Morphological and Genetic Differentiation of Fish of the Subgenus <i>Chrysichthys chrysichthys</i> from Ivorian Rivers

Abstract

Fish of the Chrysichthys genus are subject to intense exploitation, which is threatening the available stock. The implementation of a sustainable resource management plan requires a good knowledge of the biodiversity of this genus. The aim of this study was to determine the morphological and genetic characteristics of the fish of the subgenus Chrysichthys chrysichthys in order to identify descriptors for differentiating the species of this subgenus present in Côte d’Ivoire. The biometric analysis involved forty-one morphological measurements taken from each of the 255 specimens sampled in five hydro systems. The genetic analysis of the D-loop mitochondrial DNA sequence was carried out in 34 specimens. The amplicons obtained by PCR were subjected to sequencing. Individual analysis of morphometric characters divided the subgenus into two different species: C. maurus and C. auratus. The high classification rate (>90%) of the Discriminant Factor Analysis confirmed the existence of these two species. Wilk’s Lambda test revealed thirteen discriminating descriptors. Phylogenetic analysis confirmed the existence of both species. Within the C. maurus species, fish from the river Bia are genetically different from those from other rivers. On the other hand, this population is fairly close to that of the C. auratus species, which is also divided into two different clades. Finally, molecular analysis corrected the taxonomic status of the fish.