A new platyrostrine sperm whale from the Early Miocene of the southeastern Pacific (East Pisco Basin, Peru) supports affinities with the southwestern Atlantic cetacean fauna Author Lambert, Olivier D. O. Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, 29 rue Vautier, B- 1000 Brussels (Belgium) olivier. lambert @ naturalsciences. be (corresponding author) olivier.lambert@naturalsciences.be Author Collareta, Alberto Dipartimento di Scienze della Terra, Università di Pisa, via S. Maria 53, I- 56126 Pisa (Italy) and Museo di Storia Naturale, Università di Pisa, via Roma 79, I- 56011 Calci (Italy) alberto. collareta @ unipi. it collareta@unipi.it Author Benites-Palomino, Aldo Department of Paleontology, University of Zürich, Karl-Schmid-Strasse 4, CH- 8006 Zürich (Switzerland) Departamento de Paleontología de Vertebrados, Museo de Historia Natural-Universidad Nacional Mayor de San Marcos, Avenida Arenales 1256, P- 15072 Lima 11 (Peru) aldo. benitespalomino @ uzh. ch benitespalomino@uzh.ch Author Merella, Marco Dipartimento di Scienze della Terra, Università di Pisa, via S. Maria 53, I- 56126 Pisa (Italy) and Dottorato Regionale in Scienze della Terra “ Pegaso ”, via S. Maria 53, I- 56126 Pisa (Italy) marco. merella @ phd. unipi. it merella@phd.unipi.it Author Muizon, Christian de CR 2 P (CNRS, MNHN, Sorbonne Université), Département Origines et Évolution, Muséum national d’Histoire naturelle, case postale 38, 57 rue Cuvier, F- 75231 Paris cedex 05 (France) muizon @ mnhn. fr muizon@mnhn.fr Author Bennion, Rebecca D. O. Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, 29 rue Vautier, B- 1000 Brussels (Belgium) and Evolution & Diversity Dynamics Lab, UR Geology, Université de Liège, 14 Allée du 6 Août, B- 4000 Liège (Belgium) r. bennion @ uliege. be bennion@uliege.be Author Urbina, Mario Departamento de Paleontología de Vertebrados, Museo de Historia Natural-Universidad Nacional Mayor de San Marcos, Avenida Arenales 1256, P- 15072 Lima (Peru) mariourbina 01 @ hotmail. com mariourbina01@hotmail.com Author Bianucci, Giovanni Dipartimento di Scienze della Terra, Università di Pisa, via S. Maria 53, I- 56126 Pisa (Italy) and Museo di Storia Naturale, Università di Pisa, via Roma 79, I- 56011 Calci (Italy) giovanni. bianucci @ unipi. it bianucci@unipi.it text Geodiversitas 2023 2023-11-30 45 22 659 679 https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/g2023v45a22.pdf journal article 280017 10.5252/geodiversitas2023v45a22 c02710c0-2268-4e69-9759-4c66ece777ba 1638-9395 10228752 urn:lsid:zoobank.org:pub:74B9ACDB-AEF0-40C4-97C8-D12D071A4CD4 Genus Diaphorocetus Ameghino, 1894 TYPE SPECIES . — Mesocetus poucheti Moreno, 1892 , by monotypy, known from a single specimen thought to originate from Burdigalian deposits of the Gaiman Formation, in the Chubut province , Argentina (see Paolucci et al. 2020 for the complex taxonomic history of this species). OTHER REFERRED SPECIES . — Diaphorocetus ortegai n. sp. REMARKS The referral of a new species to the genus Diaphorocetus allows for the addition of one synapomorphy to the detailed emended diagnosis provided by Paolucci et al. (2020) : dorsoventral flattening of the maxilla on the rostrum (ratio between maximum dorsoventral height of maxilla along the anterior half of the rostrum and bizygomatic width <0.1, only shared with Acrophyseter deinodon Lambert, Bianucci & Muizon, 2008 and Zygophyseter varolai Bianucci & Landini, 2006 ). Whereas most differential characters provided by Paolucci et al. (2020) apply to the new species, we propose to remove the following characters from the genus diagnosis: i) ‘rostrum [...] contributing 50% of CBL’, as the rostrum is incomplete on the types of both the included species; ii) ‘zygomatic process of squamosal with ventrally deflected apex’, as we interpret this condition as at least partly resulting from an inaccurate reconstruction of the type neurocranium of D. poucheti (see below); and iii) the differential character ‘more open jugular notch’, which appears to vary within the genus and could be easily impacted by postmortem deformation and/or reconstruction inaccuracies.