A new species of tetra has been described from the Lower Amazon River drainage by Brazilian ichthyologists in a recent issue of the journal Neotropical Ichthyology.
Flvio Lima, Wolmar Wosiacki and Cristiane Ramosname the new tetra Hemigrammus arua after its type locality (lago So Francisco do Alto Aru).
This new tetra is distinguished from congeners in having a single, large humeral spot extending longitudinally from the fifth or sixth to the posterior margin of eighth to tenth, lateral line scales; the humeral spot possesses a pronounced upper, forwards-directed extension, assuming the shape of an inverted comma.
Hemigrammus arua is further distinguished in having reddish-orange unpaired fins in life.
According to the authors, the new tetra was collected in relatively shallow (1-1.5 meters deep) marginal areas of a large river pool that had abundant aquatic macrophytes (both emergent and non-emergent).
Gut content analysis revealed a diet of terrestrial and aquatic insect larvae, winged insects, and plant matter.
For more information, see the paper: Lima, FCT, WB Wosiacki and CS Ramos (2009) Hemigrammus arua, a new species of characid (Characiformes: Characidae) from the lower Amazon, Brazil. Neotropical Ichthyology 7, pp. 153"160.