Synonyms are flagged on the taxonomic displays by red font. From those synonyms, hyperlinks labeled "(syn)" lead to the valid taxa. Hyperlinks shown as "synonyms" by valid taxa lead to lists of synonyms.

For example, clicking "synonyms" next to "auritum" in this display, would show which taxa are synonyms of Mecynostomum auritum:

while clicking on the hyperlink labeled "(syn)" next to "arenarium" shows the valid taxon for that synynonym: