A new genus and family for the misclassified chytrid,Rhizophlyctis harderi

Abstract

A chytrid first discovered in Mediterranean sands and called Rhizophlyctis harderi was classified in the genus Rhizophlyctis based on its interbiotic vegetative thalli with multiple rhizoidal axes and resting thalli with tufts of rhizoid-like appendages. Developmental, electron microscopic and molecular analyses, however, have brought into question the proper placement of this chytrid. Because its original description was in German and not Latin, the name R. harderi is not validly published. We found that this chytrid produces three thallus forms that could place it in three different morpho-genera: Rhizophydium, Phlyctochytrium or Rhizophlyctis. The ultrastructural architecture of its zoospore is different from that of zoospores of Rhizophlyctis rosea, the type species for Rhizophlyctis, and shares zoospore ultrastructural characteristics with the Rhizophydiales. Zoospores of this chytrid exhibit a distinctive kinetosome-associated structure (KAS), a curved shield bridged to two of the kinetosomal triplets and a layered cap anterior to the kinetosome. Phylogenetic analyses of nuc rDNA also support the placement of this chytrid in the Rhizophydiales and not in the Rhizophlyctidales. Given its molecularly based phylogenetic placement and its distinctive zoospore architecture, we describe this chytrid in a new genus, Uebelmesseromyces, in the Rhizophydiales and erect Uebelmesseromycetaceae as a new family to accommodate it.

Chytrids dominate arctic marine fungal communities

“…Each closely related order contains known parasites of algae, capable of infecting diatoms (Simmons et al ., ), producing endogenous resting spores (Karpov et al ., ) and existing in marine ecosystems (Lepelletier et al ., ). Halotolerance and extreme conditions are suggested to be a driving force in the evolution of marine chytrids (Powell et al ., ).To this end, our data suggest the sea ice ecosystem could be a large reservoir and driver of cryptic fungal diversity and provides further evidence that chytrids are integral members throughout the world's cryosphere (Freeman et al ., ; Naff et al ., ).…”

Comparison of sterol and fatty acid profiles of chytrids and their hosts reveals trophic upgrading of nutritionally inadequate phytoplankton by fungal parasites

“…). As expected, zoospores of both chytrid species were rich in lipids, presenting a large lipid globule, a characteristic morphological feature of chytrids (Powell et al ., ; Van den Wyngaert et al ., ). Chytrids’ high lipid contents could explain the observed increase in total FA contents in Host+Sporangia fraction compared with the uninfected diatom host.…”

Integrating chytrid fungal parasites into plankton ecology: research gaps and needs

“…Second, and to the goal of achieving higher resolution, the large ribosomal unit (LSU) has proven a promising genetic marker for chytrids delineation, as it exhibits more variability than the SSU. Thus, it has been used to delineate new orders such as Rhizophydiales, Rhizophlyctidales, Cladochytriales, Lobulomycetales and Polychytriales, and to confirm existing orders (Spizellomycetales, Chytridiales), and for delineation at family, genus and species level (Davis et al, 2015;Letcher et al, 2015b;Powell et al, 2015;Leshem et al, 2016). Third, of the rRNA markers, the intergenic transcribed spacer (ITS) has been proposed as the most suitable molecular marker for fungal barcoding (Schoch et al, 2012).…”