PhialophorasectionCatenulataedisassembled: New genera, species, and combinations and a new family encompassing taxa with cleistothecial ascomata and phialidic asexual states

Mr. Toad's Wild Fungi: Fungal Isolate Diversity on Colorado Boreal Toads and their Capacity for Pathogen Inhibition

The amphibian skin pathogen Batrachochytrium dendrobatidis (Bd) has caused an ongoing biodiversity crisis, including in the locally endangered Colorado boreal toad (Anaxyrus boreas boreas). Although researchers have investigated the bacteria living on amphibian skin and how they interact with Bd, there is less information about fungal community members. This study describes (1) the diversity of culturable fungi from boreal toad skin, (2) which subset of these isolates is Bd-inhibitory, and (3) how Bd affects these isolates' growth and morphology. Most isolates were from the orders Capnodiales, Helotiales, and Pleosporales. Of 16 isolates tested for Bd-inhibition, two from the genus Neobulgaria and three from Pseudeurotium inhibited Bd. Fungal growth in co-culture with Bd varied with weak statistical support for Neobulgaria sp. (isolate BTF_36) and cf Psychrophila (isolate BTF_60) (p-values = 0.076 and 0.092, respectively). Fungal morphology remained unchanged in co-culture with Bd, however, these results could be attributed to low replication per isolate. Nonetheless, two fungal isolates' growth may have been affected by Bd, implying that fungal growth changes in Bd co-culture could be a variable worth measuring in the future (with higher replication). These findings add to the sparse but growing literature on amphibian-associated fungi and suggest further study may uncover the relevance of fungi to amphibian health and Bd infection.

Apothecial Ancestry, Evolution, and Re-Evolution in Thelebolales (Leotiomycetes, Fungi)

Simple Summary

Leotiomycetes is one of the most speciose classes of the phylum Ascomycota (Fungi). Its species are mainly apothecioid, paraphysate, and possess active ascospore discharge. Thelebolales are a distinctive order of the Leotiomycetes class whose members have mostly closed ascomata, evanescent asci, and thus passively dispersed ascospores. Within the order, a great diversity of peridia have evolved as adaptations to different dispersal strategies. The genus Thelebolus is an exceptional case of ascomatal evolution within the order. Its species are the most diverse in functional traits, encompassing species with closed ascomata and evanescent asci, and species with open ascomata, active ascospore discharge, and paraphyses. Open ascomata were previously suggested as the ancestral state in the genus, these ascomata depend on mammals and birds as dispersal agents. In our work, we used morphological and phylogenetic methods, as well as the reconstruction of ancestral traits for ascomatal type, asci dehiscence, the presence or absence of paraphyses, and ascospore features to explore evolution within Thelebolales. We demonstrate the apothecial ancestry in Thelebolales and propose a new hypothesis about the evolution of the open ascomata in Thelebolus involving a process of re-evolution where the active dispersal of ascospores appears independently twice within the order. A new family, Holwayaceae, is proposed within Thelebolales, comprising three genera: Holwaya, Patinella, and Ramgea.

Abstract

Closed cleistothecia-like ascomata have repeatedly evolved in non-related perithecioid and apothecioid lineages of lichenized and non-lichenized Ascomycota. The evolution of a closed, darkly pigmented ascoma that protects asci and ascospores is conceived as either an adaptation to harsh environmental conditions or a specialized dispersal strategy. Species with closed ascomata have mostly lost sterile hymenial elements (paraphyses) and the capacity to actively discharge ascospores. The class Leotiomycetes, one of the most speciose classes of Ascomycota, is mainly apothecioid, paraphysate, and possesses active ascospore discharge. Lineages with closed ascomata, and their morphological variants, have evolved independently in several families, such as Erysiphaceae, Myxotrichaceae, Rutstroemiaceae, etc. Thelebolales is a distinctive order in the Leotiomycetes class. It has two widespread families (Thelebolaceae, Pseudeurotiaceae) with mostly closed ascomata, evanescent asci, and thus passively dispersed ascospores. Within the order, closed ascomata dominate and a great diversity of peridia have evolved as adaptations to different dispersal strategies. The type genus, Thelebolus, is an exceptional case of ascomatal evolution within the order. Its species are the most diverse in functional traits, encompassing species with closed ascomata and evanescent asci, and species with open ascomata, active ascospore discharge, and paraphyses. Open ascomata were previously suggested as the ancestral state in the genus, these ascomata depend on mammals and birds as dispersal agents. In this scheme, species with closed ascomata, a lack of paraphyses, and passive ascospore discharge exhibit derived traits that evolved in adaptation to cold ecosystems. Here, we used morphological and phylogenetic methods, as well as the reconstruction of ancestral traits for ascomatal type, asci dehiscence, the presence or absence of paraphyses, and ascospore features to explore evolution within Thelebolales. We demonstrate the apothecial ancestry in Thelebolales and propose a new hypothesis about the evolution of the open ascomata in Thelebolus, involving a process of re-evolution where the active dispersal of ascospores appears independently twice within the order. We propose a new family, Holwayaceae, within Thelebolales, that retains the phenotypic features exhibited by species of Thelebolus, i.e., pigmented capitate paraphyses and active asci discharge with an opening limitation ring.

Inopinatum lactosum gen. & comb. nov., the first yeast-like fungus in Leotiomycetes

Sporobolomyces lactosus is a pink yeast-like fungus that is not congeneric with other members of Sporobolomyces (Basidiomycota, Microbotryomycetes, Sporidiobolales). During our ongoing studies of pink yeasts we determined that S. lactosus was most closely related to Pseudeurotium zonatum (Ascomycota, Leotiomycetes, Thelebolales). A molecular phylogenetic analysis using sequences of the ITS region and the small and large subunit (SSU, LSU) rRNA genes, indicated that four isolates of S. lactosus, including three ex-type isolates, were placed in Thelebolales with maximum support. A new genus is proposed to accommodate S. lactosus, Inopinatum. This is the first pink yeast reported in Leotiomycetes.

Tricladiaceae fam. nov. (Helotiales, Leotiomycetes)

To resolve the polyphyletic nature of Solenopeziaceae as it was originally circumscribed, we establish a new family Tricladiaceae for those genera originally placed in Solenopeziaceae that have aquatic hyphomycete-like asexual morphs and/or a sexual morph with glabrous apothecia. These include Cudoniella, Geniculospora, Graddonia, Halenospora, Mycofalcella, Spirosphaera, and Tricladium. Solenopeziaceae is confined to the genera Lasiobelonium, Solenopezia, Trichopeziza, and Trichopezizella, all of which have a sexual morph having apothecia with smooth-walled hairs. This taxonomy is supported by a multi-gene analysis using up to 15 genes, with a few of the taxa placed on the basis of a separate ITS phylogeny. Tricladiaceae forms a monophyletic clade with a basal sister relationship to Pleuroascaceae plus Helotiaceae; Solenopeziaceae forms a monophyletic clade with a basal sister relationship to Lachnaceae.

New insights into the systematics of Bactrodesmium and its allies and introducing new genera, species and morphological patterns in the Pleurotheciales and Savoryellales (Sordariomycetes)

The newly discovered systematic placement of Bactrodesmium abruptum, the lectotype species of the genus, prompted a re-evaluation of the traditionally broadly conceived genus Bactrodesmium. Fresh material, axenic cultures and new DNA sequence data of five gene regions of six species, i.e. B. abruptum, B. diversum, B. leptopus, B. obovatum, B. pallidum and B. spilomeum, were studied. Bactrodesmium is a strongly resolved lineage in the Savoryellales (Sordariomycetes), supported by Bayesian and Maximum Likelihood methods. The genus Bactrodesmium is emended and delimited to hyphomycetes characterised by sporodochial conidiomata, mononematous often fasciculate conidiophores, holoblastic conidiogenesis and acrogenous, solitary, dry, pigmented, transversely or rarely longitudinally septate conidia. The conidia are seceding rhexolytically, exhibiting multiple secession patterns. An identification key to 35 species accepted in Bactrodesmium is given, providing the most important diagnostic characters. Novel DNA sequence data of B. longisporum and B. stilboideum confirmed their placement in the Sclerococcales (Eurotiomycetes). For other Bactrodesmium, molecular data are available for B. cubense and B. gabretae, which position them in the Dothideomycetes and Leotiomycetes, respectively. All four species are excluded from Bactrodesmium and segregated into new genera, Aphanodesmium, Gamsomyces and Kaseifertia. Classification of 20 other species and varieties not recognised in the genus is discussed. Based on new collections of Dematiosporium aquaticum, the type species of Dematiosporium, the genus is emended to accommodate monodictys-like freshwater lignicolous fungi of the Savoryellales characterised by effuse colonies, holoblastic conidiogenous cells and dictyosporous, pigmented conidia with a pore in each cell. Study of additional new collections, cultures and DNA sequence data revealed several unknown species, which are proposed as taxonomic novelties in the Savoryellales and closely related Pleurotheciales. Ascotaiwania latericolla, Helicoascotaiwania lacustris and Pleurotheciella erumpens are described from terrestrial, lentic and lotic habitats from New Zealand and France, respectively. New combinations are proposed for Helicoascotaiwania farinosa and Neoascotaiwania fusiformis. Relationships and systematics of the Savoryellales are discussed in the light of recent phylogenies and morphological patterns newly linked with the order through cultural studies.