Sternum and appendicular skeleton: Morphometric differences between the species of genus Sotalia (Cetacea: Delphinidae)

Abstract

Two distinct species have been recently recognized for the genus Sotalia: S. fluviatilis, occurring in the Amazon River basin, and S. guianensis, from Honduras (15°58′N and 85°42′W) to Santa Catarina State (Florianópolis, southern Brazil-27°35′S and 48°34′W). For the first time the sternum and the appendicular skeleton of the two species of the genus Sotalia are compared. A comparative osteological work was performed with marine samples (from the States of Ceará, north-eastern and Santa Catarina, southern regions of Brazil) and riverine samples (Amazonas State) in relation to metric characters (scapula, flipper and sternum). There was a clear distinction of two species in relation to postcranial skeleton in the morphometric analysis (canonical variate analysis) presented. The flipper and the glenoid cavity of the scapula were proportionally wider in the fluvial species. The sternum, however, was smaller in this species in relation to the maximum width of the manubrium. Nevertheless, this structure still needs to be further studied. © 2012 Marine Biological Association of the United Kingdom.