Epitypification and emended description of Cyclotella hubeiana, a centric diatom from Central China, with remarks on its distribution and ecology

Abstract

Since its description by Chen and Zhu in 1985 from samples collected in a river and reservoir from Hubei Province (Central China), Cyclotella hubeiana has been reported from several sites in central and southern China. Only line drawings were provided with the original description and the same drawings were used in the subsequent diatom floras from China. The more recent reports of this species come from limnological studies which generally do not provide illustrations. There is therefore a need to better illustrate this taxon. As the type material could not be retrieved, new material was collected from the type locality (Xionghe Reservoir) to elucidate its ultrastructure using light and electron microscopy. The figures published by Chen and Zhu in 1985 are designed as lectotype and the new material as epitype to the lectotype. Characteristics of the valve such as the position of the rimoportula (on a costa, within the ring of marginal fultoportulae) and the absence of central fultoportulae on the valve face suggest that this species is best placed within the genus Cyclotella as presently defined. Its morphology is compared with similar species of Cyclotella and Pantocsekiella. In addition, in a study on Qiandao Lake, a reservoir from Zhejiang Province (eastern China), a large population of this taxon was found in down-core assemblages within 20 years of the reservoir being impounded. This abundant material allowed a better assessment of the size range and morphological variability of this species. Besides emending the description and validating the taxonomic status of this species, this study also discusses its ecology and distribution.

Keywords:

• diatom autecology
• biogeography
• subtropical deep reservoir

Acknowledgements

We acknowledge Dr. Chunhai Li from the Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, and Dr Kai Li from Zhejiang Normal University for their assistance in obtaining the sediment cores.

Disclosure statement

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

Additional information

Funding

This work was financially supported by the Basic Public Welfare Research Project of Zhejiang Province (grant number LY20D010003). Patrick Rioual acknowledges his current support from the National Natural Science Foundation of China (grant number 41888101) and previous support from the Strategic Priority Research Program of the Chinese Academy of Sciences Key Project (grant number XDB 26000000).