Pyrenidium
Pyrenidium Nyl., Flora, Regensburg 48: 210 (1865).
Index Fungorum number: IF 4578; Facesoffungi number: FoF 07909, 13 morphological species (Species Fungorum 2022), 3 species with molecular data.
Lichenicolous, parasitic, non-lichenized. Sexual morph: Ascomata peritecioid pseudothecia, subglobose, ovoid or obpyriform, dark brown or black, ostiolate, immersed, semi-immersed or subsessile, scattered or in smalls groups, sometimes confluent in necrotic patches or in gall-like deformations of the host thallus. Ascomatal wall entirely brown to dark brown, frequently with green tonality near the ostiolar zone, pseudoparenchymatous, composed of several layers of isodiametric to tangentially elongated cells, with brown pigmented cell wall. Hamathecium in the mature perithecia formed by paraphysoids and periphyses, hyaline, I-, K/I-. Paraphysoids well developed, numerous, remaining distinct, filiformes, hyaline, septate, abundantly branched and anastomosed. Periphyses ostiolar filaments clearly differentiated, branched, hyaline, in some species green pigmented at the top of the ostiolar region. Asci clavate to subcylindrical, distinctly stipitate, bitunicate (fissitunicate), thickened with a distinct internal apical beak at the apex, I-, (2-)4- or 8-spored. Ascospores brown or dark brown in the oldest, with the tips of the end cells often pale brown to subhyaline, ellipsoid to broadly fusiform, often slightly curved, rounded or obtuse at the apices, usually 3-septate, rarely 2- or 4-septate. In some species some extra, small, uniseptate spores can be found in the asci; usually with a conspicuous pore at the central part of the septa, constricted at the septa or not; smooth-walled. Asexual morph: Conidiomata pycnidial, black, immersed, with a dark brown wall. Conidia hyaline, simple, short-oblong (adapted from Navarro-Rosinés & Roux 2007).
Type species: Pyrenidium actinellum Nyl.
Notes: Species of Pyrenidium are lichenicolous and characterised by subglobose, ovoid or obpyriform, dark brown or black ascomata, confluent in necrotic patches, entirely brown to dark brown peridium, clavate to subcylindrical asci and pale brown to subhyaline, ellipsoid to broadly fusiform ascospores. Pyrenidium actinellum was reported from Leptogium teretiusculum sensu lato in England and described as a subfruticose, cyanophilous lichen (Navarro-Rosinés & Roux 2007, Knudsen & Kocourková 2010). Zahlbruckner in Engler (1898) introduced Pyrenidiaceae to accommodate Pyrenidium. Hawksworth (1983) discussed the history of Pyrenidium. Crivelli (1983) reported that Pyrenidium resembles Dacampia in having similar ascomatal arrangements and wall tissues but this has not been confirmed with molecular data. Pyrenidiaceae was synonymized to Dacampiaceae since Pyrenidium is morphologically similar to Dacampia (Hawksworth 1980, Lumbsch & Huhndorf 2010, Hyde et al. 2013, Wijayawardene et al. 2014, 2018, Jaklitsch et al. 2016). Navarro-Rosinés and Roux (2007) re-circumscribed the genus and excluded Pyrenidium hyalosporum from Pyrenidium based on the hyaline ascospores. Several authors accepted Pyrenidium in Dacampiaceae based on morphology (Lumbsch & Huhndorf 2010, Hyde et al. 2013, Wijayawardene et al. 2014, 2018, Jaklitsch et al. 2016). Hyde et al. (2013) placed Pyrenidium in Dacampiaceae based on the 3-septate ascospores, wall at each end paler and thinner and lichenicolous ascomata. Navarro-Rosinés and Roux (2015) provided an updated account of Pyrenidium. Doilom et al. (2018) re-examined the lectotype of P. actinellum (H-NYL 41028) and accepted Pyrenidium in Dacampiaceae. Huanraluek et al. (2019) sequenced five freshly collected specimens of Pyrenidium and showed that Pyrenidium is distantly related to Dacampiaceae based on the phylogenetic analyses from nuLSU and nuSSU sequence data. Huanraluek et al. (2019) resurrected Pyrenidiaceae to accommodate Pyrenidium. Huanraluek et al. (2019) also excluded P. hyalosporum based on the occurrence on Phacopsis gelida, hyaline ascospores and in lacking a central pore in the ascospore septa, features which are atypical of other species of Pyrenidium. Pyrenidium actinellum is characterised by perithecioid ascomata with a bluish green hue which could not be observed by Doilom et al. (2018) and Huanraluek et al. (2019). Huanraluek et al. (2019) also mentioned that P. hyalosporum lacks periphyses in the hamathecium, has 2-septate ascospores measuring over 30 µm, which is greater than the spore size of any other species included in Pyrenidium. Pyrenidium actinellun sensu lato comprises a group of species that differ in the form and size of ascospores, size and features of the ascomata, and nature of the host (Navarro-Rosinés & Roux 2015). Pyrenidium actinellun in its strict sense is restricted to lichenicolous fungi that occur on Leptogium teretiusculum, and is characterised by the sessile ascomata developing on the host thallus (Huanraluek et al. 2019). Huanraluek et al. (2019) did not provide any ordinal rank for Pyrenidiaceae. Pyrenidium is a distinct genus in Pyrenidiaceae but more collections with DNA sequence data are needed to elucidate its phylogenetic placement. Molecular markers available for Pyrenidium include P. borbonicum (LSU, SSU), P. aff. aggregatum (LSU, SSU) and P. cf. actinellum (LSU, SSU).
Recent News
Recent paper to be publishedRecent Genus
NothocladosporiumPhillipsiella
Curreya
Recent Species
Nothocladosporium syzygiiPhillipsiella atra
Curreya conorum
