A response to ‘Comment to Wetzeliella and its allies – the ‘hole’ story: a taxonomic revision of the Paleogene dinoflagellate subfamily Wetzelielloideae by Williams et al. (2015)’

ABSTRACT

The paper by Williams et al. (2015) concerning a proposed taxonomic revision of the subfamily Wetzelielloideae has led to a comment by Bijl et al. (2016) that questions the validity of our assumptions regarding recognition of the equiepeliform, latiepeliform, hyperepeliform and soleiform archaeopyle types and their significance at the generic level. In this response we address the points that they raise, which are: the introduction of taxonomic criteria allegedly not followed in other fossil subfamilies; the erection of too many taxa; the unworkable nature of the proposed classification; and the reduction of stratigraphic applicability of many significant marker species. We have organised our response under the following topics: pragmatism versus theory; generic criteria: intergroup consistency; the genus Apectodinium and operculum attachment; stratigraphic utility; the number of taxa; and recognition problems. We also discuss specimens illustrated in the two plates included with the comment. The variations in archaeopyle shapes and types of attachment of the operculum (the latter concept has been modified following more recent research) that we have used in part to separate the genera within the Wetzelielloideae have been previously applied to other peridiniacean subfamilies, most notably the Deflandreoideae. As with that subfamily, we consider that our focus on archaeopyle shape and operculum attachment for differentiating wetzelielloidean genera introduces an approach that may help refine the stratigraphic ranges of individual species. While it is a fundamental truth that there are no ‘correct’ taxonomic ideas, we consider that new approaches should be tested with usage over time, not rejected out of hand prior to careful study.

KEYWORDS:

• Biostratigraphy
• dinoflagellate cysts
• evolution
• Paleogene
• taxonomy
• wetzelielloideans

Acknowledgements

We thank Alina Iakovleva for ongoing and stimulating discussion on wetzelielloidean dinoflagellate cysts. Thanks are due also to Daniel Michoux for allowing us to quote his comment from his review of Bijl et al. (2016). We thank Alina and Daniel, as well as Peta Mudie, also for reviewing this manuscript. This is ESS Contribution No. 20160306.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Graham L. Williams

GRAHAM WILLIAMS's main field of interest is mesozoic-cenozoic palynostratigraphy of offshore eastern Canada, including arctic areas. His interest in dinoflagellates has led to studies of these palynomorphs in both hemispheres, including the deep ocean basins. After seven years at Pan American Petroleum Corporation (for anyone who remembers that far back), Graham joined the Geological Survey of Canada in 1971. He has spent the last 43 years at Bedford Institute of Oceanography in Nova Scotia, where he has the good fortune to work with some outstanding colleagues.

Sarah P. Damassa

SARAH PIERCE DAMASSA, in a previous existence, was a palaeogene dinoflagellate specialist, having studied with Bill Evitt, Al Loeblich and Helen Loeblich. She then worked as a consulting palynologist for around fifteen years. A career change then led her to Lexington, Massachusetts, where she taught Environmental Earth Science to ninth-grade students for twenty years. She has also coached the school's National Ocean Science Bowl team for twelve years. Thanks to her co-authors, she has managed to retain a tenuous toehold in the world of fossil dinoflagellates, and has thoroughly enjoyed working with them on the Wetzeliella paper.

Robert A. Fensome

ROB FENSOME, like Graham, works for the Geological Survey of Canada in their Atlantic Division at the Bedford Institute of Oceanography, Dartmouth, Nova Scotia. During his 33-year tenure at GSC, Rob has focussed mainly on the mesozoic-cenozoic dinoflagellate cysts from off Canada's east coast, but is now venturing into projects involving assemblages from northwestern and Arctic Canada. While biostratigraphic and paleoenvironmental studies justify his paycheck, he also has a strong interest in dinoflagellate evolution.

G. Raquel Guerstein

G. RAQUEL GUERSTEIN is a professor at the Universidad Nacional del Sur in Bahıa Blanca, Argentina, and a scientific researcher of the Consejo Nacional de Investigaciones Cientıficasy Tecnicas (Conicet). She graduated in geological oceanography from the Universidad Nacional del Sur, Argentina and received her PhD degree in geology in 1987 from the same university. She studies organic-walled dinoflagellate cyst assemblages from various sedimentary basins in Argentina. Her research interests are focused on the climatological and paleoceanographical evolution of the Southern and South Atlantic oceans during the transition from greenhouse to icehouse conditions during the Cenozoic.