Mediocremonas mediterraneus, a New Member within the Developea

Abstract

The stramenopiles are a large and diverse group of eukaryotes that possess various lifestyles required to thrive in a broad array of environments. The stramenopiles branch with the alveolates, rhizarians, and telonemids, forming the supergroup TSAR. Here, we present a new genus and species of aquatic nanoflagellated stramenopile: Mediocremonas mediterraneus, a free-swimming heterotrophic predator. M. mediterraneus cell bodies measure between 2.0-4.0 lm in length and 1.2-3.7 lm in width, possessing two flagella and an oval body morphology. The growth and grazing rate of M. mediterraneus in batch cultures ranges from 0.68 to 1.83 d À1 and 1.99 to 5.38 bacteria/h, respectively. M. mediterraneus was found to be 93.9% phylogenetically similar with Developayella elegans and 94.7% with Develorapax marinus, two members within the class Developea. The phylogenetic position of the Developea and the ability of M. mediterraneus to remain in culture make it a good candidate for further genomic studies that could help us to better understand phagotrophy in marine systems as well as the transition from heterotrophy to phototrophy within the stramenopiles.

Monophyly of diverse Bigyromonadea and their impact on phylogenomic relationships within stramenopiles

“…Previously, only SSU rRNA phylogenies could be used to test the monophyly of the Bigyromonadea, and such analyses consistently failed to support the monophyly, typically showing Developea with oomycetes and Pirsoniales with ochrophytes (Aleoshin et al, 2016;Kühn et al, 2004;Weiler et al, 2020). In contrast, phylogenomic data consistently and strongly supports the monophyly of these two groups, and shows each to include multiple distinct genera.…”

“…One such clade is the subphylum Bigyromonadea, which was proposed to include the class Developea (Aleoshin et al, 2016) and order Pirsoniales (Cavalier-Smith, 1998). The monophyly of the Bigyromonadea is essentially untested, since only small subunit rRNA (SSU) data are known from all but a single species (the exception being Developayella elegans, for which a transcriptome is available), and the two groups never branch together in SSU phylogenies (Aleoshin et al, 2016;Cavalier-Smith and Chao, 2006;Kühn et al, 2004;Weiler et al, 2020).…”

“…The copyright holder for this preprint this version posted November 19, 2021. ; https://doi.org/10.1101/2021.11.17.469027 doi: bioRxiv preprint Developea are marine bacterivores, including Developayella elegans (Leipe et al, 1996;Tong, 1995) and Mediocremonas mediterraneus (Weiler et al, 2020), and the marine eukaryovore Develorapax marinus (Aleoshin et al, 2016). Pirsoniales are parasites of other microbes, including Pirsonia guinardiae (Schnepf et al, 1990) and P. punctigera (Schweikert and Schnepf, 1997).…”

Monophyly of Diverse Bigyromonadea and their Impact on Phylogenomic Relationships Within Stramenopiles

“…Developayella sp." in GenBank, it was recently re-assigned as Mediocremonas mediterraneus (Weiler et al, 2020)). Interestingly, the SSU rRNA sequences of the four "Developayella" fell into two separate groups, indicating two different species (and genera) were assigned as Developayella elegans; sub-clade I consisted of Developayella elegans U37107, Developayella sp.…”

“…Developea are marine bacterivores, including Developayella elegans (Leipe et al, 1996;Tong, 1995) and Mediocremonas mediterraneus (Weiler et al, 2020), and the marine eukaryovore Develorapax marinus (Aleoshin et al, 2016). Pirsoniales are parasites of other microbes, including Pirsonia guinardiae (Schnepf et al, 1990) and P. punctigera (Schweikert and Schnepf, 1997).…”