Archetypal ‘elkhorn’ coral discovered in the Pacific Ocean

Abstract

The discovery of a population of elkhorn corals in the Central Pacific Ocean has important taxonomic implications, as this distinctive colony morphology was previously known only from the endemic and critically endangered Atlantic species Acropora palmata. Phylogenetic analyses confirmed that the Pacific elkhorn coral is genetically distant from A. palmata, and most likely represents a species previously synonymized with Acropora abrotanoides. The Pacific elkhorn coral is rare, and is of particular scientific interest because it represents one morphological extreme in the dominant genus of reef-building corals. The discovery of the Pacific elkhorn coral raises a number of important general issues in relation to biodiversity conservation, as this coral would not qualify for threatened species listing under current IUCN categories and criteria despite being demonstrably rare.

Key words:

• Acropora
• conservation
• hybridization
• IUCN
• mtDNA
• nucDNA
• Pacific ‘elkhorn’ coral

Acknowledgements

We would like to thank the College of the Marshall Islands and Marshall Island Marine Resource Authority for their on-going support of our research in the Marshall Islands and the Winifred Violet Scott Estate for support. We also gratefully acknowledge the assistance of Thomas Bowling in co-ordinating Arno fieldwork, Brent Matters and Glen Dunshea for diving and collection assistance, Maria Beger and Paul Muir respectively for in situ and skeletal photographs and Marcelo Kitahara for figure preparation.