Abstract
Polystichum Roth is one of the largest and most taxonomically challenging fern genera. South American species have a rich and complex nomenclatural history; many of the early names are inadequately typified. Based on extensive examination of original type material, we designate eleven lectotypes (including Aspidium mohrioides, Aspidium montevidense f. imbricata, Aspidium montevidense f. squamulosa, Aspidium plicatum, Aspidium pycnolepis, Dicksonia andina, Polystichum elegans, Polystichum mohrioides f. latifolia, Polystichum multifidum var. autranii, Polystichum platyphyllum var. kurtziana, and Polypodium polystichoides), and one neotype (Polystichum brongniartianum) for Polystichum taxa. Furthermore, three new synonyms are proposed.