Morphology, molecular phylogeny and taxonomy of Nitella comptonii (Charales, Characeae)

Abstract

H. Sakayama, S. Arai, H. Nozaki, F. Kasai and M.M. Watanabe. 2006. Morphology, molecular phylogeny and taxonomy of Nitella comptonii (Charales, Characeae).Phycologia 45: 417–421. DOI: 10.2216/05-31.1

The taxonomic status of Nitella comptonii (Charales, Characeae) is not well understood because this species has not been recorded since the early 20th century, and detailed examinations of fully mature individuals have not been performed. Recently, we collected fully mature N. comptonii from the Okinawa Islands in Japan. These exhibited a distinctive fertile spherical head in the axils, and their vegetative and reproductive structures were consistent with those in the original description of the species. In 1965 in his ‘A revision of the Characeae’, R. D. Wood assigned N. comptonii as a subspecies of N. pseudoflabellata. In our study, scanning electron microscopic analysis of N. comptonii oospores revealed that external and internal oospore morphology of N. comptonii was clearly different from that of N. pseudoflabellata. In addition, multiple DNA phylogeny using the concatenated sequences of the chloroplastrbcL,atpB, andpsaB genes, and nuclear 5.8S ribosomal RNA gene and internal transcribed spacer regions, clearly separated N. comptonii from N. pseudoflabellata. Therefore, N. comptonii should be classified as a separate species.

Key Words::

• atpB gene
• Charales
• Charophyceae
• Internal transcribed spacer region
• Japanese taxa
• Morphology
• Nitella comptonii
• Oospores
• psaB gene
• rbcL gene
• Scanning electron microscopy
• Taxonomy

ACKNOWLEDGMENTS

This study was conducted as a part of the Time Capsule Project at NIES and supported in part by a Grant-in-Aid for Scientific Research (No. 15651102 to H.N.) from the Japan Society for the Promotion of Science.