Osteology of the African annual killifish genus Callopanchax (Teleostei: Cyprinodontiformes: Nothobranchiidae) and phylogenetic implications

Abstract

Osteological structures of Callopanchax are fi rst described and illustrated. Twenty-six characters derived from comparisons of osseous structures among some aplocheiloid fishes provided evidence supporting hypotheses of relationships among three western African genera (Callopanchax, Scriptaphyosemion and Archiaphyosemion), as proposed in recent molecular analysis. The clade comprising Callopanchax, Scriptaphyosemion and Archiaphyosemion is supported by a laterally displaced antero-proximal process of the fourth ceratobranchial. The sister group relationship between Callopanchax and Scriptaphyosemion is supported by a constriction on the posterior portion of the parasphenoid, an anterior expansion of the hyomandibula, a rectangular basihyal cartilage, an anterior pointed process on the fi rst vertebra, and a long ventrally directed hemal prezygapophysis on the preural centrum 2. Monophyly of Callopanchax is supported by a convexity on the dorsal margin of the opercle, a long interarcual cartilage, and long neural prezygapophyses on the anterior caudal vertebrae.