Schizomeris Kützing is a filamentous alga without ramifications and with differentiated basal attachment system. The genus contains the type species Schizomeris leibleinii Kützing and the two poorly known species S. irregularis Fritsch & Rich and S. indicum (Ghose) Fritsch & Rich. The species are differentiated mostly by the basal attachment system type. However, the specific taxonomy of the genus is confused. Morphometrical and morphological studies were conducted in populations identified as S. leibleinii according to two approaches. In the first one, 11 populations from different localities were analyzed and in the second, two distinct populations were monthly evaluated during 11 months. Diameter of multiseriate filaments, diameter and length of cells from multi and uniseriate filaments, presence of constriction, form of filament summit, and basal system type were evaluated in both approaches. In addition, karyological studies were conducted to complement taxonomic information. Results revealed a wide morphological variation, being more accentuated among populations from different localities than in the same populations along the time, but the characteristics showed a continuous gradient. The different types of the basal system described for the species of the genus (bluntly rounded, holdfast disc, lobed and rhizoid) were found in the populations studied. These findings suggest that distinction among the three species is very fragile and cannot be supported by differentiation of the basal system or metrical characteristics. Based on present results we consider that Schizomeris is composed by a single species. Karyological analyses resulted in n = 12, differing from previous studies and some possible explanations are discussed.
Chaetophorales; karyology; morphological variation; Schizomeris leibleinii; taxonomy
