Diatoms of the northeastern Gulf of Mexico: Vallithidium (Achnanthales: Achnanthidiaceae), a new monoraphid genus based on Navicula marginulata Cleve

Abstract

While conducting a systematic investigation of phytoplankton assemblages in the northeastern Gulf of Mexico (GOM) in the aftermath of the Deepwater Horizon blowout we took the opportunity to collect sediment samples from off the coast of Pensacola Bay, Florida. These samples contained sufficient numbers of a monoraphid diatom initially identified as Achnanthes controversa Hustedt (Navicula marginulata Cleve) to examine its fine structure in detail. The results of these investigations clearly show that this taxon could not be accommodated in Achnanthes as currently understood, or in any currently described genus in the Achnanthidiaceae. We, therefore, propose a new genus, Vallithidium, with Vallithidium marginulatum (Cleve), J.A. Nienow & A.K.S.K Prasad as the generitype. Our investigations also show that the taxon Hustedt illustrated from Campeche Bay is not the same as the taxon described from the northeastern Gulf. We therefore describe it as a separate species in the new genus, Vallithidium campechianum sp. nov.

Keywords:

• Achnanthes controversa
• Vallithidium
• Gulf of Mexico
• Achnanthidiaceae
• marine benthic diatoms

Acknowledgments

This research was funded by grants from the BP/FIO Research Initiative to Dr. S. Wise (Florida State University, FSU) and the BP/Gulf of Mexico Research Initiative through DEEP-C: Deep Sea to Coast Connectivity in the Eastern Gulf of Mexico to Drs. F. Coleman and E. Chassignet (FSU). We would also like to thank the captain and crew of the R/V Bellows for their assistance in collecting samples. Special thanks to Drs. S. Wise (FSU), R. Snyder (University of West Florida (UWF)), W. Jeffrey (UWF), Valdosta State University graduate students A. Adhikari and H. Malik, for help with collecting and processing samples, to Ms. Genevieve E. Tocci, Senior Curatorial Technician in the Farlow Herbarium Diatom Collection, Harvard University Herbaria or her help in locating materials, and to Dr. Richard L. Moe (University and Jepson Herbaria, UC Berkeley) for nomenclatural advice and clarifications.

Disclosure statement

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

Additional information

Funding

This work was supported by BP/Gulf of Mexico Research Initiative; BP/FIO Research Initiative.