Morphology of three benthic diatoms from a tropical mangrove in Hainan Island, China: Gyrosigma centropunctatum sp. nov., G. dongzhaiense sp. nov. and G. orbitum Thaler et Kaczmarska

Abstract

Three benthic Gyrosigma species isolated from sediments of a tropical mangrove in Hainan Island, China, are described using light, scanning and transmission electron microscopy: G. centropunctatum sp. nov., G. dongzhaiense sp. nov. and G. orbitum Thaler et Kaczmarska. Gyrosigma centropunctatum is a tube-dwelling species possessing a unique row of pores on either side of the central area. Gyrosigma dongzhaiense differs from congeners by a combination of small cell size, linear-sigmoid outline, and higher stria density. Gyrosigma orbitum is another tube-dwelling species, which possesses two remarkable oval pits on the external central area. This study expands our knowledge of the marine species diversity and distribution of Gyrosigma in the tropical Western Pacific. We discuss the taxonomic significance of tubes in the species identification of Gyrosigma.

Keywords:

• Gyrosigma
• diatom
• new species
• tropical mangrove
• sediment

Acknowledgements

The authors are grateful to Dr Anton Igersheim (Natural History Museum Vienna, Austria) for providing the original sketch of Pleurosigma spenceri var. exilis in Grunow’s collection and Prof. Bart Van de Vijver (Meise Botanic Garden, Belgium) for searching the material and slides. The authors also thank Hitachi High-Tech Science Park Shanghai Lab for allowing us to use the Hitachi Regulus 8240 SEM.

Disclosure statement

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

Additional information

Funding

This work has been supported by the National Natural Science Foundation of China [grant number 31800171], the Strategic Priority Research Program of Chinese Academy of Sciences [grant number XDB42000000] and the CAS President’s International Fellowship for Visiting Scientists [grant number 2018VBA0035].