A putatively extinct higher taxon of Spirotrichea (Ciliophora) from the Lower Cretaceous of Brazil

Thiago Da Silva Paiva,Ismar De Souza Carvalho

doi:10.1038/s41598-021-97709-2

Thiago Da Silva Paiva, Ismar De Souza Carvalho

Open Access

https://doi.org/10.1038/s41598-021-97709-2

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Journal: Scientific Reports	Publication Date: Sep 27, 2021
Citations: 1	License type: open-access

Affiliation: Universidade Federal do Rio de Janeiro

Abstract

Fossil microeukaryotes are key elements for understanding ancient ecosystems at microscopic level and improving the knowledge on the diversification of microbial life as a whole. We describe Palaeohypothrix bahiensis gen. et sp. nov., an exceptionally well-preserved Lower Cretaceous (Berriasian–Barremian; 145–125 Mya) amber-entrapped microeukaryote, identified as a spirotrich ciliate. The preservation of structures interpreted as the nuclear apparatus and remains of the ciliature revealed a novel ground plan, not found in modern Spirotrichea, thus representing a putatively extinct higher taxon lineage, viz. the Palaeohypotricha nov. tax. Based on cladistic analysis, the new taxon is hypothesized as phylogenetically related to the Protohypotrichia.

Highlights

Fossil microeukaryotes are key elements for understanding ancient ecosystems at microscopic level and improving the knowledge on the diversification of microbial life as a whole
We describe Palaeohypothrix bahiensis gen. et sp. nov., an exceptionally well-preserved Lower Cretaceous (Berriasian–Barremian; 145–125 Mya) amber-entrapped microeukaryote, identified as a spirotrich ciliate
The preservation of structures interpreted as the nuclear apparatus and remains of the ciliature revealed a novel ground plan, not found in modern Spirotrichea, representing a putatively extinct higher taxon lineage, viz. the Palaeohypotricha nov. tax

Summary

Introduction

Fossil microeukaryotes are key elements for understanding ancient ecosystems at microscopic level and improving the knowledge on the diversification of microbial life as a whole. The studied specimen differs from all known modern Spirotrichea for exhibiting the following combination of features: Body 45 × 30 μm, broadly elliptical, dorsoventrally flat about 2:1; contractile vacuole at posterior right quadrant of body; macronuclear DNA replication bands present; adoral zone of membranelles (AZM) distinctly separated in crown and lapel; paroral membrane (hereafter “paroral”) unusually complex, formed by multiple oblique segments adjacent to a long, thick file of cilia bordering a narrow peristome which occupies ca.

Results

Conclusion