Redescriptions of Dussumieria acuta Valenciennes 1847 and Dussumieria albulina (Fowler 1934), two valid species of rainbow sardines (Clupeiformes: Dussumieriidae)

Abstract

Dussumieria albulina (Fowler 1934), formerly regarded as a junior synonym of Dussumieria acuta Valenciennes 1847, is shown to be a valid species and is redescribed on the basis of 29 specimens, including the holotype. Although the two species resemble each other morphologically, sharing body scales with numerous longitudinal striae posteriorly, a deep body, 26 or fewer lower gill rakers on the first gill arch, and 15 or fewer branchiostegal rays, the former is distinguished by lacking parasphenoid teeth (vs. distinct conical teeth on parasphenoid in D. acuta), higher gill raker counts (total gill rakers on first gill arch 33–41 vs. 30–38), a rather slender body (20.6–24.4% SL vs. 23.4–28.2% SL in individuals of D. acuta > 75 mm SL), and melanophores scattered on the 3rd to 9th (vs. 1st to 5th) pectoral-fin rays from the uppermost ray. Analysis of the mitochondrial cytochrome oxidase I (COI) gene in both species showed them to be separated by 12% mean p-distance. A redescription of D. acuta is also provided.