Psammothidium elnatanianum sp. nov. (Achnanthidiaceae, Bacillariophyta) a new diatom species found in Holocene sediments (Meghalayan Age) of the Xingu River, Eastern Amazon

ABSTRACT

An unknown species of Psammothidium (Achnanthidiaceae) was found in core sediment (~4000 cal yr BP) collected from Xingu ria, located in eastern Amazon Basin (Brazilian Amazon). The detailed morphology of the new species was examined and described using light (LM) and scanning electron (SEM) microscopy. The new species described here is mainly characterized by small valve dimensions, an irregular and expanded central area in rapheless valve (RLV) clearly visible in LM. Under SEM observations, the new species show slightly radiate striae with rectangular to rounded areolae present both on the surface and the valve mantle. Morphology and ecology of the new species is compared to those already described for the genus. Moreover, information about core chronology and the co-occurrence of other diatom species in the sample are also provided.

KEYWORDS:

• Biodiversity
• diatoms
• monoraphid
• Amazonian rias
• paleolimnology

Acknowledgments

We owe thanks to Dr. Andre Oliveira Sawakuchi, coordinator of the main project, as well as all to the professionals involved in the collection and analysis of the sediment core. We are also grateful to the two anonymous reviewers for their valuable comments and suggestions to improve the manuscript. CEM thanks CNPq [Conselho Nacional de Desenvolvimento Científico e Tecnológico] for Research Fellowship [n° CNPQ 305031/2016-3].

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

Krysna S. Morais: preparation of the images, bibliographic research, writing and editing of the manuscript.

Lívia F. Costa: discussion of results, bibliographic research, revision of the manuscript.

Carlos E. de M. Bicudo: discussion of the results and revision of the manuscript.

Carlos E. Wetzel: scanning electron microscopy, bibliographic research, discussion of the results and revision of the manuscript.

Additional information

Funding

This study was carried out within the scope of the project ”The response of the sedimentary dynamics of the Xingu and Tapajós rivers to climate change and hydropower: risks for the conservation of biodiversity and production of energy in the Amazon” with support from FAPESP [Fundação de Amparo Pesquisa à do Estado de São Paulo [grant no. 2016/02656-9]”. The results of the article were funded by CAPES, cited in: ”KSM thanks you for your doctoral scholarship [CAPES, Coordination for the Improvement of Higher Education Personnel].