Type specimens of the species of Cycloramphus Tschudi, 1838 (Anura, Cycloramphidae) in the collections of the Museu Nacional, Rio de Janeiro, Brazil.

The Museu Nacional, in Rio de Janeiro, is the oldest scientific institution in Brazil, created by a decree of the Regent Prince and future King D. Joo VI on 06 June 1818. In particular, the herpetological collection dates from the early 1870s and were studied by the first Brazilian herpetologists, namely Alpio de Miranda Ribeiro (18741934) and Adolpho Lutz (18551940). Currently, the Museu Nacional houses many type-specimens of amphibians, including species of the genus Cycloramphus Tschudi, 1838, with many problems and inconsistencies between the published data, the labels of the specimens, and the register books. In this paper, we analyse the type-specimens of Cycloramphus deposited in the Museu Nacional and Adolpho Lutz collections, described by Miranda-Ribeiro, A. Lutz, and many later herpetologists. With the purpose of contributing to the stability of nomenclature within Cycloramphus, we newly designate lectotypes for Cycloramphus eleutherodactylus var. variegata A. Lutz, 1929, Grypiscus lutzi Miranda-Ribeiro, 1935, and Iliodiscus lutzi Miranda-Ribeiro, 1929. Of the 14 nominal species treated, lectotypes for Cycloramphus eleutherodactylus var. variegata A. Lutz, 1929, Cycloramphus granulosus A. Lutz, 1929, Iliodiscus lutzi Miranda-Ribeiro, 1929, and Grypiscus lutzi Miranda-Ribeiro, 1935, are designated and figured; the holotypes of Cycloramphus eleutherodactylus var. strigillata A. Lutz, 1929 and of Cycloramphus distinctus A. Lutz, 1932, are figured; the identity of holotype and paratypes of Cycloramphus heyeri Segalla et al. 2021 is clarified. A new synonymy between Grypiscus lutzi Miranda-Ribeiro, 1935 and Cycloramphus brasiliensis (Steindachner, 1864) is proposed. Information on the type localities of all species is updated.