A new species of Rivulus killifish has been described from the Tapajs River drainage in central Brazil.
Killifish expert Wilson Costa named the new species Rivulus kayabi in the most recent issue of the journal Ichthyological Exploration of Freshwaters.
Rivulus kayabi is a member of the subgenus Melanorivulus and can be distinguished from other members of the subgenus in having the sides of the body with red marks arranged in a chevron-like pattern with the vertex on the ventral portion, usually with six pelvic-fin rays, 31"33 scales in the longitudinal series, a horizontal series of white spots on the dorsal part of the caudal fin in females, 13 pectoral-fin rays, 28"31 caudal-fin rays and conspicuous red bars on the sides of the body in both sexes.
Rivulus kayabi is named after an indigenous tribe that inhabited much of the region where the new species is found (the Teles Pires drainage of the Tapajs basin), and is known throughout the middle and upper sections of the Tapajs River basin.
According the author, Rivulus kayabi is found in ...shallow parts of streams and swamps, usually about 0.10"0.30 m deep, with clear water, pH about 5.7"6.0.
For more information, see the paper: Costa, WJEM (2007) Rivulus kayabi, a new killifish from the Tapajs river basin, southern Brazilian Amazon (Cyprinodontiformes: Rivulidae). Ichthyological Exploration of Freshwaters 18, pp. 345"350.