Divergence, diagnosability, and description of a new subspecies of franciscana dolphin Pontoporia blainvillei (Gervais & d’Orbigny, 1844)

Genetic data have become an important asset to enhance the delimitation of cetacean species, subspecies, and populations, considering the difficulties in obtaining representative morphological data. The franciscana, Pontoporia blainvillei (Gervais & d’Orbigny 1844), is the most threatened small cetacean in the southwestern Atlantic Ocean. Genetic studies have shown a deep genetic divergence between franciscanas from the northern and southern parts of the range; thus, it was proposed that they should be considered two Evolutionarily Significant Units (ESU). Morphological and ecological data also suggest differences across the species range. We used genetic data from samples collected throughout the species distribution (N = 399) to test hypotheses of intraspecific differentiation that could reflect the existence of subspecies within P. blainvillei. We applied the divergence and diagnosability criteria for recognition of cetacean subspecies, based on mitochondrial control region sequences. The net between-group nucleotide divergence (d_A = 0.0074) and the percent diagnosable (99%) indicate that the franciscana’s North and South ESU meet the criteria to be recognized as subspecies. Morphological and ecological evidence also support the two subspecies claim. Therefore, we propose a trinomial and provide diagnoses for the new subspecies. [ABSTRACT FROM AUTHOR]