A Comparative Study of Morphological Characters and Sequences of rbcL Gene in Staurastrum of Desmid

Algae > Volume 16(4); 2001 > Article

Algae 2001;16(4): 363-367.

Mira Nam, Ok-Min Lee

Department of Biology, Kyonggi University

ABSTRACT

The genus Staurastrum Meyen includes more recoreded species and subspecific taxa than any of the desmids except Cosmarium. Because of the great morphological variations exhibited by radiate semicells, workers proposed subdivisions of Staurastrum to form either separate genera, or subgenera. This genus has been assigned to two divisions, with sections in each, based on the elongated processes at angles of semicells, the morphology of semicell, the sculpture of cell wall and the shape of sinus. Sequence data for the large subnuit of RUBISCO(rbcL) were employed to compare with taxa of two divisions, with sections in each, for evaluating the taxonomic stability of these morphological characters. Parsimony analysis of the rbcL data, with all positions and changes weighted equally, was consistant with two divisions of this genus, but not with sections. Therefore, it is believed that the feature of the elongated processes at angles of semicells was a character reflecting the phylogenetic relationships in genus Staurastrum. The morphology of semicell, the sculpture of cell wall and the shape of sinus, which devided each division to sections, are not appropriate characters to be used in section system.

Key words: desmid, phylogeny, rbcL, Staurastrum