Two new species of the diatom genus Navicula Bory (Bacillariophyceae) from Vietnam (Southeast Asia)

Abstract

We present light and scanning electron microscopical observations on two new species of Navicula Bory sensu stricto from Vietnam. These new species, Navicula babeiensis Chudaev, Glushchenko, Kulikovskiy & Kociolek sp. nov. and Navicula pseudokuseliana Chudaev, Glushchenko, Kulikovskiy & Kociolek sp. nov. are described and distinguished from others in the genus on the basis of valve outline and shape of the apices, as well as stria and areola densities. These species possess all the typical morphological features for the genus, including uniseriate lineolate striae covered by internal convex hymenes, median raphe with accessory rib, and external distal raphe ends that are hooked in the characteristic way for the genus. Comparisons with similar taxa are given. Our new data extend the information about the diversity of diatoms in general and for Navicula taxa specifically, in Southeast Asia.

Keywords:

• diatoms
• new species
• Navicula
• morphology
• Vietnam
• Southeast Asia

Acknowledgements

SEM studies were carried out at the Shared Research Facility ‘Electron microscopy in life sciences' at Moscow State University (Unique Equipment ‘Three-dimensional electron microscopy and spectroscopy'). This publication is based on research carried out with financial support by Russian Science Foundation (19–14–00320) for LM sample investigation and by framework of the state assignment (theme AAAA-A19-119041190086-6) for finishing manuscript. Samples were collected during expeditions organized and permitted by the Joint Russian-Vietnam Tropical Centre, Ecolan 3.2 theme. The work of D.A. Chudaev was carried out within the framework of state programme of the Moscow State University, part 2, item 01 10 (theme 26-2-21).

Disclosure statement

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

Additional information

Funding

This publication is based on research carried out with financial support by Russian Science Foundation [grant number 19–14–00320] for LM sample investigation and by framework of the state assignment (theme AAAA-A19-119041190086-6) for finishing manuscript and SEM investigation (theme 26-2-21).