A new genus of Eunotiales (Bacillariophyta, Bacillariophyceae: Peroniaceae), Sinoperonia, from Southeast Asia, exhibiting remarkable phenotypic plasticity with regard to the raphe system

Abstract:

We describe Sinoperonia gen. nov. for freshwater diatoms from mountainous regions of south-central China and northern Vietnam, whose single species, S. polyraphiamorpha sp. nov., develops monoraphid, biraphid and araphid frustules in the general proportions of 4:2:1 (China) or 2:1:1 (Vietnam), respectively, in different populations. Light and scanning electron microscope observations of this species show that raphe-bearing valves also have rimoportulae, and thus it is assigned to the Eunotiales. The raphe-bearing valves have the raphe at or near the middle of the valves, suggesting a placement in the Peroniaceae, and this new diatom is compared with the two other genera, Peronia and Actinellopsis, in this small but phylogenetically important group. We discuss the extreme morphological variation in this new taxon, and the growing body of evidence that the freshwater diatom flora of Southeast Asia may harbour many endemic genera as well as species.

Key Words::

• Actinellopsis
• China
• Freshwater
• Peronia
• Phylogeny
• Raphe
• Scanning electron microscope
• Sinoperonia
• Vietnam

ACKNOWLEDGEMENTS

The authors thank Dr Carlos Wetzel for his helpful discussions on the diversity of forms in Eunotiales. Two anonymous reviewers offered helpful, critical comments on the manuscript. This work was supported by the National Science Foundation of China (nos. 31670201 & 31470308), National Science Foundation of Heilongjiang Province (no. C2015021) and Russian Science Foundation (14-14-00555) for MK and AG.