Scientists have described a new species of Astyanax characid from the northwest of Argentina.
The new fish, which has been named Astyanax chico, has just been described by Casciotta and Almron in Germany's Zoologische Abhandlungen journal.
The tetra was collected from two tributaries of the Ro San Francisco in the northwestern part of Argentina.
Like Astyanax pynandi, ojiara, stenohalinus and troya, the males of A. chico have hooks on all of their fin rays.
These authors say that A. chico can be distinguished from these species by the presence of the following characters:
"Astyanax chico is distinguished from the remaining species of the genus by the following combination of characters: one maxillary tooth with 2 to 4 cusps; teeth of inner premaxillary row expanded distally; deep dentary bearing 7 teeth decreasing in size anteroposteriorly, males with hooks on all fins; 35-39 perforated scales in lateral series; iii-iv, 19-24 anal fin rays.
One humeral spot vertically elongated, a second lateral spot may be faint or well developed."
For more information on Astyanax chico, see the paper: Casciotta, JR and AE Almron (2004) - Astyanax chico sp. n. - a new species from the ro San Francisco basin, northwest of Argentina (Teleostei: Characiformes: Characidae). Zoologische Abhandlungen (Dresden) 54: 11-17.