Redescription of the bump-head sunfish Mola alexandrini (Ranzani 1839), senior synonym of Mola ramsayi (Giglioli 1883), with designation of a neotype for Mola mola (Linnaeus 1758) (Tetraodontiformes: Molidae)

The genus Mola of ocean sunfishes (family Molidae) is currently composed of three species: Mola mola (Linnaeus 1758), Mola ramsayi (Giglioli 1883), and Mola tecta Nyegaard et al. 2017. For a comprehensive revision of the genus, both literature survey and morphological investigations of Molidae were conducted. We found Mola alexandrini (Ranzani 1839) to be synonymous with M. ramsayi and we herein redescribe M. alexandrini based on the rediscovered dried holotype and 21 other fresh and preserved specimens. Mola alexandrini can be distinguished from other species of Mola by the following combination of characters in adults: head profile with bump; chin with bump; body scales rectangular; clavus rounded, supported by 14–24 (mode 17) clavus fin rays and 8–15 (12) ossicles on the rear margin. A neotype of M. mola is designated for comparison with M. alexandrini, as these two species have long been confused.