Denticetopsis Ferraris, 1996

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 : 206

Genus Denticetopsis Ferraris, 1996

Denticetopsis Ferraris, 1996: 162 [type species: Denticetopsis sauli Ferraris, 1996 , by original designation].

Diagnosis. Denticetopsis can be differentiated from all other members of the Cetopsinae by the following features. The caudal-fin margin is either shallowly-forked or obliquely-truncate with the outer most rays no more than one and one-half times the length of the inner most rays (versus one and threequarters to two times that length in other genera of the Cetopsinae ). The medial most pelvic-fin ray has a membranous attachment to the body for the basal one-third to onefourth of its length (versus an attachment more typically along the basal one-half of the ray, respectively). The possession of a first pectoral-fin ray that is spinous for the basal one-half of its length further separates Denticetopsis from Cetopsis and Paracetopsis both of which lack a spinous first pectoralfin ray. Denticetopsis is further distinguished from Cetopsidium in the lack of the dorsal-spine locking mechanism that is present in the latter genus and in the having a lateral line extending either only onto the abdomen or distinctly further posteriorly onto the caudal peduncle (versus terminating above the base of the anal fin, receptively).

Remarks. The original concept of Denticetopsis by Ferraris (1996: 162) was restricted to two species, D. royeroi and D. sauli that have proved to be a subunit of a larger clade (unpublished results) that also includes two species previously assigned to Pseudocetopsis ( D. macilenta , D. praecox ) together with three species described as new in this publication ( D. epa , D. iwokrama , D. seducta ).

A single specimen of Denticetopsis in poor condition from an unspecified locality in the rio Gurupi basin, State of Maranhão, northeastern Brazil (MZUSP 42444, formerly MPEG 2660) does not fit the diagnosis of any of the species of Denticetopsis recognized in this study. In addition this sample represents the only record of Denticetopsis from the rivers of Northeastern Brazil. This specimen may very well represent another undescribed species of Denticetopsis given several differences between that individual and other examined samples of the genus, in addition to the geographic separation of rio Gurupi basin from the known ranges of the other species of Denticetopsis recognized in this study. We defer further action on the question of the identity of this specimen until such time as more extensive series of recently collected specimens of Denticetopsis from the rio Gurupi become available.