Costa, 2010
Simpsonichthys harmonicus, a new seasonal killifish from the São Francisco River basin, northeastern Brazil (Cyprinodontiformes: Rivulidae)Simpsonichthys harmonicus, new species, is described from the left floodplains of the middle São Francisco River, northeastern Brazil. It is considered to be closely related to S. magnificus and S. picturatus, also endemic to the middle São Francisco River basin, by all possessing a combination of apomorphic states of morphological characters in males, including red pectoral fin, narrow black stripe on the distal margin of the unpaired fins and the ventral margin of the pectoral fin, dorsal and anal fin extremity approximately rounded, without filamentous rays. The new species is distinguished from S. magnificus and S. picturatus by the combination of pectoral fin reaching a vertical between bases of the fourth and fifth anal-fin rays in males; 21-22 caudal-fin rays; caudal fin length 31.2-33.2 % SL in males; pre-pelvic length 44.2-47.6 % SL in males; 5-7 transverse rows of dots on dorsal
fin, 6-8 on anal fin, and 6-8 on caudal fin; blue stripes on the distal portion of the dorsal fin in males; and, 13-16 bars on the flank in females.
Wilson J. E. M. Costa
Ichthyological Exploration of Freshwaters, 21 (1): 73-78, 2010.