Aulacoseira stevensiae sp. nov. (Coscinodiscophyceae, Bacillariophyta), a new diatom from Ho Ba Bê, Bac Kan Province, Northern Viêt Nam

Abstract

A new species of Aulacoseira Thwaites is described from piston core samples from Ho Ba Bê in the karst region of northern Viêt Nam. Although it closely resembles Aulacoaseira subborealis (Nygaard) Denys, Muylaert & Krammer, A. stevensiae Weide sp. nov. is designated a new species based mainly on morphological differences in the spines, including invariably inclined spines that are rounded, differences in the Ringleiste, areola pattern and overall size. Aulacoseira stevensiae is present throughout a core that spans the last 500 years. It was a major component of the diatom community, but the populations have recently decreased, possibly being outcompeted by Discostella Houk & Klee and Cyclotella (Kützing) Brébisson species.

Keywords:

• separation spine
• Ringleiste
• karst
• Aulacoseira subborealis
• centric diatom

Acknowledgments

This work constitutes part of a Master's Thesis. I gratefully acknowledge the assistance of Frithjof A.S. Sterrenburg, without whose help this manuscript could not have been completed. I also thank two anonymous reviewers whose feedback greatly improved this manuscript. Mr. Andreas Friedrich for translating sections of Krammer & Lange-Bertalot, and Mr. Andrew Hamilton and Mr. Richard Gossett of the Institute for Integrated Research in Materials, Environments and Society for the use of and assistance with SEM imaging. Finally, I gratefully acknowledge the help of Dr. Vu The Long, who introduced Dr. Stevens to Ho Ba Bê and coordinated the 2004 coring expedition. This work was supported by the University of Nebraska under the Nebraska Experimental Program to Stimulate Competitive Research (EPSCoR); The Paleontological Society under the G. Arthur Cooper Student Award; International Phycological Society under the Student Research Grant; Geological Society of America under the Graduate Student Research Grant; Los Angeles Basin Geological Society under the Student Research Scholarship.

Disclosure statement

No potential conflict of interest was reported by the author.