Structure and elemental composition of pellicular warts of Euglena spirogyra (Euglenophyceae)

Abstract

The cellular surface of Euglena spirogyra (Ehrbg.) can be variously ornamented with mineralized protuberances termed pellicular warts. In this study using light and electron microscopy and energy-dispersive X-ray spectroscopy, the structure and elemental composition of warts of E. spirogyra cells were analysed. The data show the warts to be tiered aggregations of mucilage-associated, predominantly iron-enriched granules that form regularly spaced mases overlying the ridges of helically arranged pellicular striae. Wart morphology, substructure and elemental composition are described and discussed in the light of their possible systematic and phylogenetic implications for their species. Some features of the wart mineralization process are also compared with similar extracellular biomineralizing events in other euglenoids.