Fragilaria subrecapitellata (Fragilariaceae, Bacillariophyta), a new diatom species from Switzerland

Abstract

During a biomonitoring assignment in the Swiss canton Ticino, an unknown Fragilaria taxon was discovered that could not be identified using the currently available literature. The results of a morphological comparison with the type material of F. recapitellata, based on light and scanning electron microscopy, showed that the new Swiss taxon has sufficient differences to be separated as a new species: Fragilaria subrecapitellata sp. nov. The new species can be separated by its lanceolate to elliptic-lanceolate valve outline with convex valve margins, and its smaller valves compared to F. recapitellata. The distribution and iconography of F. recapitellata in literature data is analysed. As a result of this analysis, Fragilaria deformis is appointed as the correct name for the taxon generally known as F. candidagilae or F. capucina var. capitellata (Grunow) Lange-Bertalot in Krammer & Lange-Bertalot.

Keywords:

• Europe
• Fragilaria
• morphology
• new species
• type material

Acknowledgments

The authors wish to thank François Straub (La Chaux-de-Fonds, Switzerland) as well as Christa Gufler and Margrit Ensner Egloff (AquaPlus, Zug, Switzerland) for their valuable help and support in sampling, determining and counting the diatoms. The Ufficio della protezione delle acque e dell'approvvigionamento idrico (UPAAI) granted us the permission to use the diatom material and chemical data of the year 2018. Dr Tanja M. Schuster, curator of the Grunow collection at W is thanked for sending us the material for Grunow sample 118. Funding for this research was partly provided in the framework of the project DIATOMS (LIST – Luxembourg Institute of Science and Technology). Two anonymous reviewers are thanked for their valuable comments that greatly improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.