The molecular phylogeny of freshwater Dothideomycetes

Abstract

The freshwater Dothideomycetes species are an ecological rather than taxonomic group and comprise approximately 178 meiosporic and mitosporic species. Due to convergent or parallel morphological adaptations to aquatic habitats, it is difficult to determine phylogenetic relationships among freshwater taxa and among freshwater, marine and terrestrial taxa based solely on morphology. We conducted molecular sequence-based phylogenetic analyses using nuclear ribosomal sequences (SSU and/or LSU) for 84 isolates of described and undescribed freshwater Dothideomycetes and 85 additional taxa representative of the major orders and families of Dothideomycetes. Results indicated that this ecological group is not monophyletic and all the freshwater taxa, except three aeroaquatic Tubeufiaceae, occur in Pleosporomycetidae as opposed to Dothideomycetidae. Four clades comprised of only freshwater taxa were recovered. The largest of these is the Jahnulales clade consisting of 13 species, two of which are the anamorphs Brachiosphaera tropicalis and Xylomyces chlamydosporus. The second most speciose clade is the Lindgomycetaceae clade consisting of nine taxa including the anamorph Taeniolella typhoides. The Lindgomycetaceae clade consists of taxa formerly described in Massarina, Lophiostoma, and Massariosphaeria e.g., Massarina ingoldiana, Lophiostoma breviappendiculatum, and Massariosphaeria typhicola and several newly described and undescribed taxa. The aquatic family Amniculicolaceae, including three species of Amniculicola, Semimassariosphaeria typhicola and the anamorph, Anguillospora longissima, was well supported. A fourth clade of freshwater species consisting of Tingoldiago graminicola, Lentithecium aquaticum, L. arundinaceum and undescribed taxon A-369-2b was not well supported with maximum likelihood bootstrap and Bayesian posterior probability. Eight freshwater taxa occurred along with terrestrial species in the Lophiostoma clades 1 and 2. Two taxa lacking statistical support for their placement with any taxa included in this study are considered singletons within Pleosporomycetidae. These singletons, Ocala scalariformis, and Lepidopterella palustris, are morphologically distinct from other taxa in Pleosporomycetidae. This study suggests that freshwater Dothideomycetes are related to terrestrial taxa and have adapted to freshwater habitats numerous times. In some cases (Jahnulales and Lindgomycetaceae), species radiation appears to have occurred. Additional collections and molecular study are required to further clarify the phylogeny of this interesting ecological group.

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

“…For the SSU and LSU datasets, we sampled taxa from the major orders of the Pleosporomycetidae and Dothideomycetidae currently included in the Dothideomycetes ). Taxa included in the present study were obtained from a study on the molecular phylogeny of freshwater Dothideomycetes ), as well as other studies on the phylogenetic relationships among dothideomyceteous fungi (Wu et al 2011, Zhang et al 2012. We also included members of the Patellariales and other apothecial dothideomycete members such as Catinella olivacea (Batsch) Boudier to test whether Minutisphaera-like fungi share phylogenetic affinities with the apothecial dothideomycetous fungi.…”

“…For ascospore septum position, the decimal system (Shoemaker 1984) was used. Single ascospore cultures were obtained according to Shearer et al (2004). For the Japanese collections, ascomata formation was induced by placing a small piece of mycelial culture on rice straw agar (RSA; Tanaka and Harada 2003).…”

“…Most species of freshwater Dothideomycetes belong in the Pleosporales (Zhang et al 2012) or Jahnulales (Pang et al 2002, Campbell et al 2007, Suetrong et al 2011), although few taxa have affinities to the Capnodiales and Tubeufiaceae ).…”

Splanchnonema-like species in Pleosporales: introducing Pseudosplanchnonema gen. nov. in Massarinaceae

“…Pseudosplanchnonema differs from M. eburnea in having smaller ascomata lacking a clypeus, a thicker peridium composed of two layers the inner of hyaline and outer of dark brown cells, anastomosing pseudoparaphyses, and larger, dark brown, 1-septate, guttulate ascospores which sometimes have pseudosepta. Several asexual genera have been shown to be associated with Massarinaceae by molecular phylogenetic studies (Kodsueb et al 2007, Shearer et al 2009, Suestrong et al 2009, Zhang et al 2012. Byssothecium, represented by B. circinans differs from Pseudosplanchnonema in having minute, thin-walled conidiomata and subglobose, broadly papillate pseudothecia with smaller asci and ascospores in its sexual morph (Boise 1983).…”

“…Bose (Zhang et al 2009b(Zhang et al , 2012; molecular data is lacking for many other Massarina species. Massarina eburnea, M. cisti and M. igniaria (C. Booth) Aptroot together with Byssothecium circinans Fuckel forms a distinct monophyletic clade which can be considered as Massarina sensu stricto (Liew et al 2002, Zhang et al 2012, Hyde et al 2013 (Kodsueb et al 2007, Shearer et al 2009, Suetrong et al 2009, Zhang et al 2012, Hyde et al 2013, Quaedvlieg et al 2013.…”