Hyphessobrycon: from the Ancient Greek υπελάσσων (hyphesson), meaning ‘of lesser stature’, and used as a prefix in this case, plus the generic name Brycon.
auca: a Mapuche (indigenous inhabitants of south-central Chile and southwestern Argentina) meaning ‘rebel’.
- Order: Characiformes
- Family: Characidae
H. auca is a species that has been identified exclusively in two ponds located within the Esteros del Iberá wetlands, which are situated in the Corrientes province of northern Argentina.
The type locality of this species is a pond within the San Juán Poriahú farm, with geographic coordinates of 27°41’53” S-57°12’17” W.
The Esteros del Iberá wetlands are the second largest wetlands in the world, following the Pantanal in Brazil. They harbor an immense diversity of plant and animal species, making them a critical ecosystem for biodiversity conservation.
H. auca was collected from two ponds situated on a sand bar formed by sediment deposited by the Paraná River during the Pleistocene era. The ponds were characterized by sandy substrates and were dominated by submerged vegetation, primarily Egeria najas, with floating Eichhornia in the marginal areas. The water in these ponds was mildly acidic, with a pH ranging from 5.6-6.8, and was soft, with a hardness of 2-5 mg CaCo3 l-1. Additionally, the water was transparent with low conductivity ranging from 11.6-20.8 µS cm-1.
Numerous fish species coexisted with H. auca in these ponds, including Acestrorhynchus pantaneiro, Aphyocharax rathbuni, various species of Characidium, Hyphessobrycon eques, Serrapinnus kriegi, Apistogramma borelli, A. commbrae, Gymnogeophagus balzanii, Laetacara dorsigera, and Phalloceros caudimaculatus. The presence of these sympatric species adds to the biodiversity of the wetlands and underscores the importance of preserving this unique ecosystem.
Maximum Standard Length
50 – 55 mm.
H. auca is a fish very similar in appearance to H. anisitsi, however can be distinguished by having a maxillary incisor with 5 tusks (compared to 3-5 tusks in H. anisitsi), the depth of the mandibular teeth is 40.7-47.6% of the mandibular length (compared to 50.0-53.3% in H. anisitsi), and there are small nodules on the dorsal, caudal and pectoral fins of males (compared to 50.0-53.3% in H. anisitsi), with no knots on these fins in male H. anisitsi).
The key difference between these two fishes is determined by their teeth and fin features. The upper incisors of H. auca always have 5 tusks, while that of H. anisitsi have 3-5 tusks on the upper incisors. In addition, the mandibular depth of H. auca was 40.7-47.6% of the mandibular length, lower than that of H. anisitsi, with the mandibular depth in H. anisitsi ranging from 50.0- 53.3%. In addition, the male H. auca has small nodules on the dorsal, caudal and pectoral fins, while H. anisitsi has no knots on these fins in males.
- Almirón, A. E., J. R. Casciotta, J. A. Bechara and F. J. Ruíz Díaz, 2004 – Revue Suisse de Zoologie 111(3): 673-682
A new species of Hyphessobrycon (Characiformes, Characidae) from the Esteros del Iberá wetlands, Argentina.