New species of Lebiasina (Ostariophysi: Characiformes: Lebiasinidae) from the upper Mazaruni River drainage, Guyana.

Lebiasina ardilai is described from the upper Mazaruni in Guyana. The new species differs from all its congeners by its color pattern consisting of: a narrow, nearly straight primary stripe, extending from posterior to humeral blotch to near the vertical through anal-fin origin, being absent or inconspicuous in females and conspicuously marked in males; the presence of four series of dark blotches at the distal border of the scales of longitudinal series 2-5; the faint secondary stripe running onto scales of second and third longitudinal row of scales; intermediate stripe absent; and the posteriorly displaced caudal blotch, not reaching the posterior tip of caudal peduncle.