Identification of an epiphytic diatom on Nitzschia sigmoidea (Bacillariophyceae)

ABSTRACT

Epiphytism on benthic motile diatoms is not common and can be considered a phoretic habitat. Nitzschia sigmoidea is a very long diatom which often exhibits epiphytes on its frustule. It was found abundantly in a small regulated stream in Provence and about half of the individuals had a variable number of adnate epiphytes on them. Examination of fresh material under a scanning electron microscope revealed that the epiphytes were diatoms belonging to the species Fallacia helensis. This species had not been reported as epiphytes on other diatoms before. More research is needed to understand the relationship between the two species and, more generally, to investigate phoretic epiphytism as an original biotic interaction between diatoms.

Graphical Abstract

KEYWORDS:

• Biotic interactions
• diatoms
• epiphytism
• parasitism
• phoresy

Acknowledgments

The members of the Association des Diatomistes de Langue Française (ADLaF) are thanked for helpful comments during the conference of the association held in Meise (September 2018). The authors are grateful to the reviewers for their useful comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Notes on contributors

Vincent Roubeix

Vincent Roubeix is a research engineer in freshwater ecology at Irstea, Aix-en-Provence, France.Contribution: he collected the biofilm samples, analysed them under an optical microscope and made the micrographs and the movie. He wrote the manuscript.

Françoise Chalié

Françoise Chalié is a research scientist in paleo-limnology, paleo-climatology and paleo-environments at CEREGE, Aix-en-Provence, France.Contribution: she helped with sample preparation and SEM observations, provided helpful references and performed a critical reading of the manuscript.