An overview of the Hexagenitidae (Ephemeroptera) from the Crato Formation (Aptian, Lower Cretaceous) of Brazil, with the description of a new species

ABSTRACT

Among mayflies, the Hexagenitidae is the most common family of the Cretaceous, including in the world-renowned Crato Formation (Aptian) of northeastern Brazil. However, most of the Crato mayfly fauna was described based on nymphs, which, due to their ontogenetic development, may present numerous continuous characters. As a consequence, many unclear taxa have been described, and their taxonomic position needs to be re-evaluated. We here present a checklist and revision of some previously described species from the Crato Formation and the description of new specimens. We propose a new species, Protoligoneuria heloisae sp. nov., based on a previously described adult erroneously referred to within Oligoneuriidae. Further adult specimens of Hexagenitidae are here described in detail, presenting new morphological data and variations that were, up to now, unknown for Hexagenitidae of the Crato Formation. Lastly, we briefly discuss the genus Cratohexagenites. Our new findings further add to the taxonomical and morphological diversity of the adult mayfly fauna of the Crato Formation.

KEYWORDS:

• Taxonomy
• aquatic insects
• Araripe Basin
• Neotropics

Supplementary material

Supplemental data for this article can be accessed here.

Acknowledgements

We thank Pavel Sroka and two anonymous reviewers, whose comments improved this manuscript. We thank Janice Peters for comments on the morphology of the specimen MPSC I 1559. APS thanks Renan Bantim (LPU) and Lucio Silva (MPSC) for access to the collections, and David Grimaldi and Courtney Richenbacher (AMNH) for providing pictures of specimen AMNH 43499. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) under grants 312360/2018-5 to TR and 309666/2019-8 to FFS, and Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP under grant BP3-013900202.01.00/18 to AAFS. RJG acknowledges the financial support of the Grant Agency of the Czech Republic (No. 21-05216S) and institutional support RVO 60077344 (IE, BC CAS). The stay of RJG at SMNS was supported by a Georg Forster Research Fellowship for Experienced Researchers by the Alexander von Humboldt Foundation in 2019 and SYNTHESYS (http://www.synthesys.info/), which was financed by the European Community Research Infrastructure Action in 2020.

Disclosure statement

The authors declare no competing interests.

Author contributions

APS, FFS, AAFS and TR conceived the study; APS and TR administrated the project; AAFS carried out the fieldwork and administrated the data collection; APS, RJG, FFS and AHS investigated and validated the data; APS wrote the manuscript; APS, RJG, FFS, AAFS, AHS and TR discussed the results and revised the manuscript.

Additional information

Funding

This work was supported by the Alexander von Humboldt-Stiftung [Georg Forster Research Fellowship for Experienced Researchers]; Conselho Nacional de Desenvolvimento Científico e Tecnológico [309666/2019-8,312360/2018-5]; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior [001]; Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico [BP3-013900202.01.00/18]; Grantová Agentura České Republiky [21-05216S].České Republiky [21-05216S]; SYNTHESYS.