new species:
Hyphessobrycon isiri Almirón, Casciotta & Körber, 2006

type locality:
Argentina, province of Entre Rios, arroyo Ubajay at a place called Manantiales within estancia Los Monigotes (31°48,94’ S – 58°12,41’ W); holotype: MACN-Ict 8907 (44,6 mm SL, female), paratypes AI 193

further localities in Argentina (paratypes):
– Corrientes, río Uruguay basin, arroyo Mota, 30°28’55”S – 58°15’44”W
– Entre Rios, río Uruguay basin, arroyo Mármol, 32°03’44”S – 58°15’44”W

published in:
Almirón, A.E., J.E. Casciotta & S. Koerber (2006):
A new Hyphessobrycon (Characiformes, Characidae) from the río Uruguay basin, Argentina.
Revue Suisse de Zoologie 113 (4): 889-896

abstract (from publication):
Hyphessobrycon isiri sp. n., is described from the río Uruguay basin. Hyphessobrycon isiri sp. n. differs from the remaining species of the genus by the presence of teeth of the inner series of the premaxilla with 5 to 11 cusps, one maxillary tooth with 7 cusps; 16 to 22 branched anal-fin rays; one humeral spot vertically elongated, and a midlateral stripe ending in a conspicuous caudal spot.

habitat notes (from publication):

The arroyo Ubajay in its lower portion forms the limit of ‘Parque Nacional El Palmar’ towards the south and ‘Los Monigotes’ farm towards the north. The upper portion is completely located on farm grounds. Its two springs are found in grassland hills typical for the area used for cattle. At the junction of the two brooks a small farm dam 2 meters deep probably allowed the permanence of some species which apparently are not present permanently in the remaining length of the brooks (which are only 20 cm deep in average). This pond, located some 3 km from the Río Uruguay at 31°48,94’ S, 58° 12,41’ W, is the type locality of the new species. The bottom is covered with gravel and rocks in the areas with current and with sand and mud in the stretches devoid of, or with low current. The vegetation is reduced to grasses hanging from the banks and aquatic species as Nymphoides indica, Ludwigia sp. and Bacopa sp. The poind was almost completely exposed to sunlight, except for small shadow provided by a few marginal bushes. At the time of collecting the water was turbid after rains during the previous days.