Ichthyologists from Argentina have described a new species of tetra from the Uruguay River drainage in Argentina, naming it Hyphessobrycon nicolasi.
The description of the tetra by Amalia Miquelarena and Hugo López is published in the most recent issue of the journal Neotropical Ichthyology.
Hyphessobrycon nicolasi is distinguished from congeners in having a well-defined, oblique and marginal black stripe on each lobe of the caudal fin.
It can be further distinguished by following combination of characters: maxilla with 13 teeth, bearing 3–10 cusps; outer premaxillary row with 2–3 small teeth, bearing 5 or 7 cusps; iv-v, 27-36 anal-fin rays; 33–36 scales on the longitudinal series; two vertically elongated dark humeral spots; rounded or fan-shaped black caudal spot; dorsal and anal fins with the first rays dappled with black; and presence of minute bony hooks on the dorsal, anal and caudal fins of the mature males.
The new species was collected from a stream with clear water and a sandy/rocky bottom.
For more information, see the paper: Miquelarena, AM and HL López (2010) Hyphessobrycon nicolasi (Teleostei: Characidae) a new species from the Uruguay River basin in the Mesopotamian Region, Argentina. Neotropical Ichthyology 8, pp. 1–6.