Frenguelli's vast work and his collections (from Argentina, Bolivia, Chile, Peru, Uruguay, Egypt, Somalia and Antarctica) constitute a primary reference for those who undertake the study of the South American diatom flora and / or work on taxonomic and / or nomenclatural revisions of genera, species, varieties and forms erected by the author.
The protologues are in the original language, Spanish or Italian, in order to avoid possible translation problems, accompanied by Latin diagnoses or descriptions, if available. Arrangement of taxa is alphabetically by names given by Frenguelli, without consideration of subsequent taxonomic or nomenclatural changes. In this catalogue are included new taxa: genera, species, varieties and forms. New combinations and the new names given by Frenguelli in the taxonomic and nomenclatural remarks are given only if they are linked to a new taxon of the author. Excluded are all suprageneric taxa, most of which had already been described by other authors as groups or subgenera and that are not linked to Frenguelli's type material.
The 421 taxa described by Frenguelli and included in this catalogue had been published originally in 38 different papers which are listed and consecutively numbered in this book.