Cytological and taxonomic studies of the Euglenales. II. Comparative microarchitecture and cytochemistry of envelopes of Strombomonas and Trachelomonas

Abstract

Envelopes of Strombomonas conspersa, like those of Trachelomonas, may range in colour from hyaline to dark brown. Cytochemical staining with Alcian Blue reveals differences between light and dark envelopes of both genera: acidic and sulphated glycosaminoglycans (mucopolysaccharides) are present in all the organic matrices; however, in dark envelopes the sulphate groups are masked by the Mn and are detectable only when the metal is removed. The TEM and EM-EDS comparative studies of the microarchitecture and elemental composition of envelopes of Strombomonas conspersa and several species of Trachelomonas show similar results: hyaline envelopes are characterized by unmineralized strands that anastomose to form a complex reticulum, whereas dark envelopes, heavily mineralized with Mn, are composed of dense needle-like components enmeshed in a mucilaginous matrix. In the light of these findings, we propose that Strombomonas conspersa be removed to its original taxonomic position in the genus Trachelomonas, as T. conspersa Pascher.