Wentiomyces sp . from plant litter on poor fen in northeastern Poland

The results of the extensive literature survey published by Thormann and Rice [1] have shown that more than 600 species of fungi were already recorded from various types of peatland habitats. Peatlands are one of the major carbon-sequestrating ecosystems (e.g. [2]), and the apparent negative influence of various anthropogenic disturbances, e.g. global warming and water-level drawdown on decomposition processes, has stimulated research on many interconnected ecological aspects, including interactions with microbial decomposers, and especially fungi (e.g. [3]). ORIGINAL RESEARCH PAPER Acta Mycol 49(2):237–247 DOI: 10.5586/am.2014.021 Received: 2014-04-15 Accepted: 2014-10-14 Published electronically: 2014-12-01


Introduction
The results of the extensive literature survey published by Thormann and Rice [1] have shown that more than 600 species of fungi were already recorded from various types of peatland habitats.Peatlands are one of the major carbon-sequestrating ecosystems (e.g.[2]), and the apparent negative influence of various anthropogenic disturbances, e.g.global warming and water-level drawdown on decomposition processes, has stimulated research on many interconnected ecological aspects, including interactions with microbial decomposers, and especially fungi (e.g.[3]).
Fungi are described to be the most important group of decomposers in these ecosystems [4,5], and growing interest regarding different aspects of fungal diversity and role on peatlands can be observed (e.g.[6,7]).However, still surprisingly few of those studies concern the diversity and potential role of the leaf-litter microfungal communities (e.g.[8]).Our knowledge and understanding of the factors involved in the decomposition processes on peatlands and the possible interactions of these with climate change and anthropogenic disturbances are therefore incomplete without more research on peatland mycobiota.
During our research on leaf-litter microfungi from peatlands, interesting specimens were found, which were identified as Wentiomyces sp.The concept of this genus is still little understood, therefore the aim of this paper was to provide some details concerning our findings and review the current knowledge regarding the taxonomy and biology of the genus Wentiomyces.

Material and methods
Findings described in this paper originate from a research project carried in 2010-2014 on peatlands in the Szeroki Bór mire complex, near town of Pisz, the Warmińsko-Mazurskie Voivodeship, northeastern Poland.The study site, where the presented fungal specimens were found, was located on open poor fen, being in fact a small lake completely overgrown by dense cover of Sphagnum spp. with Carex limosa L., Eriophorum vaginatum L., Vaccinium oxycoccos L. and Drosera rotundifolia L.; dead pine trees occur on the banks.The material collected in October 2010 for preliminary screening, comprised of mixed litter of moribund and healthy Sphagnum spp.fragments with addition of dead leaves and stems of Vaccinium oxycoccos.
The method of incubation of plant litter samples in damp chambers was employed for the study [9].Material was observed under dissecting microscope SMZ800, and semipermanent prep-slides were made in lactophenol-blue or glycerin, and observed under Nikon Eclipse E200 light microscope.All prep-slides and photographs are housed in the mycological laboratory of the Department of Plant Systematics and Geography, Faculty of Biology, The University of Warsaw.Taxonomic system and nomenclature for fungi follow MycoBank [10], and for plants follow Integrated Taxonomic Information System [11] except for the table, where they are given as in original publications.

Discussion
Despite of more than a century since its discovery, the taxonomy of the genus Wentiomyces remains extremely complicated.It was raised by Koorders [12], to encompass a single species, W. javanicus Koord., characterized by superficial, hypophyllous mycelium with superficial pseudothecia (perithecia in original description) possessing in the upper part characteristic, melanized, dichotomously branched at the apex setae, and on the lower part of the ascomata brownish, long hair-like hyphal appendages (although called setae in the original description); asci clavate with eight ascospores; ascospores hyaline, with median septa; no paraphyses.Koorders himself mentions, however, that his material is sparse, and mostly immature, and that the color of mature ascospores could potentially change to brownish, although he states this was unlikely [12].The original herbarium material of the type is unavailable [13,14], and this is the cause for several taxonomical rearrangements of this genus, of which none can still be considered final, because epitypification was never conducted.Hansford [15] first mentioned the possible synonymy of the Wentiomyces and Dimeriella Speg., but it was Müller and Arx [13], who finally concluded that these two genera are in fact synonymous, and have given the name Wentiomyces priority over Dimeriella, and eleven other generic names considered synonymous.It has to be noted, that in their understanding of the genus, the shape of the setae was no longer considered specific, therefore Wentiomyces fide Müller and Arx [13] included also species with simple, acute or blunt setae; in addition some taxa included have sparse paraphysoids.Farr [16] however claimed Wentiomyces to be a doubtful genus, which should not be used in favor of Dimeriella.This was further applied and expanded by Barr [17], who rejected Wentiomyces, and transferred six species (including two subspecies) with dichotomously branched setae to Neocoleroa Petrak, and one lichenicolous species with straight, acute setae to Raciborskiomyces Siemaszko.To further complicate the situation, this rearrangement is not widely and uniformly accepted.In addition, Etayo and Sancho [18], transferred two lichenicolous taxa with straight setae to Niesslia Auersw.Because of this chaos, it is even difficult to estimate the correct number of the species included in Wentiomyces.After their treatment from 1962 [13], Arx and Müller [19] concluded that Wentiomyces contains "about 50 species", the large number being of course due to synonimization of Dimeriella with Wentiomyces, and this was later adopted by Kirk et al. [20].
Search in Index Fungorum database [21], however, brings only 21 records, with 20 species and two subspecies.Of these, Wentiomyces fuliginosus (Woron.)E. Müll. is treated as a synonym of Antenulariella fuliginosa Woron., Wentiomyces hirtulus (Speg.)E. Müll.as a synonym of Dimeriella hirtula Speg., and Wentiomyces peltigericola D. Hawksw.as a synonym of Niesslia peltigericola (D.Hawksw.)Etayo.Search in the MycoBank database [10] brings the same number of results, but without clear statements on the status of the abovementioned three species, suggesting 20 existing species for Wentiomyces.That is due to the fact, that no formal combinations were created for the vast majority of Dimeriella species to be included in Wentiomyces, even in the abovementioned studies by Müller and Arx [13], and Arx and Müller [19].
This situation clearly indicates that the genus Wentiomyces is in urgent need for revision, and the chaos here is corroborated by the fact, that there are no molecular sequences of any of the described species [22].It is also worth noting, that the names Wentiomyces and Dimeriella are on the preliminary draft of the list of protected generic names for fungi [23], and therefore the taxonomic and phylogenetic relationships between and within them will have to be resolved.
If the MycoBank classification system is adopted, the genus Wentiomyces comprises species, which grow as saprotrophs and/or biotrophs on plants, and as specialized lichenicolous fungi (Tab.1).Most plant-associated taxa grow hypophyllously, with only few recorded also from plant stems.Some authors label Wentiomyces spp. as pathogens, causing leaf spot diseases ( [24] for W. javanicus).It appears, that some taxa can also penetrate leaf cuticle [e.g.W. clavisetus (Doidge) Arx] [15]; in case of lichenicolous taxa, Hansford [25] mentions that W. lichenicola (Hansf.)D. Hawksw.penetrates the thallus of a lichen.Lichenicolous species occur on terrestrial lichens (W.peltigericola on Peltigera spp.), but also on epiphyllous lichens (W.lichenicola on Fellhanera and Bacidina).According to the USDA fungus-host database [26], there are 38 published reports on 14 species of Wentiomyces from 16 countries; half of the reports are from tropical countries; these are however incomplete data, because many other reports, especially for lichenicolous species, exist (Tab.1).There is a recent finding of Wentiomyces sp. from Poland [27] on dead leaves of Rhododendron tomentosum Harmaja from poor fen.We know also on the findings on other Ericaceae from raised bog in Siberia (N.V. Filippova, personal (A) [13,15]; (B) [26];

Species
(C-E) [33] W. clusiae J.L.There is an interesting suggestion about possible anamorph genus drawn by de Hoog et al. [28], who have examined a herbarium material of W. javanicus deposited by Joly [29].Joly [29] depicted anamorphic fungus, which he had isolated in pure culture from ascospores of his specimen of W. javanicus; de Hoog et al. [28] noted the resemblance of this anamorph to Rhinocladiella anceps (Sacc.& Ellis) S. Hughes (recalled also by Arzanlou et al. [30]).Unequivocal link between these two morphs was however not demonstrated; moreover, according to molecular analyses species from the genus Rhinocladiella and similar Ramichloridium are placed predominantly within Chaetothyriales and Capnodiales, with possible teleomorphs for Rhinocladiella in Capronia spp.[30,31].
Our specimens could not be identified to the species level, because we have not observed asci and ascospores, and the sole gross morphology of pseudothecia and setae, or host species, do not provide firm characters.Wentiomyces oreophilus (Speg.)E. Müll.described from Rhododendron ferrugineum L. has straight setae, and therefore cannot be considered conspecific with our finding (as was incorrectly assumed by Wilk et al. [27] regarding another specimen from poor fen).Wentiomyces sibiricus (Petr.)E. Müll., described from Vaccinium myrtillus L. could be one possibility.Worth noting is the fact, that the specimens presented here differ greatly from the specimen presented by Wilk et al. [27], being in all respects smaller (42-50 μm versus 87.5-170 μm) and having less ramified setae.We cannot even state for sure, that both specimens reported here represent the same or different species, and therefore further research aimed specifically at habitat-and host-preferences of non-lichenicolous Wentiomyces spp. is certainly needed.