Melanorivulus nigromarginatus

description

Description Morphometric data appear in Table 2. Body relatively deep, sub-cylindrical anteriorly, deeper than wide, compressed posteriorly. Greatest body depth at vertical just anterior to pelvic-fin base. Dorsal and ventral profiles of trunk slightly convex in lateral view; dorsal and ventral profiles of caudal peduncle nearly straight. Head moderately wide, sub-triangular in lateral view, dorsal profile nearly straight, ventral profile convex. Snout blunt. Jaws short; teeth numerous, conical, irregularly arranged; outer teeth hypertrophied, inner teeth small and numerous. Vomerine teeth 2 - 5. Gill-rakers on first branchial arch 1 + 8. Dorsal and anal fins short, tip slightly pointed in males, rounded in females. Caudal fin rounded, slightly longer than deep. Pectoral fin rounded, posterior margin reaching vertical just anterior to pelvic-fin insertion. Pelvic fin small, longer in males, tip reaching between urogenital papilla and base of 2 nd anal-fin ray in male, reaching anus in females; pelvic-fin bases medially in close proximity. Dorsal-fin origin at vertical between base of 8 th and 9 th anal-fin rays. Dorsal-fin rays 10 - 11; anal-fin rays 13 - 15; caudal-fin rays 31 - 3

Three new species of the killifish genus Melanorivulus from the Rio Parana Basin, central Brazilian Cerrado (Cyprinodontiformes, Aplocheilidae)

diagnosis

Diagnosis Melanorivulus nigromarginatus is similar to M. egens and M. linearis, and distinguished from all other species of the M. pictus group by the presence of a black distal marginal stripe on the anal fin in males (vs. absence). Melanorivulus nigromarginatus is distinguished from M. egens and M. linearis by having melanophores strongly concentrated on the post-orbital and humeral regions, forming a stripe (vs. weakly concentrated, not forming distinct marks); presence of red dots on the anteroventral portion of flank (vs. absence); presence of red bars on most portion of caudal fin in males (vs. bars absent in M. egens and bars restricted to the dorsal portion of the caudal fin in M. linearis); and red chevron-shaped marks irregularly distributed on the flank (vs. regularly). In addition, although not useful to distinguish all specimens, M. nigromarginatus often have more scales in the longitudinal series than M. egens and M. linearis (31 - 33 vs. 29 - 31).

Three new species of the killifish genus Melanorivulus from the Rio Parana Basin, central Brazilian Cerrado (Cyprinodontiformes, Aplocheilidae)

etymology

Etymology The name nigromarginatus (black margin), from the Latin, is a reference to the presence of a black margin on the anal in males.

Three new species of the killifish genus Melanorivulus from the Rio Parana Basin, central Brazilian Cerrado (Cyprinodontiformes, Aplocheilidae)