Hydrolithon braganum sp. nov. (Corallinaceae, Rhodophyta), the first known exclusively fossil semi-endophytic coralline red alga

Abstract

Woelkerling W.J., Bassi D. and Iryu Y. 2012. Hydrolithon braganum sp. nov. (Corallinaceae, Rhodophyta), the first known exclusively fossil semi-endophytic coralline red alga. Phycologia 51: 604–611. DOI: 10.2216/11-119.1

Hydrolithon braganum sp. nov., the first known exclusively fossil semi-endophytic species of Corallinaceae (Corallinales, Rhodophyta), is based on material from Integrated Ocean Drilling Program Expedition 310 cores of last deglacial age [c. 20,000–10,000 years before present] from reef terraces around Tahiti, French Polynesia. A detailed morphological–anatomical account is provided and morphological–anatomical similarities to other species are discussed. The taxonomic position of H. braganum is problematic in relation to recent proposals for changes to the circumscription of Hydrolithon. Evidence is presented to show that the morphological–anatomical criteria proposed in recent molecular-based studies are untenable for circumscribing genera called Hydrolithon and Porolithon. Thus, pending further research, the two genera are best treated as the Hydrolithon–Porolithon complex with Hydrolithon having nomenclatural priority, being polyphyletic, and encompassing one or several cryptic genera distinguishable on presently known molecular criteria but not distinguishable using presently known morphological–anatomical criteria.

Key Words::

• Corallinaceae
• Fossil coralline red alga
• Hydrolithon
• IODP Expedition 310
• Porolithon
• Semi-endophytic

ACKNOWLEDGEMENTS

We thank Don Enrico Peverada (Ferrara) for the Latin translation. DB thanks the Graduate School of Environmental Studies, Nagoya University, Japan. We thank two anonymous reviewers and the Editor-in-Chief for providing helpful comments on the manuscript. We are grateful to the Integrated Ocean Drilling Program for inviting one of the authors (YI) to participate in IODP Expedition 310. Thanks also are due the scientists of Expedition 310, the staff of European Consortium for Ocean Research Drilling Science Operator, the drillers from Seacore Ltd (Cornwall, UK), and Captain William Roger and crew of the DP Hunter for their cooperation. The Bremen Core Repository staff members, especially Walter Hale, Ursula Röhl, and Alex Wulbers, are acknowledged for their support of the Onshore Science Party. This research made use of samples and data provided by the IODP.