Analysis of the type of Synedra acus var. ostenfeldii (Bacillariophyta) and its transfer to the genus Fragilaria

ABSTRACT

The type material of Synedra acus var. ostenfeldii Willi Krieg. was investigated using light and scanning electron microscopy. The species is one of the few fragilarioid taxa that forms stellate colonies. Its morphology was compared with that of Fragilaria tenera var. lemanensis Druart, Lavigne & M.Robert, another taxon forming star-shaped colonies, on the type slide and in material from a neighbouring lake. The results show both taxa not being conspecific based on valve outline, valve dimensions and presence of spines. Based on the observations, Synedra acus var. ostenfeldii is transferred to the genus Fragilaria as F. ostenfeldii (Willi Krieg.) Van de Vijver, Alexson & Reavie comb. nov. stat. nov. whereas F. tenera var. lemanensis is raised to species level as Fragilaria lemanensis (Druart, Lavigne & M.Robert) Van de Vijver, Ector & Straub stat. nov. Brief notes on their ecology are added.

KEYWORDS:

• Diatom plankton
• morphology
• Fragilaria
• taxonomy
• type material

Acknowledgments

Dr Regine Jahn and Dr Nelida Abarca (Botanical Garden Berlin-Dahlem) are thanked for locating and sending us the Krieger samples. Dr Frédéric Rimet and Mr Jean-Claude Druart (TCC, Thonon-les-Bains, France) are acknowledged for having retrieved and sent the type slides of F. tenera var. lemanensis. The editor, Prof. Benoît Schoefs, and two anonymous reviewers are thanked for their constructive comments that greatly improved this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

Bart Van de Vijver: LM and SEM analysis of all materials, discussion of results, development, writing, revision and editing of the manuscript.

Elizabeth E. Alexson: discussion of results, development, writing, revision and editing of the manuscript.

Euan D. Reavie: discussion of results, development, writing, revision and editing of the manuscript.

François Straub: provision of samples and data on Neuchâtel Lake, discussion of results, revision of the manuscript.

Gunnar Steinn Jónsson: provision of samples from Lake Thingvallavatn, discussion of the results, revision and editing of the final manuscript.

Luc Ector: provision of literature, discussion of results, revision and editing of the manuscript.