Phanaeus ducalis Castelnau, 1840: 79. Available name. Type specimens: Unknown to us, but certainly, the description was based on a syntypic series (rather than a holotype), since Castelnau (1840) described sexual dimorphism. Type locality: ‘ Brésil ’ (Castelnau 1840). Nomenclatural history: To our knowledge, the first author to cite P. ducalis among the synonyms of C. ensifer was Lacordaire (1856), who thought this name referred to male of this species; this synonymy was endorsed by all subsequent revisers and cataloguers (e.g., Nevinson 1892; Gillet 1911; d’Olsoufieff 1924; Pessôa 1934; Blackwelder 1944; Edmonds & Zídek 2010). No syntypes of this name were found and, therefore, a lectotype designation is not possible at the moment. For more details, see the discussion above on P. sylvanus.

Published as part of Maldaner, Maria E., Cupello, Mario, Ferreira, Daniela C. & Vaz-De-Mello, Fernando Z., 2017, Type specimens and names assigned to Coprophanaeus (Megaphanaeus) d'Olsoufieff, 1924, the largest New World dung beetles (Coleoptera: Scarabaeidae: Phanaeini), pp. 83-102 in Zootaxa 4272 (1) on page 95, DOI: 10.11646/zootaxa.4272.1.4, http://zenodo.org/record/583381