Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-08T07:30:39.156Z Has data issue: false hasContentIssue false

Taxonomic significance of tunic spicules in photosymbiotic ascidians: a quantitative and molecular evaluation

Published online by Cambridge University Press:  09 December 2009

Mamiko Hirose
Affiliation:
Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan
Tetsuya Tochikubo
Affiliation:
Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan
Euichi Hirose*
Affiliation:
Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan
*
Correspondence should be addressed to: E. Hirose, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara Okinawa 903-0213, Japan email: [email protected]

Abstract

Many didemnid ascidians have calcareous spicules in the tunic. Since the spicules of each species have a specific shape and size-range, they are often regarded as an important character for taxonomy. To evaluate the taxonomic significance of tunic spicules, a quantitative survey of spicule size and shape was combined with a molecular phylogeny inferred from the partial sequence of the cytochrome c oxidase subunit I (COI) gene in some groups of didemnid species that are supposedly closely related. This study revealed the presence of substantial intraspecific variations in the shape and size of tunic spicules. The spicules are, therefore, not always crucial features discriminating species, particularly among related species. Although tunic spicules are potentially valuable features for didemnid taxonomy, their intraspecific variation should be carefully considered before they are used as a key character for species identification.

Type
Research Article
Copyright
Copyright © Marine Biological Association of the United Kingdom 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Dias, G.M., Abreu, A.G., Silva, F. and Solferini, V.N. (2009) Microgeographical differentiation between morphotypes of Trididemnum orbiculatum (Tunicata: Ascidiacea) in southeastern Brazil. Aquatic Biology 4, 243252.Google Scholar
Hirose, E., Kamijoh, A. and Oka, A.T. (2007) Distribution of the photosymbiotic ascidians in Chichijima Island (Ogasawara Islands, Tokyo). Biological Magazine Okinawa 45, 39.Google Scholar
Hirose, E. and Oka, A.T. (2008) A new species of photosymbiotic ascidian from the Ryukyu Archipelago, Japan, with remarks on the stability of stigma number in photosymbiotic Diplosoma species. Zoological Science 25, 12611267.Google Scholar
Hirose, E., Oka, A.T. and Hirose, M. (2009a) Two new species of photosymbiotic ascidians of the genus Diplosoma from the Ryukyu Archipelago with partial sequences of the COI gene. Zoological Science 26, 362368.Google Scholar
Hirose, M., Yokobori, S. and Hirose, E. (2009b) Potential speciation of morphotypes in the photosymbiotic ascidian Didemnum molle in the Ryukyu Archipelago, Japan. Coral Reefs 28, 119126.Google Scholar
Hirose, M. and Hirose, E. (2009) DNA barcoding in photosymbiotic species of Diplosoma (Ascidiacea: Didemnidae), with the description of a new species from the southern Ryukyus, Japan. Zoological Science 26, 564568.Google Scholar
Jobb, G. (2008) TREEFINDER, version October 2008. Munich, Germany. www.treefinder.deGoogle Scholar
Kott, P. (2001) The Australian Ascidiacea, part 4, Aplousobranchia (3), Didemnidae. Memoirs of the Queensland Museum 47, 1408.Google Scholar
Kott, P. (2004) A new species of Didemnum (Ascidiacea, Tunicata) from the Atlantic coast of North America. Zootaxa 732, 110.Google Scholar
Lambert, G. (2009) Adventures of a sea squirt sleuth: unraveling the identity of Didemnum vexillum, a global ascidian invader. Aquatic Invasions 4, 528.Google Scholar
Lewin, R.A. and Cheng, L. (1989) Prochloron, a microbial enigma. New York: Chapman & Hall.Google Scholar
Monniot, C. and Monniot, F. (1987) Les ascidies de Polynésie française. Mémoirs du Muséum National d'Historie Naturelle Paris 136A, 1155.Google Scholar
Monniot, C., Monniot, F. and Laboute, P. (1991) Coral reef ascidians of New Caledonia. Paris: ORSTOM.Google Scholar
Monniot, F. and Monniot, C. (2001) Ascidians from the tropical western Pacific. Zoosystema 23, 201383.Google Scholar
Oka, A.T., Suetsugu, M. and Hirose, E. (2005) Two new species of Diplosoma (Ascidiacea: Didemnidae) bearing prokaryotic algae Prochloron from Okinawajima (Ryukyu Archipelago, Japan). Zoological Science 22, 367374.Google Scholar
Posada, D. and Crandall, K.A. (1998) Modeltest: testing the model of DNA substitution. Bioinformatics 14, 817818.Google Scholar
Sambrook, J., Fritsch, E.F. and Maniatis, T. (1989) Molecular cloning: a laboratory manual. New York: Cold Spring Harbor Laboratory Press.Google Scholar
Swofford, D. (2003) PAUP* 4.0b7a — Phylogenetic analysis using parsimony (*and other methods). Sunderland, MA: Sinauer Associates.Google Scholar
Thompson, J.D., Higgins, D.G. and Gibson, T.J. (1994) ClustalW: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Research 22, 46734680.Google Scholar
Turon, X. (1986) Morfología de las espículas en las especies de la familia Didemnidae (Ascidiacea) del litral de Cataluña e Islas Baleares. Miscelánea Zoológica 10, 213222.Google Scholar