The molecular and evolutionary perspectives of a new species, S. odyssei.

ABSTRACT

Rivers and lakes of South America host 4000 fish species representing 30% of the world freshwater fish diversity. Together with a large panel of life history traits, this diversity has thus far fascinated biologists. The biogeography of the Amazonian fishes remain poorly explored, however, by contrast with the great amount of information available for South American terrestrial biotas for which several hypothesis of diversification have been developed. Yet, recent molecular studies pointed to the importance of the orogenic activity of the Andes, the marine highstand of the late Miocene, the climatic fluctuations of the Pleistocene or headwater capture events for the dynamic of the Amazonian biodiversity. The contribution of these factors in promoting biodiversity in freshwater fishes, however, is still debated. In the present contribution, the potential impact of such events during the history of the Amazon has been addressed through a combined used of biogeographic, phylogenetic and phylogeographic approaches at both regional and local scales. Present results suggest that geographic isolation as a consequence of past habitat fragmentation during major climatic and geologic changes significantly increased the diversity of Neotropical fishes. Link for the abstract can be found here.

NEW INFORMATION

When I wrote the above "FROM FRANK MAGALLANES (opinion), it was suspected that S. odyssei might have a near twin in Peru and it was being  misidentified as S. sanchezi.  Since both species appear similar. Indeed, we do have a Bolivian type 1 S. odyssei and now a Peru type 2 S. odyssei.

See photos:

Dorsal soft rays (total): 13-15; Anal fin rays 28 - 33. This species is distinguished from its congener in the Upper Amazon by the following set of characters: short supraoccipital spine 0.13-0.17% of SL (vs. typical range between 0.17-0.22% of SL in Serrasalmus but sometimes reaching 0.15 and 0.16 in S. hollandi and S. altispinnis); shallow body 0.45-0.57% of SL (vs. typical body height 0.50-0.62% in Serrasalmus); short dorsal fin, between 0.18-0.20% of SL and 13-15 branched rays (vs. 0.19-0.24% of SL in Serrasalmus); short anal fin, typical 0.32-0.37% of SL with 28-33 branched rays, but overlapping sometimes with other Serrasalmus); adipose fin located on the very posterior part of the body and distant from the dorsal fin end, typically R15 ranging between 0.19-0.22% of SL, but overlapping with other Serrasalmus with R15 ranging between 0.17-0.21% of SL); low number of scales between the lateral line and the dorsal fin, 23.5-29.5 (vs. 28.5-36.5 in other Serrasalmus); an intermediate number of prepelvic serrae 20-24. Holotype: MNHN 2005-2216. Paratypes: many at MNHN.