Consolidation of Chloridium: new classification into eight sections with 37 species and reinstatement of the genera Gongromeriza and Psilobotrys

New genera and species with chloridium-like morphotype in the Chaetosphaeriales and Vermiculariopsiellales

In this study, we investigated the morphological and genetic variability of selected species belonging to the genus Chloridium sensu lato, some also referred to as chloridium-like asexual morphs and other undescribed morphologically similar fungi. These species do not conform to the revised generic concept and thus necessitate a re-evaluation in terms of taxonomy and phylogeny. The family Chaetosphaeriaceae (Chaetosphaeriales) encompasses a wide range of asexual morphotypes, and among them, the simplest form is represented by Chloridium sect. Chloridium. The morphological simplicity of the Chloridium morphotype has historically led to the amalgamation of numerous unrelated species, thereby creating a heterogeneous genus. By conducting phylogenetic reconstruction of four DNA loci and examining a set of 71 strains, including all available ex-type and other non-type strains as well as holotypes and other herbarium material, we were able to gain new insights into the relationships between these taxa. Phylogenetic analyses revealed that the studied species are distantly related to Chloridium sensu stricto and can be grouped into two orders in the Sordariomycetes. Within the Chaetosphaeriales, they formed nine well-separated genera in four clades, such as Cacumisporium, Caliciastrum gen. nov., Caligospora gen. nov., Capillisphaeria gen. nov., Curvichaeta, Fusichloridium, Geniculoseta gen. nov., Papillospora gen. nov., and Spicatispora gen. nov. We also established Chloridiopsiella gen. nov. and Chloridiopsis gen. nov. in Vermiculariopsiellales. Four new species and eight new combinations are proposed in these genera. Our study provides a clearer understanding of the genus Chloridium, its relationship to other morphologically similar fungi, and a new taxonomic treatment and molecular phylogeny to facilitate their accurate identification and classification in future research. Taxonomic novelties: New genera: Caliciastrum Réblová, Caligospora Réblová, Capillisphaeria Réblová, Chloridiopsiella Réblová, Chloridiopsis Réblová, Geniculoseta Réblová, Papillospora Réblová, Spicatispora Réblová; New species: Caliciastrum bicolor Réblová, Caligospora pannosa Réblová, Chloridiopsis syzygii Réblová, Gongromerizella silvana Réblová; New combinations: Caligospora dilabens (Réblová & W. Gams) Réblová, Capillisphaeria crustacea (Sacc.) Réblová, Chloridiopsiella preussii (W. Gams & Hol.-Jech.) Réblová, Chloridiopsis constrictospora (Crous et al.) Réblová, Geniculoseta preussii (W. Gams & Hol.-Jech.) Réblová, Papillospora hebetiseta (Réblová & W. Gams) Réblová, Spicatispora carpatica (Hol.-Jech. & Révay) Réblová, Spicatispora fennica (P. Karst.) Réblová; Epitypifications (basionyms): Chaetosphaeria dilabens Réblová & W. Gams, Chloridium cylindrosporum W. Gams & Hol.-Jech. Citation: Réblová M, Nekvindová J (2023). New genera and species with chloridium-like morphotype in the Chaetosphaeriales and Vermiculariopsiellales. Studies in Mycology 106: 199-258. doi: 10.3114/sim.2023.106.04.

Amesia hispanica sp. nov., Producer of the Antifungal Class of Antibiotics Dactylfungins

During a study of the diversity of soilborne fungi from Spain, a strain belonging to the family Chaetomiaceae (Sordariales) was isolated. The multigene phylogenetic inference using five DNA loci showed that this strain represents an undescribed species of the genus Amesia, herein introduced as A. hispanica sp. nov. Investigation of its secondary metabolome led to the isolation of two new derivatives (2 and 3) of the known antifungal antibiotic dactylfungin A (1), together with the known compound cochliodinol (4). The planar structures of 1-4 were determined by ultrahigh performance liquid chromatography coupled with diode array detection and ion mobility tandem mass spectrometry (UHPLC-DAD-IM-MS/MS) and extensive 1D and 2D nuclear magnetic resonance (NMR) spectroscopy after isolation by HPLC. All isolated secondary metabolites were tested for their antimicrobial and cytotoxic activities. Dactylfungin A (1) showed selective and strong antifungal activity against some of the tested human pathogens (Aspergillus fumigatus and Cryptococcus neoformans). The additional hydroxyl group in 2 resulted in the loss of activity against C. neoformans but still retained the inhibition of As. fumigatus in a lower concentration than that of the respective control, without showing any cytotoxic effects. In contrast, 25″-dehydroxy-dactylfungin A (3) exhibited improved activity against yeasts (Schizosaccharomyces pombe and Rhodotorula glutinis) than 1 and 2, but resulted in the appearance of slight cytotoxicity. The present study exemplifies how even in a well-studied taxonomic group such as the Chaetomiaceae, the investigation of novel taxa still brings chemistry novelty, as demonstrated in this first report of this antibiotic class for chaetomiaceous and sordarialean taxa.