A new species of Rivulus killifish has been described from the Amazon River drainage in the latest issue of Ichthyological Exploration of Freshwaters by Brazilian scientists Wilson Costa and Henrique Lazzarotto.
The new species, named Rivulus amanan, belongs to the subgenus Anablepsoides and can be distinguished from the other two species in the subgenus (R. atratus and R. ornatus) in having a unique color pattern of the caudal fin in males, consisting of an orange-red dorsal portion, black middle portion with light blue stripe, and dark red to black ventral portion.
The new species is named after the Amaa Sustainable Development Reserve, where it was collected.
The authors state that at the type locality ...he water was black with high transparency...he dissolved oxygen was always lower than 1.0 mgl-1 and the subsrate was composed by sand, silt and dead leaves. Specimens were collected only in the shallowest areas, about 0.2 m deep or shallower, with a dense layer of dead leaves.
For more information, see the paper: Costa, WJEM and H Lazzarotto (2008) Rivulus amanan, a new killifish from the Japur river drainage, Amazonas river basin, Brazil (Cyprinodontiformes: Rivulidae). Ichthyological Exploratin of Freshwater, 19, pp. 129"134.