Taxonomic significance of micromorphology and dimensions of oospores in the genus Chara L., Charales, Chlorophyta

Oospore wall ornamentation patterns as revealed by scanning electron microscopy (SEM) provide important taxonomic characters in the Charales. The present study illustrates inter- and intra-specific variations in the oospore wall ornamentation of five species of Chara, including eight intra-specific taxa. The type variety and form of C. globularis shows pusticular elevations with pores at the base of the elevation. The variety and form aspera of C. globularis shows a porous oospore wall, and the oospore is provided with a ribbon which bears nearly granular ornamentation. The type form of C. setosa has a granular oospore wall. The three forms of C. braunii show a similar type of ornamentation and support their placement under a single species. Chara corallina has a roughened oospore wall. Oospore dimensions studied at the population level are another feature included in the present study. The oospore dimension data (length, width fossa-breadth, number of striae) at the population level were analyzed statistically, and the results show species-specificity of these parameters. The significance of oospore wall ornamentation and dimensions are discussed simultaneously with morphological features