Hippocampus queenslandicus Horne, 2001 – a new seahorse species or yet another synonym?
Peter R. Teske A D , Sara A. Lourie B , Conrad A. Matthee C and David M. Green BA Molecular Ecology and Systematics Group, Botany Department, Rhodes University, Grahamstown 6140, South Africa.
B Redpath Museum, McGill University, 859 Sherbrooke St West, Montréal, Québec, H3A 2K6, Canada.
C Evolutionary Genomics Group, Zoology Department, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
D Corresponding author. Email: P.Teske@ru.ac.za
Australian Journal of Zoology 55(3) 139-145 https://doi.org/10.1071/ZO07021
Submitted: 15 April 2006 Accepted: 2 May 2007 Published: 28 June 2007
Abstract
During the past six years, 15 new seahorse species (Syngnathidae: Hippocampus) have been described on the basis of morphological characters. This approach is known to be problematic, and most species names in Hippocampus are now considered to be synonyms. Genetic methods have great potential to resolve the confused taxonomy of the genus, but none have yet been incorporated into species descriptions. In the present study, mitochondrial control region and cytochrome b DNA sequences, as well as morphological data from the recently described Queensland seahorse, Hippocampus queenslandicus Horne, 2001, were compared with corresponding data from closely related seahorse species to determine whether there is strong support for distinction of this taxon. The haplotypes of H. queenslandicus were nested among haplotypes belonging to two of the three major Southeast Asian lineages of H. spinosissimus Weber, 1913. Although incomplete lineage sorting characteristic of very recently diverged species cannot be ruled out, the genetic results suggest that H. queenslandicus is paraphyletic. Morphometric analysis further fails to provide strong support for the species status of H. queenslandicus. We conclude that support for the distinctness of H. queenslandicus is weak, and indicate that it is a synonym of H. spinosissimus. The taxonomic validity of other recently described seahorse species should be similarly scrutinised using combined genetic and detailed morphological methods.
Acknowledgements
We are grateful to Paul Southgate, Martin Hicks, Sam McCulloch and Jeff Johnson for providing specimens of H. queenslandicus. Additional seahorse samples used in this study were contributed by Choo Chee Kuang, Sesh Serebiah, Monruedee Chaiyapu and the Project Seahorse collection at the Redpath Museum. Thanks also to Stan Weitzman for advice on statistical methods, and to two anonymous reviewers for their comments on earlier versions of the manuscript. This study was supported by an ex gratia bursary from the Harry Crossley Foundation and a Claude Harris Leon Foundation postdoctoral research fellowship awarded to PT, a McGill Major Scholarship awarded to SL, an NSERC Discovery grant to DG, Project Seahorse, the National Research Foundation, the University of Stellenbosch and Rhodes University.
Bernardi, G. , Sordino, P. , and Powers, D. A. (1993). Concordant mitochondrial and nuclear DNA phylogenies for populations of the teleost fish Fundulus heteroclitus. Proceedings of the National Academy of Sciences of the United States of America 90, 9271–9274.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Chenoweth, S. F. , and Hughes, J. M. (2003). Oceanic interchange and non-equilibrium population structure in the estuarine dependent Indo-Pacific tasselfish, Polynemus sheridani. Molecular Ecology 12, 2387–2397.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Fricke, R. (2004). Review of the pipefishes and seahorses (Teleostei: Syngnathidae) of New Caledonia with descriptions of five new species. Stuttgarter Beiträge zur Naturkunde Serie A (Biologie) 668, 1–66.
Hillis, D. M. (1987). Molecular versus morphological approaches to systematics. Annual Review of Ecology and Systematics 18, 23–42.
| Crossref | GoogleScholarGoogle Scholar |
Kuiter, R. H. (2001). Revision of the Australian seahorses of the genus Hippocampus (Syngnathiformes: Syngnathidae) with a description of nine new species. Records of the Australian Museum 53, 293–340.
Lourie, S. A. , Green, D. M. , and Vincent, A. C. J. (2005). Dispersal, habitat differences, and comparative phylogeography of southeast Asian seahorses (Syngnathidae: Hippocampus). Molecular Ecology 14, 1073–1094.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Miya, C. M. , and Nishida, M. (1997). Speciation in the open ocean. Nature 389, 803–804.
| Crossref | GoogleScholarGoogle Scholar |
Piacentino, G. L. M. , and Luzzatto, D. C. (2004). Hippocampus patagonicus sp. nov., nuevo caballito de mar para la Argentina (Pisces, Syngnathiformes). Revista del Museo Argentino de Sciencias Naturales, N.S. 6, 339–349.
Saitou, N. , and Nei, M. (1987). The neighbour-joining method: a new method of reconstructing phylogenetic trees. Molecular Biology and Evolution 4, 406–425.
| PubMed |
Teske, P. R. , Cherry, M. I. , and Matthee, C. A. (2003). Population genetics of the endangered Knysna seahorse, Hippocampus capensis. Molecular Ecology 12, 1703–1715.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Teske, P. R. , Cherry, M. I. , and Matthee, C. A. (2004). The evolutionary history of seahorses (Syngnathidae: Hippocampus): molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean. Molecular Phylogenetics and Evolution 30, 273–286.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Teske, P. R. , Hamilton, H. , Palsbøll, P. J. , Choo, C. K. , Gabr, H. , Lourie, S. A. , Santos, M. , Sreepada, A. , Cherry, M. I. , and Matthee, C. A. (2005). Molecular evidence for long-distance colonization in an Indo-Pacific seahorse lineage. Marine Ecology Progress Series 286, 249–260.