Résumé
Allopatric and sympatric morphological divergence within Tilapia kottae (Perciformes, Cichlidae), endemic to the lakes Barombi Kotto and Mboandong, and affinities with Tilapias of the Cameroon Volcanic Line.
This study deals with the morphological variability within Tilapia kottae Lonnberg, 1904, a cichlid endemic of two crater lakes (Barombi Kotto and Mboandong) located in the Cameroonian volcanic highlands as well as the morphological affinities of T. kottae with others species of the genus Tilapia from the surrounding region. The Principal Component Analysis (on the morphometric and meristics characters) showed the existence of two phenotypes of T. kottae within each lake. Morphological differences concern eye diameter, length of the dorsal and anal fin base and body depth. Moreover, the populations of both lakes differ significantly in the predorsal and head lengths, and the numbers of gill rakers and of inner teeth rows on the jaws. A Cluster Analysis showed that the specimens of T. kottae shared morphological affinities mostly with the other species of Tilapia from Lakes Ejagham and Bermin, which correspond to the molecular results from the literature for the Tilapia spp. of this region. Moreover, these results illustrate the effect of the geographical isolation resulting from the fragmentation of habitats on the morphological variability of this species.