Brazilian scientists have described a new species of Moenkhausia tetra from central Brazil.
The new species, named Moenkhausia cosmops by Flvio Lima, Heraldo Britski and Francisco Machado, is described in the latest issue of the journal Aqua, International Journal of Ichthyology.
According to the authors, the new species is distinguished from other members of the genus in having ...three unique colour features in live specimens: eye with lower half bright blue and upper half bright green (with a bright golden tinge), upper lip red and most of the opercle transparent, allowing a view of the pinkish red colour of the gill filaments....
Moenkhausia cosmops can be additionally distinguished from all other members of the genus except M. sanctaefilomenae, M. oligolepis, M. diktyota, M. pyrophthalma and M. levidorsa in having a reticulated colour pattern resulting from the concentration of dark chromatophores on the free margin of the scales.
Picture kindly supplied by Leandro Sousa.
A dark, broad blotch on caudal peduncle and caudal-fin base additionally distinguishes M. cosmops from M. diktyota and M. levidorsa, and the lack of a clear area on the caudal peduncle preceding the dark broad peduncular blotch additionally distinguishes M. cosmops from M. pyrophthalma, M. oligolepis and M. sanctaefilomenae.
Moenkhausia cosmops, named after its distinctive head colour (from the Greek kosmos, meaning ornament or decoration and opos or ops, meaning face or countenance), is known only from tributaries in the Paraguai and Tapajs river drainages in central Brazil.
The occurrence of M. cosmops in both the Paraguai and Tapajs river drainages is the first documented case of a fish species shared exclusively between the two drainages and is considered by the authors to be evidence of a recent river capture between the two river systems.
For more information, see the paper: Lima, FCT, HA Britski, FA Machado (2007) A new Moenkhausia (Characiformes: Characidae) from central Brazil, with comments on the area relationship between the upper rio Tapajs and the upper rio Paraguai systems. Aqua, International Journal of Ichthyology 13: 45"54.