What Drives the Diversity of the Most Abundant Terrestrial Cercozoan Family (Rhogostomidae, Cercozoa, Rhizaria)?

Abstract

Environmental sequencing surveys of soils and freshwaters revealed high abundance and diversity of the Rhogostomidae, a group of omnivorous thecate amoebae. This is puzzling since only a few Rhogostomidae species have yet been described and only a handful of reports mention them in field surveys. We investigated the putative cryptic diversity of the Rhogostomidae by a critical re-evaluation of published environmental sequencing data and in-depth ecological and morphological trait analyses. The Rhogostomidae exhibit an amazing diversity of genetically distinct clades that occur in a variety of different environments. We further broadly sampled for Rhogostomidae species; based on these isolates, we describe eleven new species and highlight important morphological traits for species delimitation. The most important environmental drivers that shape the Rhogostomidae community were soil moisture, soil pH, and total plant biomass. The length/width ratio of the theca was a morphological trait related to the colonized habitats, but not the shape and size of the aperture that is often linked to moisture adaption in testate and thecate amoebae.

From Forest Soil to the Canopy: Increased Habitat Diversity Does Not Increase Species Richness of Cercozoa and Oomycota in Tree Canopies

“…Also, cercozoan communities were surprisingly similar between canopy leaves and leaf litter on the ground (Figure 3A), suggesting that the phyllosphere may substantially contribute to community assembly of cercozoan litter communities. A growing number of studies lend support to this hypothesis by identifying particular cercozoan species predominantly adapted to life in the phyllosphere (Dumack et al, 2017;Flues et al, 2017;Öztoprak et al, 2020). Oomycetes on the other hand showed significantly different patterns of beta diversity between phyllosphere and ground litter, showing that this pattern cannot be confirmed for protists in general and that different protistan groups do not behave uniformly.…”

To the canopy and beyond: Air samples reveal wind dispersal as a driver of ubiquitous protistan pathogen assembly in tree canopies

“…OTUs assigned to the Rhogostomalineage within the Cryomonadida dominated the samples. Rhogostoma species form resting stages resistant against desiccation for up to three months, although they form no cysts or zoospores (Mylnikova & Mylnikov, 2012;Öztoprak et al, 2020). Assulina seminulum, has a silica test with a remarkable size of 60-90 µm (Lara et al, 2010), and dominated the air dispersed Euglyphids, demonstrating that protists of this size can be still easily dispersed by air (Finlay, 2002).…”

Novel Endosymbionts in Rhizarian Amoebae Imply Universal Infection of Unrelated Free-Living Amoebae by Legionellales

“…surface soil ( Khanipour Roshan et al., 2021 ). Rhogostoma represents a genus of thecofilosean amoebae that is especially abundant in soils ( Degrune et al., 2019 ; Fiore-Donno et al., 2019 ; Öztoprak et al., 2020 ), wastewater treatment plants ( Matsunaga et al., 2014 ; Remmas et al., 2016a ; Remmas et al, 2016b ; Öztoprak et al., 2020 ), and water filters ( Domingo Fernandez, 2019 ), and their potential as a reservoir for Legionellales requires further investigation.…”

“…We aimed to investigate whether Rhizaria may function as hosts for Legionellales; as a starting point, we chose to screen the amoeboid Thecofilosea (Cercozoa, Rhizaria) since molecular investigations indicate an occasional dominance of these small and inconspicuous microorganisms in soils, wastewater treatment plants, and water filters ( Matsunaga et al., 2014 ; Remmas et al., 2016a ; Remmas et al, 2016b ; Seppey et al., 2017 ; Fernandez, 2019 ; Öztoprak et al., 2020 ).…”