Phenotypic similarity leads to taxonomic inconsistency: A revision of the lowland's antpittas

A comprehensive molecular phylogeny of lowland antpittas in the genera Hylopezus and Myrmothera indicated that Hylopezus, as currently defined, is paraphyletic with respect to Myrmothera and Grallaricula. Specifically, both species now placed in Myrmothera, Hylopezus dives, Hylopezus fulviventris and Hylopezus berlepschi form a strongly supported clade that is sister to a clade comprised by Hylopezus perspicillatus, Hylopezus auricularis, Hylopezus ochroleucus, Hylopezus whittakeri, Hylopezus paraensis, Hylopezus macularius, and Hylopezus dilutus. Furthermore, Hylopezus nattereri is sister to a clade glade grouping Myrmothera, Hylopezus, and Grallaricula, representing the most divergent lineage in this complex. Our approach to assess diagnosability and define generic boundaries among these taxa integrates phylogenetic relationships with morphological and acoustic traits. Given that phenotypic and ecological differences do not warrant merging H. nattereri into any other genus, and because there is no generic name available for H. nattereri, we describe herein a new genus for this Atlantic Forest endemic lineage, Cryptopezus gen. n. We also redefine generic limits in Myrmothera and Hylopezus to have a taxonomic classification concordant with their phylogenetic relationships.