The diatom genus Humidophila (Bacillariophyta) in an historic Delogne sample with the description of 2 new species

ABSTRACT

During the analysis of a voucher sample from Frahan (Belgium) collected by the Belgian diatomist Charles-Henri Delogne, seven species from the genus Humidophila (Bacillariophyta) have been observed. Two species could not be identified using the currently available literature and are described as new to science. Humidophila delognei sp. nov. has always been identified in the past as H. contenta, but based on recent analysis of the original type material of the latter, it was clear that the currently accepted concept of the species was wrong. The new species is characterised by parallel valve margins, a linear valve outline, a distinct central fascia and T- or Y-shaped raphe endings. The other new species, H. aspera sp. nov., has undulating valve margins and distinct, though irregular siliceous markings in the central and axial area. The sample from Frahan was also indicated in 1885 by Henri Van Heurck as being the original material for the newly described species Humidophila (Navicula) flotowii, long considered a synonym of H. perpusilla. Both species can, however, be separated based on a different length/width ratio, with H. flotowii showing more slender, elongated valves. Other Humidophila species in the sample include H. contenta, H. laevissima, H. perpusilla and H. simplex. Navicula fragilarioides, a new name once introduced for Fragilaria laevissima, the basionym of H. laevissima, is lectotypified based on an original Krasske slide.

KEYWORDS:

• Charles-Henri Delogne
• Frahan
• collection sample
• Humidophila
• lectotypification
• new species

Acknowledgments

The authors wish to thank Mrs C. Horions, Ms K. Wilfert and Ms E. Wilfert for their help with the cataloguing of the Delogne collection, part of the Van Heurck collection in Meise Botanic Garden (Belgium). Dr P. Mansfeld (Krasske collection, Kassel, Germany) is thanked for his help in retrieving the original type slide of N. fragilarioides. Wolf-Henning Kusber is thanked for his taxonomic advice and his help with the PhycoBank registration.

The authors also want to thank three anonymous reviewers and the editor for their valuable comments that help to improve this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Charlotte Goeyers

Contribution: provision of literature, generation of SEM analysis, discussion of results, revision and editing of the manuscript.

Bart Van de Vijver

Contribution: generation and analyses of LM and SEM materials, discussion of results, development, writing, revision and editing of the manuscript.

Additional information

Funding

This research was supported by the Fund for Scientific Research—Flanders (FWO): funding of research fellow Charlotte Goeyers (aspirant grant 11E1221N) was provided by Meise Botanic Garden in collaboration with FWO.