Cetopsidium, Vari & Ferraris Jr & de Pinna, 2005

Vari, Richard P., Ferraris Jr, Carl J. & de Pinna, Mário C. C., 2005, The Neotropical whale catfishes (Siluriformes: Cetopsidae: Cetopsinae), a revisionary study, Neotropical Ichthyology 3 (2), pp. 127-238 : 133

Genus Cetopsidium new genus

Type-species. Pseudocetopsis orientale Vari, Ferraris, & Keith, 2003 . Gender: Neuter.

Diagnosis. The combination of the presence of a dorsal fin with an ossified spinelet and the presence of pectoral- and dorsal-fin spines distinguishes the species of Cetopsidium from all other genera in the Cetopsinae . The possession of a lateral line extending to over the posterior portion of the base of the anal fin but falling short of the caudal peduncle is also unique to Cetopsidium within the Cetopsinae . The other genera within the Cetopsinae either have a shorter lateral line that is restricted to the abdominal portion of the body ( Denticetopsis royeroi and D. sauli ) or have a longer lateral line extending posteriorly at least onto the posterior portion of the caudal peduncle (all members of the Cetopsinae with the exception of Denticetopsis royeroi and D. sauli and the species of Cetopsidium ). Cetopsidium is further distinguished from Denticetopsis by having the mental barbels extending posteriorly beyond the rear margin of the opercle versus falling short of that point, respectively, and in having a deeplyforked caudal-fin margin in contrast to an emarginate or obliquely-truncate caudal-fin margin, respectively.

Etymology. The genus name, Cetopsidium , from Cetopsis , that was the first genus proposed in the Cetopsinae , and “idium” meaning diminutive, is in reference to the relatively small body sizes of the members of the genus.