A Comparative Study of the Morphological Characters and Sequence Data of rbcL Gene in Cosmarium Species

Algae > Volume 16(4); 2001 > Article

Algae 2001;16(4): 349-361.

Mira Nam, Ok-Min Lee

Department of Biology, Kyonggi University

ABSTRACT

Cosmarium is one of the earlist described genera of the placoderm desmids, and one of the largest genera, including over 1,000 species. In this genus, species are traditionally grouped into sections according to the wall features and the shape of semicells. Sequence data for the large subnuit of RUBISCO (rbcL) was employed to compare with the section system of this genus based on morphological characters. Parsimony analysis of the rbcL sequences data representing 18 taxa, with all positions and changes weighted equally, did not agree with the section system except for a few sections. According to current sequence analysis, most taxa in section I were shown to be in a same clade with those in section II, which were classified by the wall features. Most taxa in section A through F, the system based on the shape of semicells, also turned out to be in a same clade with taxon of another section. Therefore, further study was suggested in the morphological characters of genus Cosmarium.

Key words: maximum parsimony analysis, placoderm desmids, semicell