The diatom flora of the Tonle Sap Lake in Cambodia: Centrobacillariophycidae – inventory and description of five new taxa including Praecyclostephanos gen. nov.

Abstract

We provide an update to our knowledge of the centric diatoms in the Tonle Sap Lake (Cambodia) by providing a new and highly detailed iconography of all observed taxa based on light and scanning electron microscopy. We highlight a distinctive flora, including a new genus Praecyclostephanos gen. nov. and five taxa new to science: Aulacoseira micropunctata sp. nov., A. spiralorimoportula sp. nov., Praecyclostephanos boengchhmariensis sp. nov., Stephanodiscus tonlesapensis sp. nov. and Urosolenia anlongreangensis sp. nov. The flora is mainly dominated by several species of the genus Aulacoseira. Within the Aulacoseira populations forming the background of the diatom community, taxa that reveal the change in environmental conditions appear sporadically, often as blooms. The wide range of life-forms related to their ability to float is another remarkable aspect of the centric diatom flora. This variability appears at several taxonomic scales. At the genus level, colonial and solitary life-forms are very well represented in their diversity. At the sub-genus level, mainly among the Aulacoseira species, communities present a wide range of buoyancy metrics. Accordingly, in addition to the taxonomic review, we provide additional information related to their potential as bioindicators to monitor the hydrodynamic aspects of the lake in both space and time.

Keywords:

• buoyancy
• life-form
• lower Mekong basin
• Stephanodiscus
• taxonomy
• Urosolenia

Acknowledgements

We thank all Inland Fisheries Research and Development Institute (IFReDI) staff members, scientists and technicians, for the logistic preparation and their assistance during field work. We particularly appreciate the comments of Mr. Rolf Klee. Special thanks also to Thomas K. Pool (University of Washington, Seattle, USA) and Mathieu Chevalier (IFREMER, Centre de Bretagne, DYNECO, Laboratoire d’Ecologie Benthique Côtière, France) involved in the project TLSCC.

Disclosure statement

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

Additional information

Funding

The Agence Nationale de la Recherche (Belmont Forum TLSCC, N ° ANR-13-JCLI-0003-01) provided funding.