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

Published online by Cambridge University Press:  09 December 2009

Mamiko Hirose ,
Tetsuya Tochikubo  and
Euichi Hirose
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: euichi@sci.u-ryukyu.ac.jp
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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.

Keywords

calcareous spiculesCOIDidemnidaesize rangetaxonomytunicateAscidiacea
Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 90 , Issue 5 , August 2010 , pp. 1065 - 1071
Copyright
Copyright © Marine Biological Association of the United Kingdom 2009

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