphaeropedunculate (A), and cylindric (B, C) cells at a gill edge; differently clavate (D, E) and utriform (F) cheilocystidia; variously utriform-shaped pleurocystidia (G, H, I); a fibulate hypha (J); a 4-spored basidium (K); basidiospores (L).
If we compare the morphological features of our specimens with those belonging to the closest Psathyrella species, a number of differences emerge (Table
Main differences between our Psathyrella sp. and the closest species, according to the morphological characteristics of basidiomes and mycelium, and ecology. (Differences from our specimen are in bold characters).
Morpho-ecological characteristics | Psathyrella sp. | P. thujina | P. typhae | P. lutensis |
Pileus diameter (cm) | 3.5 | 2.5 | 2.5 | 4.0 |
Pileus colour | Hazelnut brown, then beige brown | Warm brown, then beige brown | Pinkish-ochre brown, then pale flesh brown | Dark reddish brown, then very pale brown |
Stem colour | White with a pruinose apex | White with a pruinose apex | Whitish to pale brown | White with a pruinose apex, brownish base |
Spore size (µm) | 7.2–11.8 x 4.3–6.0 | 9.0–11.5 x 4.5–6.5 | 7.5–11.5(12.0) x 5.5–8.0 | 9.0–10.0 x 4.5–5.5 |
Cheilocystidia | Versiform, chiefly utriform | Utriform | Versiform, chiefly utriform | Versiform, chiefly utriform |
Pleurocystidia | Utriform | Utriform | Absent | Versiform, chiefly utriform to ventricose |
Mucoid deposits on cystidia | NO | NO | NO | YES |
Habitat | Marshes, on cut culms of Cladium | Marshes, on cut culms of Typha, Phragmites, Cirsium, Epilobium | Marshes, on cut culms of Typha, Epilobium, Scirpus, Phragmites, Rumex, Iris | Deciduous forests, on sticks in mud |
Seasonal occurrence | Spring | Autumn to winter | Summer | Summer to autumn |
As for ecology, the plant genus Cladium Browne has never been reported as a substrate to any other Psathyrella, although P. thujina and P. typhae are commonly found on the remnants of ecologically similar plants (
The obtained nrDNA sequence was 702 bp long. By comparing it with those published in GenBank, we obtained a data matrix composed of 44 taxa and 710 characters, 276 gap-free sites and 240 conserved sites. The highest homology (99%) was observed with P. candolleana (Fr.) Maire, which was confirmed by the phylogenetic analysis (Fig.
Species used for the phylogenetic analyses including GenBank Accession Numbers and published references.
Species | GenBank accession No. | Reference |
Psathyrella abieticola | KC992891 |
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P. almerensis | KC992874 |
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P. almerensis | KC992873 |
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P. ammophila | KC992872 |
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P. candolleana | AB306311 |
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P. candolleana | DQ389720 |
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P. candolleana | MG734719 |
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P. candolleana | MG734720 |
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P. cladii-marisci | MK080112 | This study |
P. conferta | KC992890 |
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P. conica | MG734713 |
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P. flexispora | MF966494 |
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P. fusca | MF966503 |
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P. impexa | KC992900 |
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P. kellermanii | KC992920 |
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P. luteopallida | MG734736 |
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P. lutensis | MG734748 |
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P. lutensis | DQ389685 |
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P. lutulenta | KC992875 |
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P. madida | KC992932 |
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P. parva | KC992912 |
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P. prona | KJ939634 |
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P. pseudogracilis | KC992853 |
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P. purpureobadia | NR_119670 |
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P. romagnesii | DQ389716 |
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P. saponacea | MH155965 |
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P. senex | MG734732 |
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P. singeri | MG734718 |
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P. squamosa | KC992939 |
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P. squamosa | MG367206 |
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P. subsingeri | MG734714 |
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P. sulcatotuberculosa | KJ138423 |
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P. tenera | FJ899635 |
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P. tenuicula | DQ389706 |
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P. thujina | KC992873 |
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P. thujina | KC992874 |
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P. thujina | KY680791 |
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P. thujina | KY680792 |
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P. trinitatensis | KC992882 |
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P. tuberculata | MH497604 |
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P. typhae | DQ389721 |
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Coprinellus heterothrix | FM878018 |
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C. impatiens | FM163177 |
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C. silvaticus | KC992943 |
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Based on results from both morphological and molecular analysis, our collection cannot be assigned to a known species. According to morphology, our Psathyrella should be closer to P. thujina (Section Spadiceogriseae). By contrast, the DNA ITS sequence would undoubtedly include it in the “candolleana” clade, where each species showed up to a 99% ITS sequence similarity with our sample. The most widespread and known species in this clade, P. candolleana and P. leucotephra (Berk. & Broome) P.D. Orton, both commonly occurring in Europe, too, are however morphologically very different from our specimen, by forming large pilei (diameter up to 8.0 cm) and lacking pleurocystidia; furthermore, the latter frequently even shows a torn annulus in the upper part of the stem, which we did not observe in our Psathyrella (
Therefore, within this framework, the placement of our fungus into the “candolleana” clade, together with other species showing strong differences for geographic and ecologic reasons, should not prevent the recognition of a new Psathyrella species.
Anyhow, more and more scientific contributions are remarking that the genetic analysis of a fungus aiming at taxonomic purposes can alone generate artefacts, i.e. “false positive” or “chimeras”, especially when such analysis is implemented by using a unique gene (
On the basis of the outcomes deriving from the morphologic, ecologic and biomolecular characteristics which we have identified in this note, we are therefore inclined to establish a new species of Psathyrella.
The specific epithet derives from Cladium mariscus, the name of the plant where it was first detected.
Similar to P. thujina from which it differs by showing a larger pileus (about 40% larger), a wider range of spore length, versiform cheilocystidia and basidiomes occurring in spring.
Italy. Calabria, Cosenza, Rende, Orto Botanico Università della Calabria. 39°21'25.05"N, 16°13'44.57"E, 220 m a.s.l., marsh at the base of cut culms of a Cladium mariscus (L.) Pohl plant, transplanted from Lago dell’Aquila (Laureana di Borrello, Reggio Calabria, southern Italy) at the corner of a concrete tank maintained full of water, 10 April 2018, Antonio Biagio De Giuseppe & Giovanni Sicoli (CLU F302).
Habit psathyrelloid. Pileus up to 3.5 cm diam., conical-convex when young, hemispheric to applanate at maturity, with a deeply striate margin, hazelnut in colour, turning to pale beige when dry. Pileipellis with evident concentric arachnoid fibrils of velar origin, whitish and easily removable, often exceeding the cuticle margin. Lamellae distant, ventricose, adnate, intermingled with numerous lamellulae, initially pale pink, then intensely brown-purplish. Lamella edge whitish with numerous sphaeropedunculate cells. Stipe, very fragile, cylindrical, white, exannulate with a diffuse fibrillosity especially on the basal surface, apical surface pruinose. Basidiospores 7.2–11.8 × 4.3–6.0 µm (n = 100), ellipsoid to ovoid-ellipsoid, with a thick and smooth wall, adaxially flattened with a central 2µm-wide germ pore and a distinct hilar appendix. Spore-print dark brown. Basidia clavate, 4-spored. Cheilocystidia versiform, often utriform, seldom cylindrical to clavate. Pleurocystidia utriform-shaped. Mycelium septate and clamped. Context with apparently no smell, taste mild.
In small groups (gregarious), on the culm remnants of Cladium mariscus. So far, known only from the type locality.
This probably rare and, apparently, never before detected species could occur more commonly if further surveys confirmed a sort of preference for C. mariscus as a growing substrate for the fungus. This plant was observed all over Italy (
We are very grateful to Pasquale A. Cicirelli and Nicola Fico for their precious advice in the digital image processing.