The structure of Melosira sulcata (Ehr.) Kütz. var. sulcata frustules from Lower Oligocene diatomites from Futoma (Carpathians, Poland)
Abstract
Budowa pancerzyków Melosira sulcata (Ehr.) Kütz. var. sulcata z dolnooligoceńskich diatomitów z Futomy (Polska)
Under the light and scanning electron microscope the three known Melosira sulcata (Ehr.) Kütz. var. sulcata types of valve face ornamentation were observed; “f. radiata”, “f. radiolata”, “f. coronata”. Fourth type unknown so far, was found and described. It is characterized by the presence of a distinct swelling in .the centre of the valve face. Significant differences were noted between frustule structure of M. sulcata and the type species for Melosira genus — M. nummuloides C. Ag. The M. sulcata frustule is composed of a single (not 3, as M. nummuloides) layers of silica, has the labiate processes on the mantle (not on the valve face); and has no girdle bands. It is more like to the M. granulata (Ehr.) Ralfs and M . arenaria Moore groups, and it is suggested that occupy an intermediate taxonomic position between them.
Under the light and scanning electron microscope the three known Melosira sulcata (Ehr.) Kütz. var. sulcata types of valve face ornamentation were observed; “f. radiata”, “f. radiolata”, “f. coronata”. Fourth type unknown so far, was found and described. It is characterized by the presence of a distinct swelling in .the centre of the valve face. Significant differences were noted between frustule structure of M. sulcata and the type species for Melosira genus — M. nummuloides C. Ag. The M. sulcata frustule is composed of a single (not 3, as M. nummuloides) layers of silica, has the labiate processes on the mantle (not on the valve face); and has no girdle bands. It is more like to the M. granulata (Ehr.) Ralfs and M . arenaria Moore groups, and it is suggested that occupy an intermediate taxonomic position between them.