A new species, Myrianida paredesi, and new records of Myrianida pentadentata (Imajima, 1966), and Procerarea micropedata (Hartmann-Schöder, 1962), are described from the central coast of Peru. Myrianida paredesi is characterized by the presence of an additional mid-dorsal, digitiform structure, quite similar to a dorsal cirrus (unique among all syllids), a subtriangular prostomium with a posterior region extended to middle peristomium, pharynx with a single elongated sinuation and a trepan with 14–15 equal teeth in a single ring. Descriptions of male and female stolons are also provided. The phylogenetic position of the new species within Myrianida is determined using molecular data, suggesting it is closely related to the species that share the presence of one ciliary troch per segment (except M. pachycera; unknown in M. australiensis), moderate number of equal teeth on trepan (except M. pachycera), and the mode of reproduction.

Descriptions of the collected specimens of Myrianida pentadentata (Imajima, 1966), and Proceraea micropedata (Hartmann-Schröder, 1962), both new reports to Peru, are also included.

This paper deals with a new species of Myrianida collected from Rhodes Island at 1 m depth among algae in April 2014. This new species is mainly characterized by having flattened dorsal cirri; high number of falcigers in parapodia; a trepan with 16 unequal teeth; and a brownish patch (in fixed specimen) on dorsum of each segment. Individuals are at the stage of reproduction, with developing stolons.