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The concept of Taxonomic Harmonisation (TH) incorporates the search for similarities between taxa mentioned in different data sets and/or taxonomic classification systems, in order to propose a more coherent and homogenous taxonomic system necessary for practical usage in basic and applied scientific activities. For the present project we conceived Fabaeformiscandona tricicatricosa as a species defined by a homeostatic cluster of traits with a given temporal persistence, visible in close relationship with other Fabaeformiscandona species, like F. caudata (Kaufmann), F. levanderi (Hirschmann), and F. siliquosa (Brady), as well as with Candona neglecta Sars which displays analogies in valve shape. We show the advantages to study the above-mentioned taxa by a combination of classic observations in optical microscopy with SEM-techniques and with the treatment of data using geometric morphometrics and multivariate statistics. A protocol for the implementation of the TH of F. tricicatricosa is proposed. We offer a differential diagnosis for F. tricicatricosa as compared to F. caudata, F. levanderi, F. siliquosa and C. neglecta. We use for taxonomic diagnostics a combination of aggregate traits like the average of the outline of valves and qualitative traits, like the shape and the position of a ledge on the posterior side of the valves. We propose to add the term “Consensus” to the species defined by the procedure of the taxonomic harmonisation. To differentiate them from other types of species we propose to use the extension sensu lato following the Linnean species notation. Comments on the origin and the (palaeo)ecology and (palaeo)biogeography of F. tricicatricosa are presented.