Freshwater Ascomycetes: Minutisphaera (Dothideomycetes) revisited, including one new species from Japan

Abstract

During investigations of freshwater ascomycetes we found one interesting taxon from Aomori (Japan), as well as three additional taxa from North Carolina (USA), which were morphologically similar to Minutisphaera, a recently described freshwater fungus in the Dothideomycetes. The ascomata of all the collections bore dark hair-like structures around the ostiolar region, obovoid to obclavate bitunicate asci, and one to three septate hyaline to brown ascospores with a sheath (in material from Japan), and with both sheath and appendages (in material from the USA). The apothecial ascomata of these taxa, however, differ from those of the type species of the genus, which are perithecial. Two collections of Minutisphaera-like fungi from the USA were morphologically quite similar but differed in ascospore size. To assess the phylogenetic affinities of Minutisphaera-like taxa with the type species, M. fimbriatispora, we sequenced 18S and 28S nrDNA of five newly collected strains of Minutisphaera. We also sequenced the nrDNA for the entire internal transcribed spacer region of 10 strains to assess interspecific and intraspecific variation with M. fimbriatispora. Additionally we examined the secondary metabolite profiles of two strains from USA. Based on maximum likelihood and Bayesian analyses of combined 18S and 28S, and separate ITS sequences, as well as examination of morphology, we describe and illustrate a new species, M. japonica. One collection from North Carolina is confirmed as M. fimbriatispora, while two other collections are Minutisphaera-like fungi that had a number of similar diagnostic morphological characters but differed only slightly in ascospore sizes. The phylogeny inferred from the internal transcribed spacer region suggested that two out of the three North Carolina collections may be novel and perhaps cryptic species within Minutisphaera. Organic extracts of Minutisphaera from USA, M. fimbriatispora (G155-1) and Minutisphaera-like taxon (G156-1), revealed the presence of palmitic acid and (E)-hexadec-9-en-1-ol as major chemical constituents. We discuss the placement of the Minutisphaera clade within the Dothideomycetes. The description of the genus Minutisphaera is emended to accommodate M. japonica within Minutisphaera. Abstract: During investigations of freshwater ascomycetes we found one interesting taxon from Aomori (Japan), as well as three additional taxa from North Carolina (USA), which were morphologically similar to Minutisphaera, a recently described freshwater fungus in the Dothideomycetes. The ascomata of all the collections bore dark hair-like structures around the ostiolar region, obovoid to obclavate bitunicate asci, and one to three septate hyaline to brown ascospores with a sheath (in material from Japan), and with both sheath and appendages (in material from the USA). The apothecial ascomata of these taxa, however, differ from those of the type species of the genus, which are perithecial. Two collections of Minutisphaera-like fungi from the USA were morphologically quite similar but d...

Acetophenone derivatives from a freshwater fungal isolate of recently described Lindgomyces madisonensis (G416)

“…As of 2011, approximately 127 chemical structures had been reported from about 30-40 freshwater fungal species (El-Elimat et al, 2014a, El-Elimat et al, 2014b, Hernández-Carlos and Gamboa-Angulo, 2011. To ameliorate this knowledge gap, studies were initiated on the chemical mycology of freshwater ascomycetes in North Carolina, USA (El-Elimat et al, 2014a, El-Elimat et al, 2014b, Raja et al, 2013a, Raja et al, 2013b, representing the first systematic study of freshwater ascomycetes from this region of North America. Ongoing investigations led to the isolation of five new acetophenones (1, 3, 4, 6, and 7), along with 4′-methoxymadisone (2) and dihydroallovisnaginone (5), from a fungal isolate recently described as Lindgomyces madisonensis (G416) Raja & Oberlies (Crous et al, 2015).…”

Greensporones: Resorcylic Acid Lactones from an Aquatic Halenospora sp.

“…41,42 DNA extraction, PCR amplification, and sequencing were performed according to previously published procedures. 10,11,43−45 A BLAST search in GenBank using the complete ITS rDNA sequence showed 98% sequence similarity of the strain G87 with several members of the Leotiomycetes, Ascomycota. In particular, strain G87 displayed homology with a number of sequences belonging to Halenospora varia (Anastasiou) (E.B.G.…”

2. Phylogeny of the Dothideomycetes and other classes of freshwater fissitunicate Ascomycota

“…2.1L). Based on morphology, this taxon is similar to species in Minutisphaera (Raja et al 2013b); however, molecular data are necessary to clarify its phylogenetic placement.…”