Phycocharax rasbora male (a) and female (b).
This lovely little characin represents both a new genus and species. It was discovered recently in a tributary of Rio Teles Pires, Tapajos basin, Mato Grosso, Brazil.
It has been named Phycocharax rasbora, the genus name deriving from the Greek phykos, meaning “algae”, in allusion to its feeding habit, plus charax, meaning “pointed stake” or “palisade of pointed sticks”.
Males were noticeably more coloured than females, and the upper portion of eye was red to shiny red, compared to pale red in females, along with differences in the shape of the anal fin. The largest specimens examined were 3.4cm (male) and 3.1cm (female).
It was collected primarily in dammed portions of the Rio Braco Norte. The authors say: “Contrasting from other tributaries of the Rio Tapajos basin, which are primarily clearwater rivers, the Braco Norte is a blackwater tributary of the Rio Teles Pires. In the site of occurrence of P. rasbora was a small hydroelectric dam and apparently the reservoir condition promoted the proliferation of algae. As consequence of the damming, the species thrived and can be considered as highly abundant at the dammed portion of the rio Braco Norte".