Chara zeylanica (Klein ex Willdenow) R.D.Wood is known
to develop populations which display either four- or eight-scutate antheridia.
Despite only minor differences in the vegetative features, plants with these
two types of male gametangia proved to be reproductively isolated and
C. haitensis Turpin was validated as the correct name
for the octoscutate plants (Proctor et al. 1971). Here
we provide data for the calcified female reproductive organs (gyrogonites) of
both species in order to determine whether they can be distinguished or not.
Ten populations from both field collections and culture material were studied.
The morphological characteristics of the gyrogonites were determined on the
basis of measurements of 100 specimens for each population. The gyrogonites of
four- and eight-scutate plants proved to be significantly different and thus
enhanced separation at species level. Ecology, biogeography and the possible
phylogenetic relationships of the taxa are discussed. Unlike
C. zeylanica, which displays worldwide distribution
within the tropical belt, the modern distribution of
C. haitensis seems hitherto restricted to the American
continent. Within this area, C. zeylanica grows
preferentially in permanent lakes whereas C. haitensis
is only found in temporary water bodies. Given these different ecological
requirements, the fossil record of both taxa, determined from their specific
gyrogonite morphology, can provide information about the nature of ancient
lake-ecosystems particularly useful for Quaternary studies in the Americas.