A new species of fish which gives birth to fully-formed live young has been found in northwestern Argentina.
The new species, which has been named Jenynsia tucumana, was discovered in the upper Rio Sali basin in the province of Tucuman, and has just been described by Aguilera and Mirande in a paper in the journal Zootaxa.
The new fish is a member of the family Anablepidae, which includes the well-known Four-eyed fish, Anableps anableps, and it brings the total number of species in the Jenynsia genus to around a dozen.
The new species can be told apart from the other Jenynsia species by its charactertistic row of dark markings. These range from small dots to vertical stripes and extend from the end of the pectoral to the posterior end of the hypural.
Males have a symmetrical fifth anal fin ray while females have a flat area around the vent without the urogenital swelling seen in male fish.
Aguilera and Mirande believe that the species is a sister to most other fish in the subgenus Jenynsia, apart from J. onca and possibly J. sanctaecatarinae.
For more details see the paper: Aguilera, G and Mirande, JM (2005) - A new species of Jenynsia (Cyprinodontiformes: Anablepidae)
from northwestern Argentina and its phylogenetic relationships. Zootaxa, 1096: 29"39 (2005).