Phylogenetic and geographic variation of northern Australian sympatric lineages of Treptopale homalos and T. paromolos (Annelida: Phyllodocida: Chrysopetalidae) using mitochondrial and nuclear sequences

Abstract

We used mitochondrial (COI) and nuclear (Histone H3) genome markers to test the hypothesis that the diversity of Treptopale (Annelida: Chrysopetalidae) in northern Australia comprises more than the two currently known species recently described based on morphology. The molecular phylogeny reveals nine clades. The Treptopale homalos species complex comprises: T. homalos sensu stricto, the only clade occurring all around northern Australia (from Heron Island to Ningaloo Reef); Clade 8 found only at Ningaloo Reef; Clade 2 found only on the Great Barrier Reef and described here as new. Treptopale magdae sp. nov. can be distinguished morphologically by the smaller number of internal ribs of the lateral, main and medial paleael notochaetae. The diverse Treptopale paromolos species complex comprises six clades: Clade 3, Treptopale paromolos sensu stricto and Clade 5 are only found on Australia's NW coast; Clades 4, 6 and 9 are found only in NE Australia. Molecular phylogenetic relationships, especially those using mtDNA COI, suggest that Australian east and west coast populations of the T. homalos and T. paromolos lineages have diverged a number of times. The highest diversity of Treptopale clades is found within the complex micro-patch habitats of NE and NW Australia's major coral reef systems. The low diversity of Treptopale clades found in the north (Darwin Harbour) and northwest (Scott Reef) is related to the presence of less complex reefal systems and a corresponding lack of coral habitat diversity.

Keywords:

• mitochondrial DNA COI
• Histone H3
• systematics
• phylogeography
• polychaete
• new taxon

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank Dr Chris Glasby of Museum & Art Gallery of the Northern Territory for assistance and collaboration during the CReefs project. Material from Heron Island, Lizard Island and Ningaloo was collected under the auspices of the CReefs project organised by the Australian Institute of Marine Science (AIMS). This project is sponsored by BHP Billiton in partnership with the Great Barrier Reef Foundation, AIMS and the Alfred P. Sloan Foundation. CReefs is also a field programme of the Census of Marine Life. We acknowledge Julian Caley and Shawn Smith (AIMS) for their excellent organization and field support at all three Australian reefs sampled. An ABRS/CReefs grant enabled Charlotte Watson to receive funding for three years to work up the family Chrysopetalidae at the Museum and Art Gallery of the Northern Territory and funded Nu-Wei V. Wei for a similar period to undertake molecular analysis of CReefs polychaetes at Charles Darwin University.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark