Unexpected ubiquity of heart‐shaped scale morphotype in Centroplasthelida (Haptista): Ancestral trait or multiple acquisitions?

Abstract Centrohelids (Haptista: Centroplasthelida) are axopodial protists with a remarkable diversity of external siliceous scale morphologies. It is believed that the last common ancestor of centrohelids had a double layer of siliceous scales composed of plate scales closer to a cell surface and s...

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Bibliographic Details
Published in:Journal of Eukaryotic Microbiology
Main Authors: Gerasimova, Elena A., Mindolina, Yulia V., Tikhonenkov, Denis V., Kataev, Vladimir Y., Balkin, Alexander S., Mikhailov, Kirill V., Zagumyonnyi, Dmitry G., Plotnikov, Andrey O., Zlatogursky, Vasily V.
Other Authors: Russian Science Foundation
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2023
Subjects:
Microbiology
Antarc*
Antarctica
Online Access:http://dx.doi.org/10.1111/jeu.12992
https://onlinelibrary.wiley.com/doi/pdf/10.1111/jeu.12992
Description
Summary:Abstract Centrohelids (Haptista: Centroplasthelida) are axopodial protists with a remarkable diversity of external siliceous scale morphologies. It is believed that the last common ancestor of centrohelids had a double layer of siliceous scales composed of plate scales closer to a cell surface and spine scales radiating outwards. The characteristic morphotype of spine scales with a heart‐shaped base was once believed to be a unique feature of the genus Choanocystis , as it was defined by Siemensma and Roijackers (1988). Further research revealed that this morphology is present in different and sometimes distantly related lineages: Ozanamiidae, Meringosphaeridae, and Marophryidae. Here, we report the fourth clade, Pterocystidae, which is also revealed to contain representatives having this phenotype. Cernunnos gen. nov. is erected here to place Cernunnos uralica sp. nov., Cernunnos arctica sp. nov., Cernunnos america sp. nov., and Cernunnos antarctica Tikhonenkov et Mylnikov, 2010, Gerasimova comb. nov. C . uralica was studied with scanning electron microscopy and SSU rDNA sequencing. Molecular phylogenetic analysis placed it into marine environmental clade P within Pterocystida. The ubiquity of spine scales with heart‐shaped bases could be an example of parallel evolution, but taking into account the considerable similarity it is likely an ancestral trait, acquired from the last common ancestor of centrohelids.

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